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*A history of Mars*

* *

by Greg M. Orme.

Mars has a mysterious history. Many of the facts we know seem to be
conflicting, for example it seems to have had a history of water flows
which seems to contradict its current cold state. Valles Marineris is
also hard to explain, a large rift valley with apparently no plates,
which are needed on Earth to create them. There are many water flows
from craters but there should be no water in those areas. Craters are
unevenly distributed on Mars, covering only half the planet to a large
degree and this coincides with a drop in height called the dichotomy
boundary.

Here an attempted explanation is made based on large scale events, which
may have driven most of the Martian changes and created the paradoxes we
see today. It is a forced sequence of events so if the basic premises
are accurate then it is quite likely something like this occurred,
though perhaps in a different order.

The 4 largest outside influences we know about Mars are probably the
last four big impact craters, Utopia, Isidis, Argyre, and Hellas. Since
much of the confusion about Mars arises from the fact that we don’t
perceive its evolution to be understandable compared to our own, this
theory attempts to explain it by outside events driving the changes.

If a planet was perfectly round a pole might tend to wander over time.
Usually planets are a spheroid, which means they are like a slightly
flattened ball, and the wider parts tend to be at the equator. This is
because the extra weight tends to go to the equator where it wields more
force because it spins faster there.

The converse of this is that an absence of mass such as an impact crater
or large valley like Valles Marineris would tend to go toward a pole
since they become the equivalent of the flattened part of a spheroid. We
also know that on Mars large impacts typically form a Mons or mountain
on the other side of the planet, though sometimes not exactly opposite
the crater. Logically this Mons would take a long time to form and we
know that the Tharsis Montes for example probably continued to grow and
restart through much of Martian history.

So at first with an impact there is an immediate tendency for the crater
to move to the pole, and then as the Mons grows on the other side this
weight fights to move to the equator and eventually may overcome the
lack of mass in the crater. Also the crater may partially fill up over
time as Utopia Basin appears to have[1] <#_ftn1>. It may then be that at
first the crater moves to the pole and then after time moves toward the
equator as the Mons grows. By having 4 impact craters and their
associated Mons doing this it can make the resultant climate on Mars
vary wildly, and make it much harder to decipher.

Also as a crater moves toward a pole its gravitational influence
diminishes, so it will likely stop near but not exactly on the centre of
the pole. It may also fill partially with ice and this addition of mass
in it can further stop it moving closer to the pole. If the climate then
changes for example with the heat added to the atmosphere by the
volcanism of the Mons then this amount of ice can further fluctuate
moving the pole as well. This would be because the warmer climate might
move ice from the pole to the equatorial regions, and perhaps sublimate
CO2 from the poles.   

While a Mons can be initiated by an impact it can also be altered or
even restarted by additional impacts if the shock waves are strong
enough. For example in here I will show that Isidis may have weakened
the Tharsis area, which was further affected by an oblique impact from
Argyre, and then from Hellas. This would have contributed to these
volcanoes restarting many times until they reached their enormous size. 

Generally it is believed that a large impact like Hellas would naturally
make a large Mons on the other side of Mars, but the record from large
impacts is not so clear. Utopia Basin and Isidis Basin have no large
Mons opposite them, Argyre has Elysium Mons, and Hellas is hard to line
up with the Tharsis Montes and Olympus Mons though it lines up well with
Alba Patera. There is however enough of a correlation to think they are
related.

The main theory is that when the impact occurs the core acts like a lens
focussing the shock waves onto the crust on the other side of the
planet, either exactly opposite or somewhat offset if the impact is
oblique. This theory has several problems however. One is that a
spherical core is not really the right shape to focus shock waves like
this; such a shape should tend to defocus the waves. Also we don’t know
the relative densities of the materials involved so we can’t say for
sure what angle of deflections would be made by such a lens. As Mars
became progressively deformed impacts happened from different elevations
and so it would seem unlikely all of these would just happen to give
such a precise focus to create a Mons.

The effect of shaping sound waves by a lens is well known, dolphins use
it for example to direct their sonar.  

A more likely explanation might be that as the shock wave spreads there
is a small cone of the wave that goes directly through the centre of the
core and other layers, and because over this area the surface of the
core is relatively flat then this cone of the shock wave would tend to
be not defocused. Outside of this cone the shock waves would tend to be
defocused and perhaps distributed evenly over the opposite hemisphere to
the impact crater.

People who need glasses can see a similar process. Squinting can improve
eyesight because the light goes through a narrow aperture, which is
similar to shock waves going through the centre of the core. The narrow
beam that gets through the core without being defocused might by itself
create only a very narrow circle of damage on the surface crating one
small volcano, compared to a large area of devastation.

Other parts of the shock wave may even be reflected back so we may get
bands of general volcanism as the force is distributed over a large
area. For example the core and other layers should have an angle of
reflection so that waves hitting at a shallow angle tend to bounce off
it and waves at a steeper angle tend to refract into the core. Large
enough impacts may even affect the magnetic field in the core and
perhaps and stop the magnetic dynamo[2] <#_ftn2>.

This general spreading of the shock waves could have induced a general
increase in volcanism over the whole planet and perhaps in certain
bands, so these may explain larger volcanic flows[3] <#_ftn3> [4]
<#_ftn4>.  As we will see later the two main areas of Noachian
craters[5] <#_ftn5> may have been preserved by their having been under
poles and thus have resisted volcanic resurfacing.

Some of the Martian names are shown on 2 maps[6] <#_ftn6> [7] <#_ftn7>.
Also the polar wandering path of Sprenke et al[8] <#_ftn8> is referred
to, these are adjusted to give a polar path more in line with impact
craters and known deposits of ice found, which may correspond to old
poles[9] <#_ftn9>. It is not possible to be exact with the positions of
poles so long ago; also they may not have been circular. The current
poles for example are not, which may be caused by the pole still moving.

*The Utopia Impact*

While previous impacts may have shaped Mars[10] <#_ftn10> [11] <#_ftn11>
I begin here with the Utopia impact basin[12] <#_ftn12> [13] <#_ftn13>.
Thomson and Head conclude this is an impact basin and also that it is
very ancient, likely much older than Isidis, Argyre and Hellas since it
is much shallower[14] <#_ftn14>. Isidis basin is on the edge of Utopia
Basin, implying from its shape that it was formed later. There has long
been controversy over whether this is an impact basin or an ancient sea.
Thomson and Head argue the model of an impact basin as opposed to an
ancient sea or ice sheet but the pole in the basin would perhaps make
both indicators be seen together[15] <#_ftn15>. This area could have
been a Northern ocean especially when the Utopia impact basin was still
warm from the heat of the impact. I refer to the centre of Utopia Basin
as *North Pole 1* and subsequent poles are in numerical order. The
current pole is *Pole 5*.

Interestingly similar lacustrine and volcanic arguments are made[16]
<#_ftn16> in Valles Marineris which we will see later may have formed
from the Isidis and Argyre impacts. If the pole had moved to the area of
Valles Marineris in combination with the volcanic activity from the
impacts tuyas may have been formed as well.

Smith et al[17] <#_ftn17> believe Valles Marineris may have formed after
Argyre and Hellas, but this may also indicate those impacts helped to
increase the rifting after it began with the Isidis impact. Valles
Marineris is a large negative gravity anomaly[18] <#_ftn18> and so
should tend to move to a pole as well. With the Isidis impact it was
already near a pole, so this tendency was already realised.

As time progresses it moves further from the pole and as we will see
towards the equator where it largely remained through further polar
wandering. This implies it did not get much larger, or that if it did
the negative gravity was compensated by the increased mass nearby of
Tharsis Montes, Olympus Mons and the area around Solis Planum. If its
rifting had have happened separate from an impact then we should expect
to see the advance of the poles towards these impacts to be reversed at
some stage when Valles Marineris was formed. This implies then that
either it was never a significant negative gravity anomaly which seems
unlikely or it formed in circumstances where its lack of mass were
already compensated for and this did not change with a widening
unrelated to the forming of further Mons from impacts. It is likely then
that Valles Marineris was formed around the same time as the Tharsis
Montes.

Sprenke et al[19] <#_ftn19> show no such change in the polar path
heading back towards Valles Marineris or even seemingly being affected
by it. Smith et al[20] <#_ftn20> also show how the current gravity of
the Valles Marineris area is dominated by Tharsis Montes and Olympus
Mons, and also by the area around Solis Planum, which also indicates the
Utopia and Isidis impacts could have made that area heavier, slowly
negating the negative mass of the Utopia and Isidis impact basins and
allowing the pole to move on and this area to move towards its equator
at the time. This area is shown in *Figure 1*[21]* <#_ftn21>*.

Isidis Basin also has rootless cones, which according to Martel[22]
<#_ftn22> may be formed by lava flows over water or ice. This would also
be consistent with a pole here, and avoids the need to assume large
amounts of ice all over Mars. Moore et al[23] <#_ftn23> believe fluvial
erosion occurred in the Noachian to Hesperian.

The centre of this basin is 45 degrees North 248 degrees west, so
directly opposite this is 45 degrees south and 68 degrees west. This is
shown as *A* in *Figure 2*[24] <#_ftn24>.

Interestingly this area has no Mons at all, though normally there should
be one or more from the shock waves. The ground is raised around Solis
Planum however and all the way to the Tharsis Montes. It may be then
that the rifts around Solis and Syria Planum may have been partially
formed from the Utopia Impact, where the whole area was raised rather
than a narrow Mons.

The Argyre impact basin is very close to *South Pole 1*, and it may be
that this hit the Mons opposite Utopia Basin, and removed all traces of
it. The other possibility is that the Mons was in the area of Syria
Planum and was either damaged in the Argyre impact or had eroded to a
smaller size. This might account for the generally raised area around
Solis and Syria Planum.  

*The Isidis Impact*

The next oldest impact may have been Isidis[25] <#_ftn25>. If it has
happened before the Utopia impact then likely it would show the effects
and perhaps have been buried. It seems apparent that water flowed from
the Isidis Basin into the Utopia Basin[26] <#_ftn26> [27] <#_ftn27>.
Argyre also appears to be much younger.

When the impact occurred it would have moved closer to the pole, and the
pole opposite would have also moved. The centre of the Isidis Basin is
12.7N 272.6W[28] <#_ftn28>, giving the other pole as near 12.7S 92.6W,
shown as *B* in *Figure 2*[29]* <#_ftn29>*.  This would place it in
Sinai Planum. So from one impact to another the pole may have moved from
45S 68W from the Utopia impact to 12.7S 92.6W. We cannot say where
exactly *South* *Pole 2* was, though it is likely near a line between
*A* and *B*.

Isidis is also the landing place for Beagle 2[30] <#_ftn30> [31]
<#_ftn31> [32] <#_ftn32> [33] <#_ftn33>. Being very flat it is also more
likely to be older than Argyre and Hellas. It also has signs of fluvial
activity[34] <#_ftn34>, which could be from when it was at or near a
pole. Toon[35] <#_ftn35> says that large craters and river valleys
appear to be the same age. This can be from impacts melting water, but
also from impact craters moving to a pole which attracts ice and perhaps
water if the craters retain some heat.

The elevated areas between Solis Planum, Icaria Planum, and Aonia then
may have been caused by these two impacts. It also turns out that even
though water signs were not picked up here by ODYSSEY[36] <#_ftn36> [37]
<#_ftn37> the area is thought to contain ancient water deposits[38]
<#_ftn38> [39] <#_ftn39> [40] <#_ftn40>.

Barlow et al suggest the area has contained ice since the Hesperian[41]
<#_ftn41>, which fits in well with an ancient pole having been there.
Interestingly they suggest the water table may have tilted here with the
formation of Tharsis[42] <#_ftn42>, which agrees with the time lines
suggested in this paper. Instead of or in addition to the water
accumulating here from Tharsis it could have accumulated from a pole
forming here.

This agrees well with the proposed poles by Sprenke et al, who begin
their polar wander at 45S 90W and then move to approximately 30S.  It is
more difficult to see signs of the opposing *North Pole 2* around Utopia
Basin though ice signs are seen[43] <#_ftn43>.

Not only does the area around *South Pole 2* in Syria Planum not show
ice signs from ODYSSEY but they show the opposite, of being some of the
driest parts of Mars. This conflicts with what is seen in Solis Planum,
where fluidised ejecta from craters is known[44] <#_ftn44>. It may be
then that there was ice here at one stage but events drove the water
out. Since this area is opposite the Utopia and Isidis impact basins it
implies that heating from those impacts may have removed the ice. Some
ice may still be there[45] <#_ftn45>.

After the Utopia impact this area would have become saturated with ice
and perhaps water as it became a pole, and we know from the ejecta ice
was there.

The pole may have extended into Solis and Sinai Planum in the middle of
the raised ridges and rifts, though only the ones to the south may have
been there then. Since this is opposite the Isidis impact and roughly
follows the path of polar wandering by Sprenke and Baker it seems a
reasonable possibility.

While the impact of Isidis may explain the lack of water signs opposite
Utopia Basin it cannot explain the lack of water signs opposite Isidis
itself. An additional event may have happened to make the further rifts
around this pole, I call *Pole 2* (*Pole 1* would have been formed by
the Utopia impact). Valles Marineris may have been formed from this
further event.

Syria Planum is said by Webb[46] <#_ftn46> to be surrounded by a raised
annulus as well. Stresses then are likely to have created the rifts such
as Valles Marineris and allowed these Planum to subside. Instead however
of Tharsis forming this strain this may have been done by the combined
impacts of Utopia and Isidis, and that forming a pole of ice here
restricted the volcanic effects to their perimeter. Scott[47] <#_ftn47>
argues that Syria, Sinai, and Solis Plana were formed with a mantle
plume, which is consistent with the idea of heat from the Isidis impact.
The subsidence may have been partially formed by the weight of the polar
ice.  Also Scott[48] <#_ftn48> says this upwelling may have been enough
to form Valles Marineris[49] <#_ftn49>. This area may also have escaped
resurfacing from Tharsis because of this higher elevation according to
Smith[50] <#_ftn50>.

Hartmann[51] <#_ftn51> says Solis Planum also has well preserved
craters, with larger craters more preserved. This may be because of the
pole being there for a long time, having buried craters in ice.

Arsia Mons[52] <#_ftn52> [53] <#_ftn53>is roughly at 12S 120W, the same
latitude as *South Pole 2*. It is also the largest of the 3 Tharsis
Montes as well as being closest to the opposite of the Isidis Impact.
Head says evidence of glaciation[54] <#_ftn54> [55] <#_ftn55> has been
found also on Pavonis Mons and Ascraeus Mons, which is suggested to be
from the late Hesperian. This may also have been from the time the pole
was nearby. Few signs of water are seen, which would be consistent with
polar ice. Head and Marchant[56] <#_ftn56> also say that Arsia Mons had
volcanic outflows into the Hesperian, which is consistent with later
impacts restarting the flows. Sprenke et al[57] <#_ftn57> say that the
Tharsis Montes may have been formed after the Martian global magnetic
field ceased, which might imply the Hellas and Isidis impacts had
affected this field. It may also mean the volcanoes were reactivated
later in subsequent impacts. Vast amounts of ice may be there even
today[58] <#_ftn58>.

*Argyre Impact*

Next the Argyre impact[59] <#_ftn59> may have occurred. Assuming *South
Pole 2* was at Sinai Planum it would have been likely that this was an
oblique impact. Argyre Planitia is shallower from the West to the North
though it is deepest to the North West. Argyre is centred on
approximately 50S 42W, and the Sinai Planum *South Pole 2* may have been
at 12.7S 92.6W. Sprenke’s[60] <#_ftn60> pole position would be 30S 90W
so both give an oblique impact assuming the meteor came from within the
ecliptic plane of the asteroid belt.

Looking at the higher elevations North West of Argyre Basin it seems
these reach from Argyre all the way up to Valles Marineris and west to
the northern edge of Icaria Planum, seen in *Figure 3*[61] <#_ftn61>.
Illustrated in *Figure 4*[62] <#_ftn62> if you draw a line though
Olympus Mons *A* and Pavonis Mons *B* then Arsia Mons and Ascraeus Mons
*C* would be at close to right angles to this line as would the annulus
*D* to the North West of Bosporos Planum. This also points at the centre
of the Argyre Basin. The annulus west of Syria Planum and Solis Planum
*E *would be approximately the same angle as Valles Marineris shown here
as two lines *F* and *G*.

It may be then that while these features were partially formed by the
Utopia and Isidis impacts the glancing blow of Argyre sent a shock wave
in a shallow angle and created them. This would be the same mechanism as
an impact on the other side of a planet except in this case the main
shock wave comes from the side. The shock wave is always strongest in
the path of the impact because the sound waves are most compressed along
that line by the speed of the meteor and hence the frequency is most
raised. So the strongest force in an oblique impact should be along the
line of the impact trajectory.

This triangular shape can be approximated by shining a torch onto a
circular bowl at an oblique angle, though the sides are more rounded. A
shock wave would generally be cone shaped rather than cylindrical like a
torch beam but the diffusion is unlikely to be great over this distance.
As the beam goes through the pole at a shallow angle it would come out
roughly in this triangular shape. The edges of the shock wave would tend
to shear the ground creating an approximately triangular or egg shaped
annulus and rifts. Rifting and faulting would tend to be in straighter
lines making the shape more triangular.

The same thing may have created the triangular shape of Olympus Mons and
the three Tharsis Montes, perhaps from a reflection from a subsurface
layer. If a shock wave hits a denser layer below at an angle it may
glance off like a light beam reflecting off a pane of glass at a shallow
angle. The shape of this shock wave can be seen by shining a torch on a
globe (representing the denser layer) at an oblique angle.

The shape is approximately the same, and faults would tend to be in
straight lines to create the Tharsis Montes in a straight line. Here[63]
<#_ftn63> Tharsis Montes and Olympus Mons are overlaid on this annulus
shape together with Valles Marineris to show the similarity of the two
shapes.

Another possibility is that the shock wave pointed directly at Tharsis
and Olympus Mons, and a reflection made Valles Marineris and the rises.
A geological layer would not reflect perfectly because of its rougher
surface so some parts of the shock wave would go through and another
part would reflect even when the angle of reflection favoured one or the
other. A good analogy would be for light reflecting off frosted or
roughened glass where some parts would reflect and others refract.

In this case then Valles Marineris would have been stressed but not
rifted by the Isidis impact and upwelling and then sheared into a rift
valley from the Argyre shock wave.

There are no signs of volcanic activity in any other direction from
Argyre, which also implies a glancing impact. On the other side of Mars
Elysium Mons would have been also formed from the impact. There are
three Mons[64] <#_ftn64> opposite Argyre, Hecates Tholus, Elysium Mons,
and Albor Tholus. This also connects the shape of Tharsis Montes plus
Olympus Mons to the three opposite Argyre. The triangular shape of these
three Mons may have occurred from a refraction of the somewhat
triangular shock wave.

Hiesinger has out six scenarios for the evolution of the Argyre basin.
Surious Valles has a delta shape, which may have been from water as
*South Pole 2* melted. There is also evidence for a proglacial lake.
Water signs are found there but too high for water to come in from the
northern lowlands. A polar meltback[65] <#_ftn65> was proposed by Parker
et al[66] <#_ftn66> though not in the *South Pole 2* position. 

Elysium Mons is close to the Isidis basin which would have been the
opposite *North* *Pole 2* at the time.

Such an oblique impact hitting the polar ice may have expelled large
amounts of water and ice from Mars; indeed it is hard to imagine an
event more likely to do so. Also if at this stage Mars had substantial
amounts of frozen gases such as CO2 at the pole this could also have
been ejected leaving the atmosphere much thinner. Much material from the
crater may have also been removed from mars which could have
subsequently made its negative mass more influential relative to the
coming shift to *Pole 3*. Some ejecta may have added to the annulus to
the west of Bosporos Planum *D* and even to the raised area further
North West.

The subsequent heat would have melted much of the pole and raised the
overall Martian temperature. If gases were frozen this would have raised
the air pressure and allowed more liquid water, also floods from the ice
melting were likely. Signs of these are probably shown in Valles
Marineris which has an elevation sufficient to carry water into
Margaritifer Terra and Chryse Planitia[67] <#_ftn67> which are also
shown in *Figure 4*. In Lunae Planum there is also evidence of large
scale flooding, also on Xanthe Terra, but little south of Solis
Planum[68] <#_ftn68> and perhaps some into Argyre Basin which would be
too hot at this time for water to channel into it. The water may also
have gone North West[69] <#_ftn69> if Tharsis was not large at this time.

*South Pole 2* would try to reform polar ice and water but the heat
would drive it away. This then may explain why this area had evidence of
water from ejecta in craters but this seems to have disappeared
according to Odyssey[70] <#_ftn70>, also shown in *Figure 5*[71]
<#_ftn71>. As shown in *Figure 6*[72] <#_ftn72> one red section appears
to radiate out of Argyre from the west *A* to the north *B*, and the
second one sits in Solis Planum *C* where *South Pole 2* may have been.
This indicates the Argyre impact may have dried out these areas, which
is why they showed fluidised ejecta in the past but now show little ice.
It may even have dried out east of Ascraeus Mons.

Later water would drain from the Argyre Basin as it cooled and water ran
into it from *South Pole 2*. The raised annulus west of Bosporos Planum
may also have prevented water going to the basin, as well as south to
Aonia.

Thaumasia[73] <#_ftn73> shows deformational features radiating from the
Argyre Basin which may show the impact had influence this far. While
also radial to Tharsis here they may be more related to Argyre.

The large negative mass of the Argyre basin would have begun a pole
shift. Also as the impact helped to grow Tharsis Montes and Olympus Mons
they would have tended to move to an equator which would have also
helped to shift the pole. As we will see according to the polar wander
path of Sprenke and Baker Tharsis and Olympus Mons move directly closer
to an equator westward, which in turn moves the pole eastward.

Sprenke et al show a movement of the pole to approximately 0S and 30W
and then to 330W. This would take the pole to North of Argyre Basin into
Margaritifer Terra and then east to Meridiani Planum. Since it is
unlikely the pole stopped in Margaritifer Sinus this is not given the
name *South Pole 3*, that is for when the effects of the Argyre impact
stabilise a new pole. So the pole wanders from Sinai Planum *A* through
Margaritifer Sinus *B* to Meridiani Terra *C* heading eastward, shown in
*Figure 7*[74] <#_ftn74>.

According to Grant[75] <#_ftn75> Margaritifer Sinus contains high valley
densities, which would be consistent with the pole moving and
subsequently ice melting. Also the area was resurfaced several times[76]
<#_ftn76>, perhaps from the subsequent volcanism from the Argyre impact.
While Grant[77] <#_ftn77> believes some precipitation occurred most
would have been from ground water, which is consistent to a water table
associated with a forming pole. This discharge[78] <#_ftn78> lasted a
long time according to Grant[79] <#_ftn79>. The Parana Valles[80]
<#_ftn80> drainage system is particularly extensive.

Hynek et al[81] <#_ftn81> believe this time of fluvial resurfacing
lasted several hundred million years. A combination of rainfall and
sapping[82] <#_ftn82> appear likely, which may have formed a lake for a
time[83] <#_ftn83>. A moving pole then may link the two main theories of
precipitation and sapping to explain the valley networks[84] <#_ftn84>,
and that according to Nelson a large build up of ice which periodically
melted. Philips et al[85] <#_ftn85> examined Margaritifer Sinus and
concluded much of the Tharsis bulge was already in place before the
drainage channels were formed, which is consistent with the general rise
in elevation in the area of Tharsis and Sinai Planum from the Isidis
impact. Further growth of Tharsis could happen later, though at the late
Noachian it was large enough to direct the channels northward. Large
amounts of material from this area were removed along these channels
probably from water erosion as the pole melted, and moved into
Margaritifer Sinus.

Valles Marineris[86] <#_ftn86> [87] <#_ftn87> [88] <#_ftn88>  is then
likely to have formed from the stresses of the Isidis and then the
Argyre impacts, making its origin harder to see[89] <#_ftn89> [90]
<#_ftn90>. By this time water and ice would have accumulated in it as
the pole melted and moved, which may explain the paleolakes[91]
<#_ftn91>. Carr[92] <#_ftn92> suggested that ground water flowed into
Valles Marineris and then[93] <#_ftn93> into Chryse Planitia, forming
lakes. Rossi et al[94] <#_ftn94> believe there is good evidence of ice
and glaciers which would be consistent with a polar area.

Lunae Planum, also shown in *Figure 7*[95] <#_ftn95> would also have
received water from the moving and melting pole. Greeley and Kuzmin[96]
<#_ftn96> show how Shalbatana Valles originates in the chaos on Lunae
Planum. Interestingly it comes from a probable impact basin that formed
a catastrophic outflow. This impact may have occurred before or at the
same time as Argyre, though its shape (not mentioned by the authors)
would likely be elliptical if from the time of *South Pole 2*. While it
is suggested the impact breached an aquifer this would be unusual for
Mars. It does link the area with large amounts of water and probably ice
triggered from an impact, something not seen elsewhere. A pole here
would supply the water, and once it carved a channel keep it going with
more water. A nearby elliptical formation, Orcus Patera[97] <#_ftn97>
may also have come from an impact, its shape implying a pole was near here.

Xanthe Terra also shows evidence of water flows. Nelson and Greeley[98]
<#_ftn98> discuss 3 major fluvial events here. The first is a broad
sheetwash from the Valles Marineris area perhaps coinciding with the
Argyre impact. Then there was more extensive water forming Shalbatana,
Ravi Simud, Tiu, and Areas Valles which might coincide with the pole
moving to Margaritifer Sinus. Most of this water came from chaos
areas[99] <#_ftn99> which would link to the Argyre impact. Subsequent
flooding would be as the pole continued to move, and when further enough
away the water would cease.

In the new Odyssey results of subsurface ice[100] <#_ftn100> there is a
large deposit on the equator in Babaea Terra shown in *Figure 8*[101]
<#_ftn101> and centred at 330 degrees west. Another one can be seen on
the left edge of the map just below the equator shown in *Figure 9*[102]
<#_ftn102>. This would correspond to the opposite pole. According to
Sprenke et al the pole moves in a curve through this ice rich area to 0S
330W, almost the centre of the ice rich area. I call this area *South*
*Pole 3*. Having icy areas opposite each other like this makes it likely
they were poles.

This can be explained from the effects of the Argyre impact. As the
Tharsis and Olympus Montes grow they accumulate more mass which seeks to
go to the equator. The movement of the pole to this area allows these to
get much closer to the equator. Tharsis and Olympus Montes are today on
the equator at around 120W and the pole would have moved to 330W. This
adds to 150 degrees so the Montes would have nearly reached the equator,
which indicates their weight was dominating at this stage. The pole has
assumed a position between the Argyre and Isidis impact basins as each
would have had a tendency to be near the pole.  

This would tend to be a stable configuration. The Montes have grown
enough to get near the equator so little more can move them closer.
Elysium Mons has probably also formed to some degree which reduces some
of the negative mass tendency of the Argyre Basin. It is at 210W so
there is more than 120 degrees between there and the pole. *Pole 3* then
would be balanced with Olympus Mons and Tharsis Montes tending to go to
the equator and Elysium Mons almost opposite them also near the equator,
and Isidis, Utopia, and Argyre basins around *South* *Pole 3*.

This also implies the growth of these Montes is strongly linked to the
Argyre impact as the pole moved from near the Argyre Basin to mid way
between it and the Isidis basin. If the Argyre impact had not happened
then, its happening now would scarcely move the pole. It would be
unlikely an impact causing the Argyre basin happened then just at a time
where it wouldn’t move the pole. Also that Elysium Mons has moved
towards an equator which it wouldn’t have done if it hadn’t formed yet.
Logically then the Utopia, Isidis, and Argyre impacts had to happen in
this order, forming their respective Mons in the order described for
this polar wander path suggested by Sprenke.

Interestingly *South Pole 3* coincides with an area of heavy
cratering[103] <#_ftn103> and the second cratered area corresponds well
with the opposite *North Pole 3* in *Figure 9*[104] <#_ftn104>. One
likely explanation is that the polar ice protected the craters[105]
<#_ftn105> from erosion, and when they were exhumed from the ice they
remained in more pristine condition. *Pole 3* probably lasted a long
time to give this crater disparity. It also implies at this time that
the surface was being altered severely and other craters were being
buried or obliterated by lava flows.

This may be because of the shock wave effect of these impacts which may
have sent shock waves over large parts of the surface initiating
volcanism. This would explain how volcanoes have apparently restarted in
Martian history and the surface being relatively young in parts. *Pole
3* likely remained here through this resurfacing. Since these crater
areas are linked into what is termed the Noachian surface it may be that
the time after the Argyre impact may be regarded as the Hesperian,
obliterating much of the Noachian terrain except for these parts
protected with polar ice. Some other areas with Noachian craters are
also found around Margaritifer Sinus, implying the pole may have slowly
moved and protected other areas for a time in its path.

In moving from *Pole 2* to *Pole 3*, the polar ice closely follows and
may have formed the dichotomy boundary. The main boundary is seen
between 180 degrees west and 90 degrees west, which is 270 degrees or ¾
of a total possible boundary. The rest is taken up by the land mass of
Tharsis Montes, Syria Planum, etc. *South Pole 2* moved from 12.7S 92.6W
eastward to approximately 0S 330W, which is approximately 122 degrees of
longitudinal movement or approximately 1/3 of the total great circle.
The opposite pole travels from 12.7N 272.6W to 0S 150W, which is where
the dichotomy boundary ends against Olympus Mons, for a movement of 122
degrees. This makes then 244 degrees of movement over a dichotomy
boundary of 270 degrees as a polar path. The rest can be explained by
the width of *South Pole 3* at 330W, which makes it appear to extend
further east. So of the total visible dichotomy boundary virtually all
of it is on the same line as the movement of *Pole 2* to *Pole 3* which
is unlikely to be a coincidence.

The pole then moves through Margaritifer Sinus and from here there is a
green elevation path. This trail begins at east south east of *Pole 2
*so the pole may have initially moved towards the Argyre crater, which
is logical as its negative mass should move towards the pole. This
implies the pole may have moved along this green area and lowered the
terrain there.

The pole was probably moving on a slope, which may make the path easier
to see than from *South Pole 3* to *South Pole 4* where the ground was
not sloping. We already know the planet tends to slope towards the
current North Pole, *North Pole 5*, and that this polar path is lower
than the terrain south of it, and higher than the terrain north of it.
This then implies the moving pole may have flattened part of a slope
going into Acidalia Planitia and for the opposite Pole Elysium Planitia.

A pole moving on a slope like this would tend to have a runoff of water
heading North through the journey. Depending on the temperatures and the
air pressure at the time ice may have sublimated directly into water
vapour and CO2[106] <#_ftn106> may also have been a primary erosional
force. On the sloping ground water, mud and perhaps CO2 ice would tend
to move like glaciers, with material in the ice moved north through
avalanches and liquid CO2 as described by Hoffman. Dust that formed on
the pole through dust storms then would be moved north and perhaps
create a very smooth surface in Acidalia Planitia, Utopia Basin and
Elysium Planitia.

As the pole moved new ice would tend to form on the ground ahead and
melt on the ground behind it as the temperatures changed. The ice in
front would tend to freeze into the soil and create a similar situation
to the current *Pole 5* where approximately half or more of the soil is
ice. When this eventually melted or sublimated the soil in the ice
should have moved down the slope and spread out. If there was a high
enough air pressure this should have created a seasonal water flow into
Acidalia Planitia and created the smooth surface. CO2 might give the
same movement at lower temperatures.

It is likely the temperatures of Mars were dropping from the Argyre
impact, there are visible water channels in Lunae Planum, Xanthe Terra,
and Margaritifer Sinus, but these are no longer seen as the pole moves
eastwards. The edges of the green elevation may indicate the edges of
the permanent ice cap.

This may mean then that the primary erosion was from ice and CO2. Some
channels are found north of *South Pole 3* in Arabia Terra, but these
may be from the Hellas impact later when the pole moves again. If so
then this would again imply the temperatures and air pressure were too
low after Margaritifer Sinus for water erosion. More investigation of
this polar route should confirm whether channels existed.

The ice deposit at *South Pole 3* abuts a cliff to the north, which is
an extension of the dichotomy boundary. This ice then implies that it is
connected to the creation of this cliff and by extension created the
cliff of the dichotomy boundary as the pole moved. As water ran down the
slope at *South Pole 3* it would have eroded the ground, but where the
ground was permanently frozen the ground would have been protected. This
should then give a boundary to the north of the moving pole where the
ground slopes more.

The speed of the polar wander should be according to how quickly the
Tharsis Montes and Olympus Mons grew, with their tendency to go to the
equator. Also as the pole moved away from Argyre it may have been held
back because the negative mass of the Argyre impact basin would tend to
be near the pole. As it came closer to the Utopia and Isidis impact
basins it may have accelerated, releasing more water. These basins would
counteract to some degree the negative mass of Argyre as they too would
seek to be near a pole. It may also be that with the polar movement the
channels would be regularly changing and so did not form as large as in
Margaritifer Sinus.      

*The Hellas Impact*

The Hellas basin is centred at approximately 40S and 290 W. This would
have made it about 40 degrees from *South* *Pole 3* and so would have
been an oblique impact, though not as much as Argyre. Almost exactly
opposite Hellas is Alba Patera, again probably formed from the shock
waves. The resultant shock waves may again have gone around Mars
stimulating volcanism, perhaps restarting Tharsis Montes and Olympus
Mons which are also close to opposite Hellas. It may also have stopped
Mars’ magnetic field. Sprenke and Baker[107] <#_ftn107> point out that
the rotational poles closely follow the movement of *Pole 2* to *Pole
3*, but this does not appear to extend to *Pole 4*. This may be because
the Hellas impact stopped the magnetic dynamo with the shock waves.

Anderson et al[108] <#_ftn108> analysed Syria Planum in comparison to
Alba Patera. They concluded Syria Planum is Noachian to late Hesperian
with intense activity that declined later. This would be consistent with
its initial formation from the Isidis impact and later from the Argyre
impact. They consider Alba Patera to be similar, which is plausible if
it was formed by the Hellas impact. This is considered to be extending
from the early Hesperian into the Amazonian and so is later than the
Syria Planum volcanism. They believe[109] <#_ftn109> that Syria Planum
had a greater impact on Tharsis than Alba Patera which is again
consistent with the impact sequence.

The large negative mass of Hellas would have tended to move the pole
towards it, and Sprenke found from elliptical craters that the pole
probably moved to 45S 345W.  This places it on the edge of the Hellas
Basin in the direction of the Argyre Basin, probably with the two
negative mass craters tending to both be near the pole. This is the same
as in *South Pole 3* where Argyre and Isidis basins were both near the
pole. It is closer to Hellas probably because Hellas is much larger than
the Argyre Basin, being younger. There are many large craters in this
area as well; some may also have been preserved through burial under the
polar ice. I call this *South Pole 4*.

In *Figure 10*[110] <#_ftn110> *A *is *South Pole 3* and *B* is *South*
*Pole 4*. This is now relatively close to *Pole 1* at 45S 68W. There is
approximately 83 degrees of longitude between *Pole 1* and *Pole 4*, and
they are on the same latitude.

Also in this pole position Isidis is on the equator which means that
*Pole 2,* Sinai Planum, and Tharsis Montes are also now on the equator.
The pole then has moved to near Hellas while maintaining much of the
weight of the Mons on the equator. This is consistent with the weight of
Olympus Mons and Tharsis remaining on the equator, and the pole moving
to the negative masses of impact craters.

Hellas is an oval shape approximately twice as long as it is wide[111]
<#_ftn111>, probably from the oblique impact. Since Hellas is
approximately 45 degrees from *South Pole 3* this would imply an impact
at 45N at the time, and the oval shape indicates an impact on the
western side to give the oblique angle pointing mainly at right angles
to *South* *Pole 3*. This is likely as to the west of Hellas there is a
reddish area[112] <#_ftn112> with much less ice, shown in *Figure
11*[113] <#_ftn113>. The icy area of *South Pole 3* is elongated
pointing along the path of the polar wander to *South Pole 4*. The
section west of Hellas basin much drier is shown as from *C* to *D*.
Since this is in a direct line with the longest part of Hellas it is
likely this was formed from ejecta or shock waves making this area
hotter for a long time, and eventually drying the area when *South Pole
4* moved. This is the same mechanism as might have happened with the
Argyre impact drying west and north of it in *Figure 6*[114] <#_ftn114>.

The icy blue area of the current South Pole reaches to Hellas and
implies the pole may have wandered east into Hellas and then south to
the current position, as shown in *Figure 13*[115] <#_ftn115>. The lack
of ice on *South Pole 3* may also indicate the climate was warmer from
the heat of the impact and stopped large amounts of ice forming.

The corresponding North Pole would then have moved to the east of Alba
Patera in Tempe Terra. There is a possible platform there similar to
that south west of Alba Patera. The pole may have moved as the
gravitational influence of Argyre lessened, with the basin filling up
and Elysium Mons growing larger. This would move *South Pole 4* to the
east away from Argyre, there may be another platform on the eastern side
of Hellas Basin. This would also be consistent with water gullies, which
in other parts of Mars are near former poles. If the pole moved to
eastern Hellas Basin this would explain gullies in Dao Vallis and Tempe
Terra. It may also be that the polar ice extended eastward to there.

This would also be consistent with the shape of the current poles.
Chasma Australe points to 270W and may have been formed by water melting
as the pole moved, the pole perhaps still moving. Promethei Planum would
also have been formed from the pole moving away from *South Pole 4*. A
hot spot creating basal melting may have formed Chasma Australe but the
moving pole could have also supplied the heat, the leading edge becoming
colder, and the trailing edge warmer.

Hellas seems to have contained ice covered lakes which would be
consistent with being near a pole. It can be seen that the moving pole
may have made a lot of different areas appear to be ice rich and often
to have fluvial flows, even glaciers and hydro volcanism. This could
solve the mystery of why Mars has so many water signs and apparently not
enough ice available to cover them all. It also can explain that even
though the temperature has likely been too low for liquid water,
channels are widely seen. The moving pole would have moved water and ice
with it affecting each area in turn, looking as if there should be
perhaps 10 times as much water on Mars.

Chemically Mars resembles a dry planet[116] <#_ftn116> so outside of
these poles there may have been little ice or water, and CO2 erosion may
even have predominated at times[117] <#_ftn117>. Each impact would have
temporarily heated up the planet giving perhaps brief times of liquid
water and perhaps higher air pressure through sublimated gases.

The various Mons might have been periodically restarted from shock waves
from the impacts and the resulting heat kept the planet warmer for a
time, until eventually all volcanic activity ceased and Mars reverted to
the cold planet we see today.

Thomson and Head[118] <#_ftn118> believe glacial features, moraines,
drumlins, and eskers are to be found in Hellas, consistent with being
near a pole. According to them this could have been part of an ice
sheet[119] <#_ftn119> and a proglacial lake[120] <#_ftn120>, possibly
middle Amazonian[121] <#_ftn121>. The lake they believe would have held
enormous amounts of water that has disappeared, consistent with water
from a pole that moved on.

Jakupova et al[122] <#_ftn122> have laid out a distribution of craters
10 km and over. This boundary of heavy cratering closely follows the
movement from *Pole 2* to *Pole 3* and indicates when the resurfacing of
the north may have occurred at this time.

This is consistent with the poles moving water and sediments northwards,
and burying craters. There is an area above Margaritifer Sinus which is
nearly devoid of craters; this is likely to have been resurfaced in the
floodwaters in the movement of *South Pole 2 *to* South Pole 3*. Isidis
is comparatively devoid of craters, and this continues in a line with
the movement of *North Pole 2 *to *North* *Pole 3*. This would again be
from transporting sediments and water north and removing craters. The
area north of the equator and 60 degrees west extends high into the
northern hemisphere with heavy cratering. This area was found by Odyssey
to be drier and indicates that a lack of water is associated in this
area with cratering.

Layers are Mars are thought to have been formed by dust alternating with
CO2 or water ice. As water and ice were moved north by the movement of
*Pole 2* to *Pole 3* it would have deposited on these layers. With this
pressure and with liquid water the tendency would be for the CO2 and ice
to melt and move upwards, which would make the layers collapse and the
ground to lower in elevation. The movement of water northwards then
could have created a lowering of the ground forming the Northern
lowlands. This lowering in turn would enable a large sea, ice sheet or
mud ocean to form and the collapsing of layers to become more and more
widespread. If so then the southern hemisphere may have substantial
amounts of CO2 and ice still trapped in layers.

The northern hemisphere is seen as Amazonian and the Southern surface as
Hesperian implying the southern hemisphere is older. This is however
from crater counts and it is possible that the craters in the northern
hemisphere may have been removed and buried in this process.

After the Argyre impact the formation of the volcanoes may have added a
lot of ash into the atmosphere which would have tended to collect at the
cold trap in the poles. This would have subsequently been moved
northwards as the poles moved.

Permanent ice in the north[123] <#_ftn123> would tend to compress the
ground leading to polygons when the ice was eventually removed. Dust and
accretion from meteors would have built up on the northern ice as well
as in the south. As meteors impacted in the north they would have fallen
on ice and so not left a permanent mark. Head et al[124] <#_ftn124> show
that the northern lowlands contain areas of polygons, craters with
ejecta lobes, and potential coastlines.

Deviations in the Contact 2 coastline may be accounted for by changes in
Tharsis and Elysium Mons which would be occurring as the pole moved, and
later.

When eventually the planet became colder after the effects of Hellas and
Tharsis wore off the air would have begun to freeze and go to the poles.
Then the northern ice would also have sublimated, some may even still be
buried as a frozen ocean. The material that had built up on the northern
ice would have fallen down onto the craters that had been preserved
under the ice, and buried some of them. This material would appear
similar to that of the south, and likely not show signs of water as it
came from the surface above the ice. Some of the northern ice sheet may
have been liquid underneath around Tharsis Montes, Olympus Mons, Alba
Patera and Elysium Mons because of their heat.

Some of these surfaces then may be smooth from having been sediments on
an ocean floor in this way. Others areas may be smooth because as the
ice sublimated the material fell smoothly.

In two areas ice seems to follow the dichotomy boundary, shown in
*Figures 14*[125] <#_ftn125> and *15*[126] <#_ftn126>. This may be a
residue from the movement of the polar ice from *Pole 2* to *Pole 3*.

Amazonis Planitia is thought to be flat from sedimentation or fluvial
processes according to Head[127] <#_ftn127>. This is north of where
*North Pole 3* stopped. Also the outflow channels may be partially from
when *South* *Pole 2* in Syria Planum melted and began moving. Arsia
Mons which is the most southern of the three Tharsis Mons may have been
much smaller then. Some channels leading to Amazonis Planitia point
north but to the east some point more to the North West.

Lucas Planum[128] <#_ftn128> is described by Cabrol et al[129]
<#_ftn129> as an estuarine delta. If so then this may imply that the
movement of *Pole 2* to *Pole 3* was accompanied by water flows as the
pole melted. It may also have formed water locally from the heat of
Apollinaris Patera[130] <#_ftn130>, or from when the pole began to move
north towards the future site of Alba Patera after the Hellas impact.
Alba Patera has steep sides and may have formed in the polar ice of
*North Pole 4*. Fuller et al[131] <#_ftn131> believe this area was
resurfaced volcanically and with fluvial sediments. This could be for
example from when the Hellas impact restarted some volcanism in Olympus
Mons and started melting and moving *Pole 3*.

The Medusa Fossae Formation follows the path of *Pole 2* to *Pole 3*,
and has formations similar to a pole according to Fuller et al[132]
<#_ftn132>.  

McGill[133] <#_ftn133> refers to the younger material sitting on the
older Noachian material, which is consistent with the dust layer
settling. The buried materials are similar in age to the southern
highland, which is consistent with the idea that this was buried under
ice and then overlain with dust as the ice sublimated. In this case the
air pressure would already be low so there would not be a liquid phase,
hence no water to leave signs of the removal of the ice and chemical
signs of water having been there.

Watters[134] <#_ftn134> shows lobate scarps are found south of the
dichotomy boundary suggesting that compressional deformation was
involved in the boundary’s formation, which is consistent with the
weight of polar ice. While he suggests that this occurred in the early
Hesperian Anderson et al[135] <#_ftn135> believe Alba Patera was also
formed in the early Hesperian to Amazonian, but the impact of Hellas may
have defined the start of the Amazonian from the Hesperian. Since the
Noachian, Hesperian, and Amazonian are calculated from crater records
the impact of Hellas here may have changed these same crater records of
the Hesperian to Amazonian at least around Alba Patera.

Head et al[136] <#_ftn136> believe much of the northern lowlands were
resurfaced volcanically and in some areas as sublimation residue from
frozen ponded bodies of water[137] <#_ftn137>. This may have occurred by
the diffusion of shock waves from the Hellas impact over the northern
hemisphere of *Pole 4*.

Tanaka et al[138] <#_ftn138> believe the northern lowlands were smoothed
by glaciation. This would be consistent along the dichotomy boundary
while it was forming, if there was a larger icy area north of the moving
pole that was melting and reforming. If the air pressure was too low
then this could have been from ice sublimating.

Hoffman et al[139] <#_ftn139> believe flood channels from Cerberus Rupes
may be from CO2. This area is to the north as the pole moved southwards
from *North Pole 2* in Isidis Basin to the *North* *Pole 3* position.
This then may give CO2 through this area, in combination with flood
water from the melting pole. The actual flooding depends on the
temperatures but this area is equivalent to Margaritifer Sinus. *South
Pole 2* had begun moving and released water into Lunae Planum, Xanthe
Terra, and Margaritifer Sinus, so the opposite pole would likely be
releasing water at the same time as it moved.

Since CO2 typically sublimates on the current poles in summer this same
mechanism would presumably be operating as the pole passed this area. It
is not known at this stage whether CO2 can account for these effects,
but it is likely that it was available.   

Burr et al[140] <#_ftn140> believe flood water originates to the north
of the Elysium Basin and Marte Vallis[141] <#_ftn141>. A lake in Marte
Vallis may have been fed from Medusae Fossae to the south. Ice from the
pole moving to the *North* *Pole 3* position may have been heated by
Elysium Mons which would be forming from the Argyre impact, and so may
have provided heat to the area. They also conclude[142] <#_ftn142>
precipitation was unlikely to form the channels because nearby areas
show no erosion from rain. Groundwater is likely to form from a nearby
pole, and the heat from Elysium Mons should turn this to water when the
pole got close to the area.

Burr et al[143] <#_ftn143> see rootless cones though Athabasca Valles,
which can from lava on wet ground. This can be from the volcanic
activity from the Elysium Mons area caused by the Argyre impact, and
water from the passing pole. The carrying of sediments[144] <#_ftn144>
is consistent with the idea the moving pole may have carved out the
dichotomy boundary, and floods moving the sediment north. Ice from north
of Elysium Mons[145] <#_ftn145> may also have been melted by
volcanism[146] <#_ftn146> giving flood water.

Elysium Mons[147] <#_ftn147> according to Bowling[148] <#_ftn148> had
two periods of activity, which may correspond to the original formation
from the Argyre impact, and being reactivated by the Hellas impact.

The ice on the edge of *South Pole 3*[149]* <#_ftn149>* cuts off on the
dichotomy boundary as shown in *Figure 16*[150]* <#_ftn150>* which may
indicate the pole helped form the boundary.

While the pole was here each summer, water or ice may have fallen down
the slope of the dichotomy boundary off the northern edge of the pole,
and the dichotomy boundary here could have been the edge of the
permanent polar cap. The edge would form here because each summer water
or perhaps ice or CO2[151] <#_ftn151> avalanches would fall down the
slope, eroding it away till it abutted the permanently frozen cap. In
*figure 17* at *A* an ice trail, possibly from this water connects to
higher ice areas. With higher ground to the south water may have tended
to go north.

As the pole moved from *North Pole 3* to *North Pole 4* it moves close
to Olympus Mons and the Tharsis Montes, which may have restarted from
the shock waves of the Hellas impact. If so then the movement of the
pole near such hot areas should sublimate frozen CO2, so this time was
probably one of higher air pressure. As Alba Patera formed from the
Hellas impact at *Pole 4* the heat would also have kept CO2 from
freezing there and raised the air pressure. Since this would keep one
pole from having as much frozen CO2 the overall air pressure should have
been substantially higher for a long time.

This places the *North Pole 4* just to the north and North West of
Olympus Mons shown in *Figure 19*[152] <#_ftn152>*.* Milkovith et
al[153] <#_ftn153> interpret this area to the North West of Olympus Mons
to be glacial, but much large than terrestrial glaciers. This would be
consistent with polar ice. Each of the Tharsis Montes according to
Head[154] <#_ftn154> also shows glacial signs, perhaps from as the pole
was passing. Since a pole should slow as it nears its resting point
there may have been a pole on the Western edge of the Tharsis Montes for
some time.

*Pole 5*

This is the current Martian pole. As time progressed Alba Patera became
larger, perhaps cancelling out the negative mass of the Hellas basin.
The current poles have the major Mons all near the equator just as they
did at *Pole 3* and *Pole* *4*. This indicates that from the time of
*Pole 3* the polar wander had to move so as to keep these large masses
on the equator. Since *Pole 3*, *4*, and *5* are roughly in a straight
line this would have been controlled by the Mons and indicates they are
older than these three pole positions.

Pavonis Mons is on the equator and Arsia Mons the largest is at 10
degrees south. Olympus Mons is at 20 degrees North and Ascraeus Mons at
12 degrees north. Elysium Mons is at 25 degrees north.

Once the ice in the northern hemisphere started to sublimated and move
to the poles this would have created a large negative mass that would
have acted like a crater. The pole would have tended to move to the
gravitational centre of this which would move it from Hellas Basin to
the current position. Since most of the ice came from the north this may
explain why[155] <#_ftn155> [156] <#_ftn156> the *North* *Pole 5* has
more ice.

Since the shift to *Pole 5* temperatures may not have allowed this
additional ice to sublimate and equalise the amount at both poles.

Chasma Boreale on the *North* *Pole 5* points to approximately the
*North Pole 4*, and Chasma Australe on *South* *Pole 5* points
approximately to *South Pole 4*. Both of these are the largest chasma on
their respective poles. The poles may even still be moving which would
explain why the South Pole is asymmetrical[157] <#_ftn157>.

The North Pole seems similarly asymmetrical [158] <#_ftn158>. Both
shapes seem to elongate at right angles to the previous pole positions.
This would follow as the pole moved the forward edge would represent a
line of temperature low enough to form a permanent CO2 cap. Clearly the
elongation could not point into the movement of the pole as this would
be against the temperature gradient.

Byrne et al[159] <#_ftn159> found evidence of short term change on the
current Martian South Pole, in the “Swiss cheese” formations. This is
consistent with the idea that *Pole 5* is still moving, though it seems
unlikely such short term changes would be associated with the pole
moving. Changes may occur in spurts as areas collapse with the changed
temperatures. One analogy might be the changes in glaciers on the
Earth’s pole which can change suddenly from the slower global warming.

These structures are found on the forward edge of *South Pole 5*, and
the spider formations are found directly opposite this on the other side
of the pole. It may be then that these “Swiss Cheese” formations may be
older spider areas that have slowly been moved into colder areas and are
now permanently frozen. In this way the similarity between the Swiss
Cheese shapes and the spider bushes can be explained.

Some of the spider formations would then be left behind as the pole
moved on its trailing edge, and we see this as spiders that merge into
apparently inactive areas there.

Pathare et al[160] <#_ftn160> believe recent changes in the Polar
Layered Deposits may have been caused by changing obliquity though these
could also have been caused by the moving pole. Layering is seen along
the path of *Pole 2 *to *Pole 3*; implying layers may be formed as a
pole moves.

Malin Space Science Systems[161] <#_ftn161> recently reported in Science
more examples of changes on the South Pole. Hoffman[162] <#_ftn162>
shows gullies on the current South Pole may be undergoing changes, again
consistent with a moving pole. These pitted areas however are also
significant in relation to *South* *Pole 4*, and the gullies may have
been formed at that time. M1003736[163] <#_ftn163> mentioned by Hoffman
is at 70.91S 358.7W, which is closest to *South Pole 4*. This would
explain their pristine condition if they were moved into the polar area
after the pole shift from *Pole 4* to *Pole 5*.

*The Ages of Mars*

The three ages of Mars, Noachian, Hesperian, and Amazonian are primarily
based on craters counts. If the polar wander theory is correct then
these time scales will be distorted by resurfacing after each of the
four major impacts. The Argyre impact may have been so influential it
might be said to have begun the Hesperian, forming Valles Marineris,
Olympus Mons, the Tharsis Montes, the dichotomy boundary and Elysium Mons.

As an alternative guide the four impacts might themselves be defined as
the start of an age. There would then be the ages of Utopia, Isidis,
Argyre, and Hellas.  This can be much easier to work out the ages of
various formations as the beginning and end of each age is a fixed date.
Ages could also be defined according to volcanoes, e.g. the Age of
Tharsis, Olympus, Elysium, and Alba Patera.

An approximate age can be determined for each impact, and then a tree of
cause and effect can be created following on from each impact. Then the
age of each event that follows from an impact is determined and added to
the tree. This in turn enables the age of each impact to be more
precisely determined. Other events that were sufficiently independent
could be portrayed as separate trees of cause and effect.

The age of Utopia may have begun to form some of the area around Solis
and Bosporos Plana. There may also be areas to the north west of Elysium
Mons that could be dated according to this impact. It may have formed a
Mons that was destroyed by the Argyre impact, if so then signs around
the Argyre Basin may be dated according to Utopia as a benchmark.

Many of the effects of each impact would happen relatively soon
afterwards and there would be a long time between impacts dates. Many
formations should then be able to be connected with an impact and more
accurately determined. This is especially useful where each impact
changes an area in turn. For example the area around Tharsis Montes may
have been altered by all four impacts.

The age of Isidis could be initially estimated by comparing the relative
age of the Isidis and utopia Basins. This in turn may date some of the
changes to the Solis, Syria, and Sinai Plana, and perhaps earlier
changes to the future Tharsis and Valles Marineris. Geologically it is
easier to calculate the ages of these formations by showing how craters
counts are changed by resurfacing.

The age of Argyre may have formed the Tharsis Montes and Olympus Mons.
If so then craters on them may help date Argyre Basin. The beginnings of
Valles Marineris, Candor, and Ophir Chasma could be dated to shortly
after the Argyre impact. After this the water channels of Lunae Planum,
Xanthe Terra and Margaritifer Terra could be estimated.

In turn this can be compared against the age of the dichotomy boundary
which would be formed later. This may in turn allow the time of the
formation of the northern lowlands to be determined, if much was formed
after the Argyre impact.

The age of Hellas would move the pole from Lucus Planum northwards and
begin the formation of Alba Patera. This may also date the restarting of
Olympus Mons and Tharsis Montes from the shock waves of the impact. The
combined heat from these volcanoes may have resurfaced the northern
lowlands.

The current age may be dated from the time the existing poles were
formed.  

*Narrow angle images*

Previous poles have left many changes on the Martian surface. To examine
smaller scale changes I have examined 730 MOC narrow angle images[164]
<#_ftn164> out of a larger randomly acquired collection[165] <#_ftn165>,
separating them into various kinds of formations such as water signs,
dunes, and layers. These were accumulated over several years, before the
ideas in this paper were conceived so there is no relevant unconscious
bias in their selection.

*Fluid signs*

The collection of fluid signs[166] <#_ftn166> was first examined in
reference to *Pole 4*. This was done by converting the coordinates of
each image to its latitude under *Pole 4*[167] <#_ftn167>.

This gave a list of coordinates between 0, equal to 90 degrees old north
and 180 which is 90 degrees old south.

Fluid signs gave an unusual distribution[168] <#_ftn168> with a large
number clustering around the *Pole 4* equator. On further examination
these were around 37 to 43S and 140 to 200W, and 39N 19W.

The first cluster is on the bottom edge of an ice ridge area identified
by Odyssey[169] <#_ftn169>, which abuts the old equator at these
coordinates. This was previously identified as *Pole 3*. The second
cluster abuts another ice rich area on the top, again on the old equator
and also near the dichotomy boundary. This is at the opposite *Pole 3*.

The water could have several possible origins. Some ravines could have
formed on this pole, but this is unlikely as it should be very ancient
and the water flows are more recent[170] <#_ftn170>. The second
possibility is these flows occurred on the equator of *Pole 4* because
it was warm enough there for some water to melt from the remaining ice
of *Pole 3*. In that case we may be seeing relics of this flow. The
third possibility is we are seeing ice from *Pole 3* melting because the
current latitudes are suitable for this. In all cases this implies the
source of the water was ground water or ice in the soil from *Pole 3*.

Since the water only seems to have been flowing in small areas it seems
likely that these areas started flowing on the equator in *Pole 4* in a
restricted area close to the equator. Though the pole has shifted
channels in the ground are still connected to this ice, and at certain
mid latitudes this can still flow[171] <#_ftn171> [172] <#_ftn172>. As
we will see the positions of gullies is also correlated with
layering[173] <#_ftn173> relative to *Pole 4*. Hartmann et al[174]
<#_ftn174> compare these gullies with Icelandic gullies, which is
consistent with the idea of seepage from a former polar area.

Others seem to cluster around 35S 270W, and 29S 38W. The first cluster
is on the north eastern edge of Hellas Basin and may represent an area
on the eastern edge of the *South Pole 4* ice cap.

The second cluster is close to the south western edge of the *South Pole
3* ice cap and so is likely to have formed with the same mechanism. This
then gives all 4 main clusters the same mechanism, of ice from an old
pole now at mid latitudes suitable for a water flow.

Another cluster is at 37 to 53S 320 to 356W. This is close to *South
Pole 4*. Again the mechanism seems to be a part of the ice from an old
pole position which corresponds to the suitable latitude for water to
flow now.

It would seem then the reason the craters with water signs are so rare
is that old polar ice deposits and suitable current mid latitude
temperatures only coincide at a few positions.

Schmidt[175] <#_ftn175> points out additional areas with craters, which
are also examined.

Gorgonum Chaos[176] <#_ftn176> [177] <#_ftn177> is situated at[178]
<#_ftn178> 37S 173W, which would be on the southern edge of *North*
*Pole 3*. Wilson et al[179] <#_ftn179> believe these gullies are not so
young and represent only a limited discharge. This would be consistent
with the older position of *Pole 3*, which still had to move to *Pole 4*
and on to the current *Pole 5*. One theory according to Moore et al[180]
<#_ftn180> is that these knob fields were formed by water and near a
lake, which would also be consistent with a previous *Pole 3 *position.

Stewart et al[181] <#_ftn181> examine the idea that CO2 could have
formed these channels, which is also consistent with a pole position.
This would depend on the temperatures of *Pole 3* at the time. As seen
earlier the pole may have cooled in its movement from *Pole 2*, as the
number of channels may have diminished. The temperatures may have risen
after the Hellas impact as the Pole moved northward to the *North* *Pole
4* position around then to be formed Alba Patera. Many of the objections
to CO2 arise from not having a mechanism to maintain enough of it long
enough to create these formations, however a pole may be able to supply
this reservoir. There may be then in some of these areas a mixture of
the two kinds of erosion[182] <#_ftn182>, without knowing the
temperature at the time it is probably not possible to determine. Other
ravines may be more recent[183] <#_ftn183>.

Newton Crater[184] <#_ftn184> is situated at 41.1S 159.8W, also on the
edge of the *North* *Pole 3* area. Cabrol et al[185] <#_ftn185> refer to
the large amounts of water released into Newton Crater, which represents
the dilemma of abundant water on such a dry planet. Being on the edge of
a pole however could supply this water while non polar areas could
remain dry.

Tempe Terra[186] <#_ftn186> [187] <#_ftn187> is found at approximately
42N 73W. This area would again have been on the edge of an ice cap, in
this case *North Pole 4*. Volcanism[188] <#_ftn188> in the area may have
come from the Hellas impact, like Alba Patera. Hauber et al[189]
<#_ftn189> point out chaos similar to Gorganum Chaos, which is also on
the edge of a former pole. Syria Planum, associated with *South Pole 2*
also has these formations. Even though these three formations are
relatively close to each other, each could have been formed from a
different pole. They also show signs of glaciation, which is consistent
with the edge of a pole.

Nirgal Vallis[190] <#_ftn190> [191] <#_ftn191> is approximately at[192]
<#_ftn192> 27.5S 317W, on the edge of *South* *Pole 4* near Hellas
Basin. This may account for its appearance of having water more
recently. Lee and Rice[193] <#_ftn193> compare Nirgal Vallis to Devon
Island, and find indications of the decay and retreat of an ice cover,
consistent with the edge of a Martian *South Pole 4*.

Hale Crater[194] <#_ftn194> [195] <#_ftn195> is located at 36S 37W. This
may have experienced outflows from Argyre basin when *South* *Pole 2*
was moving eastward. Alternatively it could have received water from
*South Pole 1* and the movement to *South Pole 2*. This could have been
a slow movement and generated a lot of water in this area.

Maunder Crater is on the south western edge of *South Pole 4*.

Rabe crater is situated at 44S 325W, which is around the area of *South
Pole 4*.

Dao Vallis is located at 33S 266W, on the north eastern edge of *South
Pole 4*. Arfstrom[196] <#_ftn196> interprets the area as glacial, which
is consistent with being on the edge of a pole. He believes[197]
<#_ftn197> this may be part of a larger ice flow.

All these areas[198] <#_ftn198> referred to by Malin et al are on
previous pole positions. This makes it likely groundwater rather than
snow is the cause of these gullies and viscous flow features[199]
<#_ftn199>, though snow[200] <#_ftn200> [201] <#_ftn201> may also be
forming more easily in shapes made by flowing water. In some cases
CO2[202] <#_ftn202> from previous poles may also have formed gullies.

Schorghofer et al[203] <#_ftn203> map locations of slope streaks, and
one cluster is approximately on *South* *Pole 3*. This may imply they
are indeed related to water. Other areas tend to follow the path of the
opposite *North Pole 2* to *North* *Pole 3*, and then part of the
movement to *North Pole 4* around Alba Patera. Residual ice in the soil
may also make it conducive to landslides.

Palermo et al[204] <#_ftn204> believe these are more likely to be fluid
flows. No actual gullies seem to be formed with streaks though a fluid
reservoir implies they should flow over and over at least sometimes. The
shapes probably represent the path to lower elevations water or dust
would take.

Over time water should make some kind of mark or channel on the surface
like we see in even in Russell Crater on sand. Moisture from underground
ice deposits could cause landslides, and explain the link between old
pole areas and the streaks. Sullivan et al[205] <#_ftn205> point out the
streaks are similar to snow avalanches, which may be consistent with icy
soil under a dusty surface layer. It may be fluid flows and dust
avalanches both occur at times. Sullivan et al[206] <#_ftn206> refer to
dust avalanches as the most likely explanation.

Another possibility is a small area of ice sublimates and the resulting
vapour dislodges some dust and creates the landslide. If so then an
example of this may have been imaged. MOC photo AB102003[207] <#_ftn207>
shows a possible plume of vapour found by Spires, colloquially known as
“Dan’s smoker”[208] <#_ftn208>. There is a slope streak in this image
pointing in the same direction, and other images in the area such as
M2300332[209] <#_ftn209> contain slope streaks. The pale mark seems to
go down one mound and then climb the other, which makes it unlikely to
be a streak.  If this was reimaged and the light streak was gone then it
is more likely to have been vapour. E1103683[210] <#_ftn210> just misses
this formation.

Hematite[211] <#_ftn211> has been found in the area of *South Pole 3*,
which is consistent with the having water around a polar area. The area
is believed to have been recently exhumed, by Lane et al[212] <#_ftn212>
which is consistent with the pole moving and exposing this area.
According to Hynek Aram Chaos and Valles Marineris[213] <#_ftn213> [214]
<#_ftn214> also have hematite deposits, which is consistent with the
path of the moving pole from *South Pole 2* to *South Pole 3* giving
water to create hematite. Aram Chaos[215] <#_ftn215> is to the west of
the *South Pole 3* position and is connected to the Areas Valles outflow
channel. This would also be consistent with the pole depositing water as
it moved.

*Dunes*

Images of dunes[216] <#_ftn216> were also compared to their *Pole 4*
latitudes[217] <#_ftn217>. Dunes were generally found to be evenly
spread around the current pole longitudinally and to be confined within
40 degrees north and south of the current equator. The distribution in
regard to *Pole 4* was also even but generally from 50 degrees north to
50 degrees south. This is an usual correlation as *Pole 4* is at 45
degrees south, and so the distribution should be skewed. This implies
that dunes formed in a band between 50 degrees old north and 50 degrees
old south in relation to *Pole 4*. In turn this implies[218] <#_ftn218>
a high enough air pressure for dunes to form at the time. After the pole
shift the dunes would appear to be moving to the same kind of formation
relative to *Pole 5*.

Dunes on the current *South Pole* *5* were also examined[219]
<#_ftn219>. These dunes were typically found between 75 to 85S and 100
westward to 350W. In relation to *South* *Pole 4* all of these dunes
were found to be between 30 and 50 degrees old south (that is, south
compared to *Pole 4*) which implies they were actually formed before the
Pole shift of *Pole 4* to the current *Pole 5*. If so then these dunes
may have been frozen in position since then. Malin et al[220] <#_ftn220>
say there is no evidence dunes on Mars are presently mobile.

*Layers*

Layer images[221] <#_ftn221> were also examined[222] <#_ftn222> and
mainly fell in the old southern hemisphere of *South* *Pole 4*,
particularly from the equator to 50 degrees old south (old south is
relative to *Pole 4*). This is surprising as it implies much of the
layering shown was actually formed under *Pole 4* though earlier layers
may be buried.

Layers found on the current South Pole, *Pole 5*, were typically at 85S
and concentrated at 175 to 275W. This in relation to *South Pole 4*
placed them between 30 and 50 degrees old south, also implying they were
formed in the time of *Pole 4* rather than on the current pole. Malin et
al[223] <#_ftn223> point out layers in Candor Chasma, which is near the
equator of *Pole 4* seems relatively young compared to nearby Arsia
Mons. The absence of craters may imply these layers were made in the
time of *Pole 4*, or perhaps exhumed by processes in that time.

If so then much layering[224] <#_ftn224> has been a relatively recent
occurrence associated with the Hellas impact, perhaps because older
layering may have been buried. *Pole 4* may have existed for long enough
for layers[225] <#_ftn225> under it to dominate.

Dunes and layers have a similar distribution in the southern hemisphere
of *Pole 4*, while water signs seem to be related to different poles. It
may be then that air rather than water is responsible for many of these
layers. CO2 may also have formed some layers, if the temperature dropped
enough. The change from *Pole 4* to *Pole 5* may have occurred when the
temperature dropped enough to freeze the air, so ice sublimated and went
to the poles

If the air pressure dropping was enough to make the pole move to *Pole
5* then that implies it had not dropped to that level earlier, or the
pole shift would have already happened. The dropping of the temperature
then may have represented a final phase change, or the temperatures may
have periodically risen with changing obliquity. If so then the pole may
have wandered[226] <#_ftn226> to some degree between the positions of
*Pole 4* and *Pole 5* depending on the level of ice depositions in the
northern lowlands.

In this time CO2 may have been involved in the formation of layers[227]
<#_ftn227>. Odyssey thermal data[228] <#_ftn228> implies layers were not
formed by water. Layers are found in the area of *Pole 3*[229]
<#_ftn229>, which may have formed in that time just as some layers form
on the poles today. Layers could have formed under all the previous
poles; it may be that *Pole 4* dominates because it is the most recent.

Some layers may have been formed in the movement of *Pole 2* to *Pole
3*, and because this is on the dichotomy boundary this will appear in
the equatorial region of *Pole 4*. Also since Tharsis Montes, Olympus
Mons, Hecates Tholus, Elysium Mons and Alba Tholus all are near the
*Pole 4* equator in the time ash may form layers also appearing to be
caused by *Pole 4*. Some layers may also have been formed along the
equatorial region of *Pole 4* by water if the temperature was high enough.

In terms of astrobiology the impacts certainly warmed Mars, and
depending on their timing may have created a climate that could have
supported life for long periods.

In an ideal scenario the Utopia impact would have heated the planet for
a long time, as ice and CO2 forming in the Utopia Basin would have been
warmed. Since even now Mars is close to being warm enough to sublimate
all the CO2 from the poles it is reasonable to believe that this impact
basin at the pole would have made it warm enough to raise the air
pressure, especially with higher obliquity[230] <#_ftn230>.

If the Isidis impact occurred before the planet cooled then this would
have added heat, as *Pole 2* forming on Isidis Basin would have
sublimated CO2, as would the pole opposite it around Solis and Syria Planum.

Next the Argyre impact may have warmed the poles followed by the Hellas
impact. If these were spaced at the right times then Mars may have had a
long time of higher air pressure and occasional liquid water. These
conditions would possibly have allowed microbial and even substantially
more evolved life forms to survive, especially since the higher air
pressure would have offered some protection from radiation. An impact
may have decimated life much like impacts did on earth[231] <#_ftn231>
but subsequently kept the planet warm enough for the survivors to adapt.
If the Hellas impact destroyed the Martian magnetic field then this
could have led to the extinction of some life. Without sufficient life
to create oxygen this may have led to the air freezing more as CO2 and
ice sublimating to the poles.

Eventually the impacts and volcanoes ceased and life if it still or ever
existed would have had to adapt to the much colder climates.

The more likely scenario is that life may have evolved somewhat during
these times of higher temperatures only to die off or survive at a low
level when the planet cooled and the air froze. With the next impact
some life may have evolved again if the times were long enough, perhaps
being reseeded with meteors from Earth.

*Conclusions*

* *

Much of the Martian terrain is consistent with the idea of polar wander.
This may have been controlled by 4 main impacts, Utopia, Isidis, Argyre,
and Hellas.

The Isidis impact may have formed some of the deformations around Solis
and Syria Planum.

The impact of Argyre may explain the formation of the Tharsis Montes,
Olympus Mons, Elysium Mons, Hecates Tholes, and Alba Tholus.

The movement of *Pole 2* to *Pole 3* may explain the formation of the
dichotomy boundary and all the fluid channels north of it. It may also
have formed the Northern Lowlands.

The number of narrow angle images examined here is too small to give a
definite conclusion, but they give a picture of *Pole 4 *having a large
influence on many current Martian features. This may be an artefact of
the selection process but they were accumulated well before the ideas in
this paper.

Fluid signs in craters and valleys are found on the edges of older
poles, which are now at suitable latitudes for water ravines to form.

Some dunes are found to be evenly spread compared to *Pole 4*, even on
the current *South Pole 5* and imply a time of higher air pressure, and
perhaps that since then there has been insufficient air pressure to move
them from this pattern.

Layering may have partially occurred in the time of *Pole 4*, and some
layers on the current South Pole may be from before the pole shift to
*Pole 5*.

* *

------------------------------------------------------------------------

[1] <#_ftnref1> Bradley J. Thomson and James W. Head III “Utopia Basin,
Mars: Characterization of topography and morphology

and assessment of the origin and evolution of basin internal structure”
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. 0, PAGES 1–22, MONTH 2001
http://www.planetary.brown.edu/planetary/documents/2396.pdf

See Figure 1, comparing Utopia Basin with Hellas Basin.

[2] <#_ftnref2>NASA, Jack Connerney, Mario Acuna, Carol Ladd “Martian
Magnetic Map”

http://www.solarviews.com/cap/mgs/magmap.htm

[3] <#_ftnref3> “The northern hemisphere is made up largely of rolling
volcanic plains, not unlike the lunar maria. These extensive lava
plains—much larger than those found on Earth or the Moon—were formed by
eruptions involving enormous volumes of lava. They are strewn with
blocks of volcanic rock as well as with boulders blasted out of impact
areas by infalling meteoroids (the Martian atmosphere is too thin to
offer much resistance to incoming debris). The southern hemisphere
consists of heavily cratered highlands lying several kilometers above
the level of the lowland north.”

“On the basis of arguments presented in Chapter 8, this smoother surface
suggests that the northern surface is younger.
<http://astronomy.nju.edu.cn/astron/AT3/AT30804.HTM>(Sec. 8.4) Its age
is perhaps 3 billion years, compared with 4 billion in the south. In
places, the boundary between the southern highlands and the northern
plains is quite sharp. The surface level can drop by as much as 4 km in
a distance of 100 km or so. Most scientists assume that the southern
terrain is the original crust of the planet. How most of the northern
hemisphere could have been lowered in elevation and flooded with lava
remains a mystery.”

Nanjing University Syllabus “The Surface of Mars available online at

http://astronomy.nju.edu.cn/astron/AT3/AT31004.HTM

[4] <#_ftnref4> “Major features of topography. The dominant feature of
the topography is the striking difference (;5 km) in elevation between
the low northern hemisphere and high southern hemisphere that represents
one of the outstanding issues of martian evolution. This hemispheric
dichotomy also has a distinctive expression in the surface geology of
Mars. The surface of the crust in the southern hemisphere is old and
heavily cratered,

whereas that in the north is younger and more lightly cratered and was
probably volcanically resurfaced early in Mars’ history (17). The

hemispheric difference is also manifest in surface roughness (Fig. 3)
calculated from the MOLA topographic profile data (18). Most of the
northern lowlands is composed of the Late Hesperian–aged (19) Vastitas
Borealis Formation, which is flat and smooth (Fig 2), even at a scale as
short as 300 m (Fig. 3). The Amazonian-aged (19) Arcadia Formation,
which overlies the Vastitas Borealis Formation, is also smooth at large
and small scales, consistent with either a sedimentary (4, 20) or
volcanic (21) origin for these plains. In the southern hemisphere
Noachian aged (19) ridged plains form locally flat intercrater deposits,
whereas younger Hesperian- aged ridged plains dominate in some regions.
All are characterized by a rougher topography than the northern plains.
The boundary between the smooth northern hemisphere and the rough
southern hemisphere is characterized by mesas, knobs, and intervening

plains (22), as well as regional elevation changes of up to 4 km over
distances of 300 to 1300 km (23). Where the regional elevation change is
relatively steep, it is referred to as the dichotomy boundary scarp
(compare Fig. 1).”  Smith, D.E. et al “The global topography of Mars and
implications for surface evolution” Science
<http://www.sciencemag.org/>, 284, 1495-1503, 1999 available online at
http://ltpwww.gsfc.nasa.gov/tharsis/global_paper.html  

[5] <#_ftnref5> “Very roughly speaking, this is a map of the ages of the
surfaces on Mars. The red surfaces were formed in period 1, the green
surfaces were formed in period 2, and the blue surfaces were formed in
period 3. These three periods correspond roughly to the three Martian
periods Noachian, Hesperian, and Amazonian (named after regions that
approximate those ages.)” Mike Caplinger” Determining the age of
surfaces on Mars” Malin Space Science Systems February 1994 available
online at http://www.msss.com/http/ps/age2.html [16/8/03]

[6] <#_ftnref6> Jarmo Korteniemi “Main albedo features and full
nomenclature” available online at
http://www.student.oulu.fi/~jkorteni/space/mars/maps/ [16/8/03]

[7] <#_ftnref7> USGS Astrogeology Research program Regional MOLA map
available online at

http://planetarynames.wr.usgs.gov/images/mola_regional.pdf

[8] <#_ftnref8> K. F. Sprenke and L. L. Baker “POLAR WANDERING ON MARS?”
Lunar and Planetary Science XXXI 1930.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1930.pdf

[9] <#_ftnref9> Aviation Now “Water Find Will Shape Mars Exploration
Plan” available online at
http://www.aviationnow.com/content/publication/awst/20020603/aw32.htm

[10] <#_ftnref10> “Gravity over the north polar region (Fig. 4A) reveals
several positive anomalies that have no obvious correlation with
topography (16). A combination of ice and crustal material has been
proposed (17) to account for anomalies situated in the immediate
vicinity of the north polar layered terrains. In contrast, the south
polar region (Fig. 4B) shows a positive anomaly of ;200 mgal immediately
over the pole, which

could represent the load associated with the permanent ice cap. The lack
of a comparable anomaly over the northern cap could indicate that the
southern cap is younger and has not yet had sufficient time to adjust
isostatically, or that the southern layered deposits contain a larger

fraction of dust, thus constituting a greater gravitational load than in
the north (12).

A possible explanation for the high-latitude northern hemisphere gravity
anomalies, adjacent to and remote from the residual ice cap, is that
they represent moderate-diameter (100 km) impact basins buried beneath
the resurfaced northern hemisphere (18). The mass excesses implied by
these positive anomalies may represent a combination of volcanic and
sedimentary fill within the basin cavity and thinning of the northern
hemisphere crust beneath the basin (19) that have not relaxed to an
isostatic state (20).” David E. Smith et al “The Gravity Field of Mars:

Results from Mars Global Surveyor” available online at

http://ltpwww.gsfc.nasa.gov/tharsis/smith.mgs.grav.pdf

[11] <#_ftnref11> “We find evidence for several probable buried basins
in the lowlands and at least one in the highlands that are similar to
Hellas, Argyre, Isidis, Chryse and Utopia in size. All of these buried
features must be extremely old because smaller likely buried basins are
superimposed on them. We previously used this relationship to suggest
Utopia was "Earliest" Noachian in age.” FREY, Herbert V
<mailto:frey at core2.gsfc.nasa.gov> “LARGE BURIED AND VISIBLE BASINS ON
MARS: TOTAL POPULATION AGES OF THE HIGHLANDS AND LOWLANDS”

http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_44774.htm

[12] <#_ftnref12> http://www.harmakhis.org/history/1.jpg

[13] <#_ftnref13> “Abstract. Recently obtained Mars Orbiter Laser
Altimeter (MOLA) topography has permitted a new assessment of the
morphology, structure, and history of Utopia Planitia. The new
topographic data convincingly demonstrate that the Utopia region is an
impact basin, as originally proposed by McGill [1989], whose major
topographic expression is a circular, 1–3 km deep depression _3200 km in
diameter. Utopia Basin is the largest easily recognizable impact
structure in the northern hemisphere of Mars and is the only portion of
the northern lowlands that exhibits a distinct large-scale impact
signature; its presence there and its ancient age verify that a
significant part of the northern lowlands dates back to the Noachian
period.” Bradley J. Thomson and James W. Head III “Utopia Basin, Mars:
Characterization of topography and morphology

and assessment of the origin and evolution of basin internal structure”
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. 0, PAGES 1–22, MONTH 2001

http://www.planetary.brown.edu/planetary/documents/2396.pdf

[14] <#_ftnref14> “After Isidis, the largest impact-associated gravity
anomaly (Table 2) is Utopia (Fig 5A), which has been interpreted as an
ancient basin on the basis of surface geology (24). Topographic data
indicate that the basin is a quasi-circular depression;1500 km in
diameter (25), a factor of about 2 greater than originally proposed.
Utopia’s gravity anomaly

is diffuse, occupying an area of ;107 km2 with no clear centre. The
Utopia structure is buried beneath the northern hemisphere resurfacing,

but the size of the depression and gravity anomaly suggest that the
original basin could have been of a size comparable to that of Hellas
(Fig. 5B) (16). However, these two massive structures appear in complete

contrast gravitationally. Both appear to have readjusted isostatically,
but Utopia was subsequently filled with material, which contributes

to the gravitational mass excess. If the Utopia and Hellas structures
were originally similar, the gravity field data may be able to shed
light on the density of the material that has filled Utopia and by
inference on the material of the northern plains.” David E. Smith et al
“The Gravity Field of Mars: Results from Mars Global Surveyor” 1 OCTOBER
1999 VOL 286 SCIENCE www.sciencemag.org <http://www.sciencemag.org/>
available online at

http://ltpwww.gsfc.nasa.gov/tharsis/smith.mgs.grav.pdf

[15] <#_ftnref15> “8.5. Open Water Features

Parker et al. [1989] presented evidence for as many as seven

contacts between the northern plains and southern uplands, which

were interpreted to be highstands of a former ocean. On Earth,

wave-cut platforms and associated landforms result from direct

coupling of wind and the open water surface [Duane et al., 1972;

Swift et al., 1972, 1973; Stubblefield et al., 1975; Swift, 1975;

Rice, 1994]”

“

8.6. Ice-Dominated Bodies of Water

A second possible analog for the circumferential features

includes the extremely wide, near-horizontal platforms that are

common in high-latitude regions on Earth. Known as strandflats,

they are up to 50–60 km wide and have extremely low crossplatform

gradients [e.g., Evers, 1962; Benn and Evans, 1998].

There have been many theories advanced for their formation, but

many workers have highlighted the importance of frost shattering

[Nansen, 1904, 1922; Larsen and Holtedahl, 1985; Guilcher et al.,

1994]. Frost action resulting from recurrent freeze-thaw cycles is

an effective geomorphologic agent and is considered to be a key

component of rapid coastal cliff recession and platform extension

in polar seas [Hansom, 1983; Matthews et al., 1986]. The most

extensive strandflats are found in areas sheltered from wave

erosion [e.g., Hansom, 1983]. An ice foot, or accumulation of

sea ice frozen onto the shoreline, inhibits erosion by wave action

during freeze periods but may increase the potential for frost

shattering at the base of coastal cliffs [Nansen, 1922; Feyling-

Hanssen, 1953; Nielsen, 1979]. Exposure of the coastline to wave

action during thaw periods may increase the rate of platform

formation by facilitating the removal of debris [Matthews et al.,

1986]. An idealized cross section of terrestrial strandflat generations

is given in Figure 12. Note that the sequence of landforms

shown is of similar scale to the circumferential features shown in

Utopia [see also Rice, 2000].” Bradley J. Thomson and James W. Head III

“Utopia Basin, Mars: Characterization of topography and morphology

and assessment of the origin and evolution of basin internal structure”
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. 0, PAGES 1–22, MONTH 2001

http://www.planetary.brown.edu/planetary/documents/2396.pdf

[16] <#_ftnref16> “Viking Orbiter and Mars Orbiter Camera images show
mesas having horizontal to angled layers in many Valles Marineris
chasmata. Several chasmata are filled nearly to the plateau rim with
Late Hesperian to Early Amazonian [1] interior deposits, many of which
are separated from

the chasmata walls by a moat. A lacustrine origin was suggested because
of their apparent horizontal continuity and similarity in connected
troughs [2,3,4,5,6,7]. Others prefer a volcanic origin based on the
volcano-tectonic setting, layer diversity, low albedo and high
competence of some layers, tuff-like weathering, and location of dark
materials [1,4,8,9]. The interior deposits of Gangis and Juventae
Chasmata were suggested to be similar to the ideal tuya form
(table-like) 10] and eroded flutes and variable albedo of Hebes Chasma
deposits bear an uncanny resemblance to tuyas [11]. We note that Mars
Orbiter Laser Altimeter data show interior deposits that locally (1)
reach 4-km in height, (2) rise above sections of plateau, and (3) in the
case of

Hebes, have the distinctive tuya form. Their morphologies include local
resistant caps [12], ridged forms, and possible deltas. Based on the
dimensions, morphologies, and associated catastrophic floods and other
geologic events (glacial, tectonic, and mass flows) we support the
suggestion that the interior deposits are hyaloclastic ridges and
tuyas.” Page 15 Volcano/Ice Interaction Workshop August 13-15, 2000
ReykjavÍk, Iceland available online at

http://astrogeology.usgs.gov/Projects/VolcanoIceWorkshop/abstract_volume_rev5.pdf

[17] <#_ftnref17> “Valles Marineris shows a strong negative anomaly
congruent with the topography (Fig 6). The rift axis anomaly is the
largest negative

gravity feature on Mars and is due mostly to the mass deficit associated
with the chasm (29), which has a depth of 11 km below the surrounding

terrain at its lowest point (12). The canyons are flanked by gravity
highs but the canyon system lacks a negative anomaly, broader than

the rift, that is associated with upwelling of hot mantle material
beneath active rifts on Earth (30). The deviation of the canyon from
isostatic compensation is consistent with its formation subsequent to
Argyre and Hellas (31) and suggests that the martian lithosphere has not
yet adjusted to its presence.” David E. Smith et al “The Gravity Field
of Mars: Results from Mars Global Surveyor” available online at

http://ltpwww.gsfc.nasa.gov/tharsis/smith.mgs.grav.pdf

[18] <#_ftnref18> Fig 6 David E. Smith et al “The Gravity Field of
Mars:Results from Mars Global Surveyor” available online at
http://ltpwww.gsfc.nasa.gov/tharsis/smith.mgs.grav.pdf

[19] <#_ftnref19>  K. F. Sprenke and L. L. Baker “POLAR WANDERING ON
MARS?” Lunar and Planetary Science XXXI 1930.pdf
<http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1930.pdf>

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1930.pdf

[20] <#_ftnref20> Fig 1a David E. Smith et al “The Gravity Field of
Mars: Results from Mars Global Surveyor” available online at

http://ltpwww.gsfc.nasa.gov/tharsis/smith.mgs.grav.pdf

[21] <#_ftnref21>http://www.harmakhis.org/history/1.jpg
<http://www.harmakhis.org/history/3.jpg>

[22] <#_ftnref22> “Clusters of small cones on the lava plains of Mars
have caught the attention of planetary geologists for years for a simple
and compelling reason: ground ice. These cones look like volcanic
rootless cones found on Earth where hot lava flows over wet surfaces
such as marshes, shallow lakes or shallow aquifers. Steam explosions
fragment the lava into small pieces that fall into cone-shaped debris
piles. Peter Lanagan, Alfred McEwen, Laszlo Keszthelyi (University of
Arizona), and Thorvaldur Thordarson (University of Hawaii) recently
identified groups of cones in the equatorial region of Mars using new
high-resolution Mars Orbiter Camera (MOC) images. They report that the
Martian cones have the same appearance, size, and geologic setting as
rootless cones found in Iceland. If the Martian and terrestrial cones
formed in the same way, then the Martian cones mark places where ground
ice or groundwater existed at the time the lavas surged across the
surface, estimated to be less than 10 million years ago, and where
ground ice may still be today.” Linda M.V. Martel
<http://www.higp.hawaii.edu/~linda> “If Lava Mingled with Ground Ice on
Mars” PSR Discoveries [6/26/01] available online
athttp://www.psrd.hawaii.edu/June01/lavaIceMars.html

[23] <#_ftnref23> “The southern rim of the Isidis Basin has been
strongly modified by erosional processes, including weathering, mass
wasting, fluvial incision, and transport and deposition of sediment.
Most of this erosion occurred during the Noachian, but a late stage
of fluvial incision probably extended into the Hesperian.” J.M.
Moore (NASA Ames), A.D. Howard (UVa), P.M. Schenk (LPI) “[48.08]
Geomorphic Analysis of the Isidis Region: Implications for Noachian
Processes and Environments” DPS 2001 meeting, November 2001
Session 48. Mars Surface available online
athttp://www.aas.org/publications/baas/v33n3/dps2001/221.htm

[24] <#_ftnref24> http://www.harmakhis.org/history/2.jpg

[25] <#_ftnref25> H. V. Frey, S. E. H. Sakimoto, and J. H. Roark “MOLA
TOPOGRAPHY AND THE ISIDIS BASIN: CONSTRAINTS ON BASIN CENTER AND RING
DIAMETERS” LPSC98 available online at

http://mars.jpl.nasa.gov/mgs/sci/lpsc98/1631.pdf

[26] <#_ftnref26> Figure 1a

[27] <#_ftnref27> “3) a site at ~5°S and 264°W just south of the Isidis
rim that is heavily dissected by channels. These regions were optimally
imaged by Viking for the generation of DTMs, lie within the Mars 2001
landing constraints, and are potential locations for fluvial or
lacustrine deposits. Our initial analysis of the later sites indicates
that fluvial erosion for large solitary channels probably took the form
of sapping, whereas denser networks of small channels may have formed at
least in part from runoff, such as from surface ice-melt. Both sites
show that channeling took place during a period in which fairly large
craters will still forming. The tectonic fabric appears to largely
predate the channeling. Aeolian deposition largely post dates the
channeling.”

J. M. Moore (NASA Ames), A. D. Howard (U. Va.), P. M. Schenk (LPI)
“[43.04] The Topography and Basin Deposits of the Equatorial Highlands:
A MGS–Viking Synergistic Study” 31st Annual Meeting of the DPS, October 1999
Session 43. Mars Surface: Structure available online at

http://www.aas.org/publications/baas/v31n4/dps99/98.htm

[28] <#_ftnref28> J.A.Iluhina and J.F.Rodionova “AUTOMATED MAKING THE
MAP OF ISIDIS’S BASIN” Microsymposium 36, MS037, 2002 available online at

http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/037_Iluhina_Rodionova.pdf

[29] <#_ftnref29> http://www.harmakhis.org/history/2.jpg

[30] <#_ftnref30>“Isidis is generally very flat with low average
slope values calculated from MOLA data.” The Natural History Museum
“Missions to Mars” available online at
http://www.nhm.ac.uk/mineralogy/mars/Marshtml/2missions.html

[31] <#_ftnref31> http://www.space4case.com/mars/mars7/mars143.html

[32] <#_ftnref32> http://www.space4case.com/mars/mars7/mars142.html

[33] <#_ftnref33> “Beagle 2 has as its focus the goal of establishing
whether evidence for life existed in the past on Mars at the Isidis
Planitia site or at least establishing if the conditions were ever
suitable.” Page 4 J. D. Farmer “Exploring for Martian Life: Recent
Results and Future Opportunities” Astrobiology Volume 1 Number 3 [2001]
available online at
http://216.239.57.104/search?q=cache:XenIThQGrU8J:cips.berkeley.edu/events/discussion_group_2003_spring/farmer_astrobiology_space_missions.pdf+farmer_astrobiology_space_missions.pdf&hl=en&ie=UTF-8

[34] <#_ftnref34>First image Ames Research Centre available online at
http://amesnews.arc.nasa.gov/releases/2002/02images/mars/mars.html

[35] <#_ftnref35> "When the river valleys on Mars were confirmed in the
1970s, many scientists believed there once was an Earth-like period with
warmth, rivers and oceans," said Owen Toon, a professor at the
University of Colorado and a coauthor of the Science paper. "What
sparked our interest was that the large craters and river valleys
appeared to be about the same age." Another piece of evidence arguing
against a condition warm, wet period on Mars are images of river
channels without any sign of tributaries flowing into the main channel.
"We definitely see river valleys but not tributaries, indicating the
rivers were not as mature as those on Earth," said Toon. Jeff Foust “New
research explores past, present water on Mars” Spaceflight Now December
5^th 2002 available online at http://spaceflightnow.com/news/n0212/05mars/

[36] <#_ftnref36> Nancy Ambrosiano “Los Alamos releases new maps of Mars
water” Los Alamos National Laboratory [2003] available online at

http://www.lanl.gov/orgs/pa/News/cover_epi.jpg

[37] <#_ftnref37> M. L. Litvak “DISTRIBUTION OF CHEMICALLY BOUND WATER
IN SURFACE LAYER OF MARS BASED ON DATA ACQUIRED BY HIGH ENERGY NEUTRON
SPECTROMETER, MARS ODYSSEY” Microsymposium 36, MS062, 2002

http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/062_Litvak_etal.pdf

[38] <#_ftnref38>“The Solis Planum region of Mars is a high-elevation
volcanic plain which lies south of the Valles Marineris canyon system
and east of the Tharsis volcanic complex. In the 1970s, Earth-based
photometric observations of dust storms in this region suggested that
H2O condensate clouds were produced from a volatile-rich source
located in Solis Lacus, the low-albedo area of Solis Planum. High
reflectivity radar returns of the Solis region in the 1980s were
interpreted as resulting from a seasonal freeze-thaw cycle of H2O in
the upper centimeter of regolith. These observations led to
speculation that a water-rich "oasis" exists near the surface in Solis
Planum. However, Viking Mars Atmospheric Water Detector (MAWD)
measurements did not find significant differences in water vapor
column abundances between Solis Planum and elsewhere, and the oasis
hypothesis faded from debate by the end of the 1980s. Recent advances
in the understanding of the geologic evolution of this region combined
with new high-resolution observations of geologic features suggesting
an extensive volatile reservoir underlying Solis Planum have led our
group to revisit the oasis hypothesis. Ejecta formation simulation
codes are being used to estimate the amounts of volatiles in the
substrate and measurements from the Mars Odyssey instruments should
help to confirm if H2O is concentrated in this region.” Nadine Barlow
“SOLIS PLANUM, MARS: THE "OASIS HYPOTHESIS" REVISITED “2001-2002
Colloquium Series NAU Liberal Arts (Bldg 18, Rm 135), Thursday, 24
January 2002 available online at 
http://www.phy.nau.edu/EVENTS/colloquium/speakers0102/barlow.html

[39] <#_ftnref39>“ Koroshetz and Barlow [12], using Viking Orbiter
imagery, found smaller onset diameters for SL morphology craters in the
Solis Planum region south of Valles Marineris (20?S-30?S 50?W-90?W), one
of the same

regions where [6] found a higher concentration of ML morphologies.
Koroshetz and Barlow propose that the uplift of the Tharsis Bulge,
directly west of this region, caused the water table in this area to
tilt and the water flowed into a topographic depression south of

Valles Marineris.”  N. G. Barlow “SUBSURFACE VOLATILE RESERVOIRS: CLUES
FROM MARTIAN IMPACT CRATER MORPHOLOGIES” Fifth Conference 1999
http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6082.pdf

[40] <#_ftnref40> “A group of scientists claims to have found evidence
of liquid water under the surface of Mars. The team, led by Nadine
Barlow of the University of Central Florida’s Robinson Observatory
<http://phys.physics.ucf.edu/cfas/Observatory.html>, believes the
reservoir lies relatively close to the surface, at a depth of roughly
110 meters (360 feet).” Ames Research Centre “Mars Watering Hole Found,
Scientists Say” available online at

http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=1009

[41] <#_ftnref41> “Our current study suggests that the ice-rich layer
producing the SL morphology lies closer to the surface (<300 to 500 m)
in the Solis Planum region than elsewhere in the equatorial region
(~520-572 m) and that an underlying liquid reservoir, which produces the
ML morphologies, has been present since the region formed in the
Hesperian.” N. G. Barlow, C. B. Perez (U. Central Fl.), J. Koroshetz (U.
Fl.) “[39.06] A Volatile-Rich Reservoir South of Valles Marineris, Mars”
31st Annual Meeting of the DPS, October 1999 Session 39. Mars Surface:
Evidence of Change available online at
http://www.aas.org/publications/baas/v31n4/dps99/40.htm

[42] <#_ftnref42> “We propose that the uplift of the Tharsis Bulge to
the west of this region warped the area and tilted a pre-existing
groundwater table. The tilting of the groundwater table caused the
volatiles to accumulate in the slight depression where today the smaller
onset diameters and abundance of ML morphologies are found.”  Ibid.

[43] <#_ftnref43> “8.4. Glacial Features

Another possible explanation of the circumferential features is

that they are related to morainal/ice-margin features. A glacial

explanation has been advanced for the formation of thumbprint

terrain [Lucchitta, 1981; Rossbacher, 1985; Lucchitta et al., 1987;

Scott and Underwood, 1991; Scott et al., 1992; Kargel and Strom,

1992; Kargel et al., 1995]. As shown in Figure 10, there are areas of

thumbprint terrain that are located in the middle of the zone of

circumferential features in southern Utopia. On the basis of the

morphology and distribution of thumbprint terrain and other structures,

several workers have suggested the former presence of large

ice sheets in the northern hemisphere of Mars [Lucchitta et al.,

1986; Chapman, 1994; Kargel et al., 1995]. The lack of associated

glacial flow features such as drumlins in the northern plains seems

inconsistent with widespread glacial activity. Drumlins are streamlined

mounds of glacial till that have elongated teardrop shapes in

plan view [Benn and Evans, 1998]. The absence of drumlins does

not rule out a glacial explanation, for a glacial body in the northern

hemisphere may have been cold-based for much of its evolution

[e.g., Kargel et al., 1995]. However, the lack of drumlins highlights

the general lack of features related to mass ice movement and scour

in the interior of the Northern Plains. In addition, because ice

experiences a drop in plasticity with decreasing temperature [Glen,

1955; Goldsby et al., 2001], the current temperature regime on Mars

would tend to inhibit glacial flow. This does not exclude the
possibility of glacial activity at periods of high obliquity or more

temperate paleoclimatic conditions but highlights the need for a

greater understanding of ice deformation mechanisms [Goldsby et

al., 2001] under possible Martian paleoclimates before the viability

of a glacial explanation can be verified.” Bradley J. Thomson and James
W. Head III “Utopia Basin, Mars: Characterization of topography and
morphology and assessment of the origin and evolution of basin internal
structure” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. 0, PAGES 1–22,
MONTH 2001 available online at

http://www.planetary.brown.edu/planetary/documents/2396.pdf

[44] <#_ftnref44> “A study of martian impact craters with fluidized
ejecta morphologies has revealed that the area south of the Valles
Marineris canyon system may contain a large near-surface volatile
reservoir.” N. G. Barlow, C. B. Perez (U. Central Fl.), J. Koroshetz
(U. Fl.) “[39.06] A Volatile-Rich Reservoir South of Valles
Marineris, Mars” 31st Annual Meeting of the DPS, October 1999
Session 39. Mars Surface: Evidence of Change available online at
http://www.aas.org/publications/baas/v31n4/dps99/40.htm

[45] <#_ftnref45> “Evidence for a large ground water reservoir -- capped
by a relatively shallow layer of ice -- exists within the Mars'
Solis/Thaumasia Planum region, says a team of scientists. The site is
south of the huge Martian canyon system, Valles Marineris.” Leonard
David
<http://space.com/scienceastronomy/solarsystem/ldavid at hq.space.com>
“Mars Watering Hole Found, Scientists Say” Space.com posted: 03:00 pm ET
13 August 2001

http://space.com/scienceastronomy/solarsystem/mars_ice_010813.html

[46] <#_ftnref46>“ We propose that the strain from Syria Planum was
transferred along proto-Valles Marineris forming a sinistral
transtensional zone which provided tectonic control for later valles
formation. At the east end of Valles Marineris, the Coprates Rise is a
lithospheric buckle with a thrust fault along the eastern edge. We also
interpret the southern edge of the Thaumasia Highlands as the surface
exposure of a thrust fault. The compressional structures of the Coprates
Rise appear to extend into the Thaumasia Highlands. The thrust faults
likely cut deep into the crust and may represent the décollment for
later wrinkle ridge faulting in Sinai and Solis Planum. In this
hypothesis, Claritas Fossae represents a dextral transpressional zone
and acts as a boundary between the eastern and western halves of the
south-Tharsis ridge belt identified by Schultz and Tanaka (1994, JGR 99,
p. 8371), which includes the Coprates Rise, Thaumasia Highlands, and
ridges in Daedalia Planum. Compression in Daedalia Planum likely
resulted from the same forces affecting the Thaumasia Plateau in the
Noachian, but was arrested at an earlier stage of development, perhaps
due to the buttressing effect of early Tharsis Montes construction.”
WEBB, Benjamin M. <mailto:Benjamin_Webb at Brown.edu> “NOACHIAN TECTONICS
OF SYRIA PLANUM AND THE THAUMASIA PLATEAU” Paper No. 132-0 [2001]
available online at
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_28019.htm

[47] <#_ftnref47> “Summary: It is argued that Syria, Sinai and Solis

Plana were generated by the volcanic activity associated with a mantle
plume. They formed a large lithospheric root which was removed in a
convective downwelling initiating a buoyant rebound of the region,
followed by later subsidence when this uplift could no longer be
sustained. The sequence of faulting within the region [6] is consistent
with this scenario.”  Evelyn D. Scott “SUB-LITHOSPHERIC ‘SUBDUCTION’ ON
MARS: CONVECTIVE REMOVAL OF A LITHOSPHERIC ROOT. III: SYRIA PLANUM
REGION” Lunar and Planetary Science XXXI 1331.pdf
http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1331.pdf

[48] <#_ftnref48> “This hypothesis easily combines the various
hypotheses that Valles

Marineris formed either as a thermal response to events in the Martian
mantle or as a tectonic response to the loading of Tharsis. If it is
argued that there is an asthenospheric upwelling below the Plana, then
the Wernicke 'Simple Shear' model can be invoked to explain the opening
of Valles Marineris. In this model the upwelling is lateral to the site
of the rifting, whereas McKenzie's 'Pure Shear' model would locate the
site of rifting immediately above the mantle decompression. The fact
that the fissure system of Noctis Labyrinthus has not evolved to the
same extent as that of Valles Marineris could be because it is not as
close to the thermal influence of the upwelling or because it has formed
simply as a response to the isostatic realignment and was not influenced
to as great an extent by the growth of the Tharsis volcanic shields.” Ibid.

[49] <#_ftnref49> http://www.space4case.com/mars/mars6/mars125.html

[50] <#_ftnref50> “The new topographic data illuminate a long-standing
debate over the dominant contributors to the high elevations of the
Tharsis region. A prominent ridge (containing Claritas Fossae; Fig. 2)
extends southward from the region of the Tharsis Montes, and then curves
northeastward in a “scorpion tail” pattern. This arcuate ridge bounds
Solis Planum, a plateau within the southern rise. The ridge contains an
abundance of heavily cratered Noachian material that has presumably
escaped resurfacing by younger Tharsis volcanic flows because of its
high elevation. It has been suggested (25) that the termination of the
ridge structure could have formed by lithospheric buckling, as could, by
analogy, other ridge structures in the south Tharsis region. The
southern rise (southward of ;35°S) also contains exposures of heavily
cratered Noachian units. These elevated ancient terrains are consistent
with the view that the broad expanse of the southern rise (elevations
.;3 km; see Fig. 2) formed at least in part by structural uplift (26).
David E. Smith “The Global Topography of Mars and Implications for
Surface Evolution” www.sciencemag.org SCIENCE VOL 284 28 MAY 1999
available online at

http://www.ciw.edu/library/solomon/sci_284_1495.pdf

[51] <#_ftnref51> “Figure 3 shows crater counts from a younger area,
Solis Planum, where there has not been as much time for infilling, and
the larger-crater population is more completely preserved, falling
closer to the lunar mare reference line (dashed).” William K. Hartmann
“MARTIAN CRATER POPULATIONS AND OBLITERATION RATES: FIRST RESULTS FROM
MARS GLOBAL SURVEYOR” 1998, LUNAR AND PLANETARY SCIENCE CONFERENCE 29
(HOUSTON) available online at

http://www.psi.edu/projects/mgs/lpsc.html

[52] <#_ftnref52> MSSS “Wide Angle View of Arsia Mons Volcano” MGS MOC
Release No. MOC2-179, 27 September 1999
http://mars.jpl.nasa.gov/mgs/msss/camera/images/9_27_99_arsia/

[53] <#_ftnref53> Calvin J. Hamilton “Arsia Mons” 1997 available online at

http://www.star.ucl.ac.uk/~apod/solarsys/cap/mars/arsia.htm

[54] <#_ftnref54> “Surface environmental conditions on Mars are
presently extremely cold and hyperarid, most equivalent to polar deserts
on Earth. Coupling newly acquired Mars MOLA and MOC data with
field-based observations regarding the flow, surface morphology, and
depositional history of polar glaciers in Antarctica, we show that the
multiple facies of an extensive fan-shaped deposit on the western flanks
of Arsia Mons, Tharsis Rise are consistent with deposition from
cold-based mountain glaciers. An outer ridged facies that consists of
multiple laterally extensive, arcuate and parallel ridges, resting
without disturbance on both well-preserved lava flows and an impact
crater, is interpreted as drop moraines formed at the margin of an
ablating and predominantly

receding cold-based glacier. Inward of the ridges lies a knobby facies
that consists of irregular and closely spaced equidimensional knobs,
each up to several kilometers in diameter; this facies is interpreted as
a sublimation till derived from in situ downwasting of ash-rich glacier
ice. A third facies comprising distinctive convex outward lobes with
concentric parallel ridges and aspect ratios elongated downslope likely
represents rock-glacier deposits, some of which may still be underlain
by a core of glacier ice. Taken together, these surficial deposits show
that the western flank of Arsia Mons was occupied by an extensive
mountain glacial system accumulating on, and emerging from, the upper
slopes of the volcano (above ˜7000 m) and spreading downslope to form a
piedmont-like fan. Similar deposits exist on the other Tharsis Montes,
suggesting at least one phase of late Hesperian aged glaciation in the
equatorial Tharsis region.” J. W. Head , D. R. Marchant “COLD-BASED
MOUNTAIN GLACIERS ON MARS: WESTERN ARSIA MONS” Geophysical Research
Abstracts, Vol. 5, 02770, 2003

c European Geophysical Society 2003 available online at

http://www.cosis.net/abstracts/EAE03/02770/EAE03-J-02770.pdf

[55] <#_ftnref55> “Using new MGS data and Earth analogs appropriate for
Mars, we explored the hypothesis that the deposit is the remnant of a
mountain glacier formed on the western flank of Arsia Mons (e.g., [1]).
Conditions during the recent geological history of Mars suggest that
glacial ice should commonly be below the pressure melting point, and
thus analogous to polar glaciers, which are frozen to underlying beds
(cold-based), and move by internal deformation, producing no record of
basal scour or extensive meltwater features. Glaciers in the Antarctic

Dry Valleys may be most appropriate terrestrial analogs, and we find
many similarities between them and the western Arsia fan-shaped
deposits. We interpret the outer parallel ridge zone to be distal

dump moraines formed from the lateral retreat of a coldbased

glacier, and the hummocky facies to be proximal hummocky moraines
resulting from the sublimation, decay and downwasting of the ice sheet
(a sublimation till). The arcuate structures in the proximal zone are
interpreted to be rock glaciers, formed by lobate flow deformation of
debris-covered ice surfaces; some rock glaciers may still be ice-cored.
We find little evidence for melting features in association with the
deposit, and thus conclude that it was predominantly cold-based
throughout its history. In summary, we find abundant evidence to support
the interpretation that the fanshaped western Arsia Mons deposit was
formed by a cold-based mountain glacier. Similar deposits are seen

on Pavonis and Ascraeus Montes.” James W. Head and David R. Marchant
“MOUNTAIN GLACIERS ON MARS?: WESTERN ARSIA MONS FAN-SHAPED DEPOSIT
SMOOTH FACIES AS ROCK GLACIERS:” Microsymposium 36, MS103, 2002

http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/103_Head_Marchant.pdf

[56] <#_ftnref56> “Characterization: The basic units comprising Arsia
Mons consist of lava flow members of the Tharsis Montes Formation [2;
see also 3], and the oldest flows are Late Hesperian in age, and younger
units span the Amazonian. Scott and Zimbelman [1] show that during the
Amazonian, three lava flow members of the Tharsis Montes Formation and
the three facies of the fan-shaped deposit were emplaced. The ridged
facies of the fan deposit clearly overlies Member 5 and is thus
considered to be Late Amazonian in age.” James W. Head and David R.
Marchant “MOUNTAIN GLACIERS ON MARS? CHARACTERIZATION OF WESTERN ARSIA
MONS FANSHAPED DEPOSITS USING MGS DATA:”  Microsymposium 36, MS105, 2002

http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/105_Head_Marchant.pdf

[57] <#_ftnref57> “Introduction: Prominent magnetic anomalies are absent
over the major volcanic edifices of Mars. Apparently the martian global
magnetic field ceased to exist long before the volcanism north of the
dichotomy

occurred [1]. However, Arsia Mons, the southernmost of the great shield
volcanoes of Mars, is located adjacent to a large regional magnetic
anomaly (Fig.1). This raises the question of whether the Arsia Mons
lavas might have acquired a magnetization induced from the much older
remnant magnetization in the adjacent crust. This magnetization, induced
by local fields associated with magnetized regions of the crust, would
have occurred in spite of the absence of a global field at the time of
emplacement.” And see Figure 1 K.F. Sprenke and L.L. Baker
“Magnetization of Arsia Mons, Mars” Lunar and Planetary Science XXXIII
(2002) 1070.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1070.pdf

[58] <#_ftnref58> “Recently, it was proposed, on the basis of a
morphological interpretation of Viking Orbiter images, that a thick ice
sheet covers the Arsia Mons volcano in the Tharsis province on Mars,
i.e. almost on the equator (Geology, March 1999, v. 27; no. 3; p.
231-234).” This conclusion is reached by examining deep canyons that cut
into the fan areas of Arsia Mons and almost reach into the caldera area.
These canyons are interconnected to circular vent-like structures that
are interpreted as openings where ice has been melted above eruptive
volcanic sites.

These vent-like openings lack a collar of ash normally associated with
eruptive vents. The close association of a fissure swarm, large scale
canyons, numerous vent-like structures and a broad fan area concur with
a genetic relationship between these features.” Johann Helgason “Does
Mars Hide Vast Water Deposits” MARSDAILY.COM SPECIAL REPORT
<http://www.marsdaily.com/water.html> Reykjavik - June 10, 2000
available online athttp://www.spacedaily.com/news/mars-water-00b.html

[59] <#_ftnref59>“The Argyre Basin”
http://ltpwww.gsfc.nasa.gov/tharsis/argyre_insight.html

[60] <#_ftnref60> See Figure 1 K. F. Sprenke and L. L. Baker “POLAR
WANDERING ON MARS?” Lunar and Planetary Science XXXI 1930.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1930.pdf

[61] <#_ftnref61> http://www.harmakhis.org/history/3.jpg

[62] <#_ftnref62> http://www.harmakhis.org/history/4.jpg

[63] <#_ftnref63> http://www.harmakhis.org/history/shockwave.jpg

[64] <#_ftnref64> http://www.space4case.com/mars/mars5/mars110.html

[65] <#_ftnref65> “Based on volume estimates of [13] which are based on
a 3 km thick ice cap that covered the entire area of the Dorsa Argentea
Formation, ~6.63 x 106 km3 of water could have been released. However,
taking into account that the ice thickness very likely decreased toward
the margins of the ice cap, that the ice cap contained up to 50%
sediments, that not all of the melt water ended in the Argyre basin,
that large amounts of ice never underwent melting but sublimed, and that
large amounts of water are still stored in the pore space of the Dorsa
Argentea Formation, we calculated that there is probably not enough
water to completely fill the Argyre basin due to meltback of a Hesperian
polar cap. We argue that partly filling the Argyre basin with water
derived from polar cap meltback is more likely and is also consistent
with Hesperian channels cutting far down into the basin.” H. Hiesinger,
J.W. Head III

“GEOLOGY OF THE ARGYRE BASIN, MARS: NEW INSIGHTS FROM MOLA AND MOC”
Lunar and Planetary Science XXXII (2001) 1799.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1799.pdf

[66] <#_ftnref66>“Catastrophic flooding out of Argyre: Uzboi Valles is a
relatively large, Noachian outflow channel that cuts the northern rim of
Argyre (Nereidum Montes) and drained northward toward Holden Crater,
into Holden Basin [7]. Without good topography, however, Uzboi Valles is
somewhat confusing. With both ends obliterated by large impact craters
and the channel floor exhibiting few streamlined forms, it isn’t even
obvious which way the channel flowed. However, even the gridded MOLA
topography clearly shows Uzboi probably linked the Argyre interior with
Holden Basin and Ladon Valles prior to formation of the large craters
(Fig. 1). Next in the system is Holden Basin [7], into which Uzboi
Vallis flow continued prior to formation of Holden Crater [2]. The
northeast rim of Holden Basin is “gone” even though this basin
superposes Ladon Basin. Instead, a broad “ramp” was identified in Viking
Orbiter stereo pairs [2]. Ladon and Arda Valles converge on this ramp
and drain into the interior of Ladon Basin. Parker [2] inferred that the
rim of Holden Basin failed catastrophically during flooding from Argyre
to produce this ramp, which drained a temporary lake that had formed in
Holden Basin. Continued flooding from Uzboi Vallis favored Ladon Valles’
course, so Arda Valles was quickly abandoned. Channel morphology
disappears just inside the inner rim of Ladon Basin, but resumes on the
basin’s northeast side, at Margaritifer Valles [8].”

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/2033.pdf

Parker et al., [2000], LPSC XXXI, 2033.pdf

[67] <#_ftnref67> “Most highland basins show evidence of some
communication between higher basins and adjacent, lower basins. The high
plateau of Solis Planum exhibits surface drainage eastward through Her
Desher Vallis–Nirgal Vallis into the upper parts of the Chryse Basin [1]
as well as discharge westward into Amazonis as proposed by Dohm et al. [10].

Likewise, the Argyre basin overflowed northward through Nirgal–Uzboi
Valles [11] into the Ladon basin and Margaritifer Basin [12] and
eventually into Chryse Planita. The various interconnected lowlands

of Icaria Province probably spilled over the southern rim into Argyre
[1] providing a continuous pathway from the southern polar region to the
northern ocean.” R.A. De Hon “MARTIAN SEDIMENTARY BASINS AND REGIONAL
WATERSHEDS” Lunar and Planetary Science XXXIII (2002) 1915.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1915.pdf

[68] <#_ftnref68> See Figure 1 Lionel Wilson and James W. Head III
“Tharsis-radial graben systems as the surface manifestation of
plume-related dike intrusion complexes: Models and implications” JOURNAL
OF GEOPHYSICAL RESEARCH, VOL. 107, NO. E8, 10.1029/2001JE001593, 2002

http://www.planetary.brown.edu/planetary/documents/2584.pdf

[69] <#_ftnref69> “A system of gigantic ancient valleys -- some as much
as 200 kilometers wide -- lies partly buried under a veneer of volcanic
lava flows, ash fall and wind-blown dust in Mars' western hemisphere.
New observations made with Mars Orbiter Laser Altimeter on the Mars
Global Surveyor spacecraft reveal northwestern slope valleys (NSVs)
northwest of the huge martian volcano, Arsia Mons, and south of Amazonis
Planitia, site of a postulated ocean.” Lori Stiles “Scientists Find
Largest Flood Channels in the Solar System” University of Arizona
uanews.org  [2001] available online at

http://uanews.opi.arizona.edu/cgi-bin/WebObjects/UANews.woa/wa/SRStoryDetails?ArticleID=3995

[70] <#_ftnref70> http://www.lanl.gov/orgs/pa/News/cover_epi.jpg

[71] <#_ftnref71> http://www.harmakhis.org/history/5.jpg

[72] <#_ftnref72> http://www.harmakhis.org/history/6.jpg

[73] <#_ftnref73> “Especially prominent are the Nilae Fossae around the
Isidis basin, but less distinct concentric graben and scarps are visible
around the Argyre and Hellas basins.” BY THE VIKING ORBITER IMAGING
TEAM  “Deformational features” NASA SP-441

http://history.nasa.gov/SP-441/ch6.htm

[74] <#_ftnref74> http://www.harmakhis.org/history/7.jpg

[75] <#_ftnref75> “Introduction: The Margaritifer Sinus region of Mars
preserves some of the highest valley network densities on the planet
[1-4]. Two large northwest draining valley systems, Samara and
Parana-Loire Valles, whose associated basins cover an area exceeding
540,000 km2, dominate regional drainage. These valley systems converge
on Margaritifer Basin, a confluence plain shared with the
Uzboi-Holden-Ladon-Margaritifer Valles meso-outflow system (UHLM) that
drains northward from Argyre. Detailed geologic and morphometric mapping
of the Samara and Parana-Loire valley systems confirms the timing of
incisement and permits evaluation of possible mechanisms for valley
evolution [2, 5-8].” J. A. Grant “Valley Evolution in Margaritifer
Sinus, Mars” Available online at

http://www.nasm.si.edu/ceps/research/grant/grant_marg2.pdf

[76] <#_ftnref76> “features in Margaritifer Sinus. Four resurfacing
events that deposited materials interpreted to be of mostly volcanic
origin on the basis of wrinkle ridges and occasionally lobate morphology
followed formation of these basins. The first three resurfacing events were

widespread and ended before evolution of the preserved valleys; the
first two occurred during early Noachian heavy bombardment [11] and the
second ended at an N5 age of 1400 (number of craters >5 km in diameter

per 1,000,000 km2). By contrast, the third resurfacing event began
during the middle Noachian (N5 of 500) and ceased during the late
Noachian (N5 of 300) coincident with waning highland volcanism [11].
Formation of Samara and Parana-Loire Valles, the UHLM system, infilling
of associated depositional sinks (e.g., Parana Basin at 12.50W, 22.50S),
and initial collapse of Margaritifer Chaos all occurred from the late
Noachian (N5 of 300) into the early Hesperian (N5 of 150). The last,
more localized resurfacing event lasted into the early and middle
Hesperian (N5 ages 200 to 70) and emplaced materials that embay valleys.
Nearly all area surfaces have been subsequently modified to varying

degree by eolian activity.” Ibid. available online at

http://www.nasm.si.edu/ceps/research/grant/grant_marg2.pdf

[77] <#_ftnref77> “Model for Valley Evolution: A model for valley
formation consistent with these results involves mostly localized
ground-water discharge enabled by surface fed recharge. In this model,
precipitation (rain or snow) would be largely relegated to subsurface
entry by high

surface-infiltration capacities. Discharge at exposed relief would be
controlled by occurrence of layers/ aquitards. Valley evolution would
have continued until draw-down of the water table following cessation

of precipitation, thereby resulting in a strong sapping overprint.

Martian valley formation by this process may best explain observed
morphometry. For example, the basin wide distribution of valleys (Fig.
1), low drainage density and ruggedness numbers, degree of integration,

and sediment volume in along-valley sinks may be difficult to
accommodate in a hypothesis involving ground-water discharge in the
absence of surface recharge. With surface-fed recharge, valley
distribution would be controlled mostly by the occurrence of layers/

aquitards.” Ibid. Available online at

http://www.nasm.si.edu/ceps/research/grant/grant_marg2.pdf

[78] <#_ftnref78> “The crustal structure accounts for the elevation of
the Martian northern lowlands, which controlled the northward flow of
water early in Martian history, producing a network of valleys and
outflow channels. The new gravity-field data suggest that the transport
of water continued far into the northern plains. The gravity shows
features interpreted as channels buried beneath the northern lowlands
emanating from Valles Marineris and the Chryse and Kasei Valles outflow
regions.” Goddard Space Flight Centre “View inside Mars reveals rapid
cooling and buried channels” March 9 2000 available online at*
* http://www.gsfc.nasa.gov/topstory/20000309mars.html

[79] <#_ftnref79> “Geologic mapping in Margaritifer Sinus, Mars, defines
a complex history of water transport, storage, and release that began in
the late Noachian and persisted into at least the mid-Hesperian.
Collection, transport, and discharge of the water from widely dispersed
surfaces were accomplished by systems of differing character flanking
opposite sides of the Chryse Trough. Drainage on the western side of the
trough was accommodated by the segmented Uzboi-Ladon-Margaritifer
mesoscale outflow system that heads in Argyre basin, drains
approximately 9% of the Martian surface, and alternately incises and
fills as it crosses ancient multi-ringed impact basins.” John A. Grant
“DRAINAGE EVOLUTION IN MARGARITIFER SINUS, MARS” Paper No. 132-0 GSA
Annual Meeting, November 5-8, 2001 Boston, Massachusetts
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_27669.htm

[80] <#_ftnref80> Dave Williams “Parana Valles drainage system in
Margaritifer Sinus, Mars” available online at

http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vo1_084a47.html

[81] <#_ftnref81> “Using high-resolution topographic data from the Mars
Orbiter laser

altimeter (MOLA) instrument on the Mars Global Surveyor mission

(Smith et al., 1999), we have gathered evidence for a major fluvial

resurfacing event in the Martian highlands. We completed detailed
geomorphic mapping for the Margaritifer Sinus region (08–308S, 08–

308W), where resurfacing appears most evident. In addition, evidence

from adjacent areas suggests that this was not a localized event, but

one that affected at least 1 3 107 km2 (an area equivalent to the
European continent) of the cratered uplands. The topographic information

allows for the first time a separation of younger, low-standing
fluvially reworked terrains from older, high-standing erosional
remnants. The newly acquired MOLA data also allow the volume of eroded
material to be sensibly determined and minimum erosion rates to be
estimated. The erosional episode was limited in time to no more than
several hundred million years, and occurred ca. 4 Ga. The scale of the
processes involved strongly suggests, but does not demonstrate uniquely,

that precipitation must have played a major role in landscape denudation

in this region of Mars.” Brian M. Hynek and Roger J. Phillips “Evidence
for extensive denudation of the Martian highlands” available online at

http://ltpwww.gsfc.nasa.gov/tharsis/hynek.erosion.pdf

[82] <#_ftnref82> Formation processes of valley networks are still
controversial; the

debate is largely focused on the relative roles of surface runoff and

groundwater processes. In the mapped region, the morphology of the

valleys and associated networks (v-shaped profile, sinuous, high
density, and high valley order) and the observation that numerous
valleys originate near the tops of crater rims or hilltops (Fig. 3)
indicate that precipitation and surface runoff may have played a major
role in their formation. Some valleys show morphologies more consistent
with a groundwater-sapping origin (u-shaped profile, low density and
order, and alcove-like terminations), suggesting that subsurface water
was also important. Therefore, both precipitation and groundwater
certainly contributed to degradation in the Margaritifer Sinus region,
but the relative importance of each erosion mechanism is unclear. These
results are consistent with previous work completed on the south-central
part of our study area (Grant, 2000).” Ibid. available online at

http://ltpwww.gsfc.nasa.gov/tharsis/hynek.erosion.pdf

[83] <#_ftnref83> “There is evidence for a large paleolake in the region
(Parana basin;

22.58S, 12.58W, area ;33 000 km2) (Goldspiel and Squyres, 1991). The

depression contains hummocky interior deposits with interspersed smooth
terrain (Ni) that were emplaced contemporaneously with the extensive
denudation and valley network formation. A large number of valley
systems terminating at the proposed shoreline of Parana basin are
believed to have been sources for the paleolake (Goldspiel and

Squyres, 1991). The unit HNl contains a hematite spectral signature

and is interpreted to be sedimentary layers deposited from large-scale

water interactions (Christensen et al., 2000).” Ibid. Available online
at http://ltpwww.gsfc.nasa.gov/tharsis/hynek.erosion.pdf

[84] <#_ftnref84> “J.A. Grant examined the valley networks in the
Margaritifer Sinus region, the area on Mars where they are most
concentrated, and concluded that they were indeed carved by "sapping"
(tunneling by underground water flows) rather than surface runoff -- but
also that the only way such a subsurface water supply could be
adequately replenished was if "widespread precipitation" in the form of
rain or snow occurred in the region and then seeped into Mars' porous
ground.

B.M Hynek concluded from MGS' laser topography maps that the western
Arabia Terra ("Arabia Highlands"), an area the size of Europe, was so
eroded by surface rain that 3 million cubic km of its material was
gradually washed into Mars' low-altitude northern plains.

K.P. Harrison and R.E. Grimm examined the fact that the areas on Mars
where valley networks seem to be most concentrated are also those where
MGS' magnetic sensors -- to everyone's surprise -- found local magnetic
fields which seem to be areas where crustal iron minerals have been
permanently magnetized by Mars' long-vanished early magnetic field.

Since this most easily occurs when molten rock is exposed to a magnetic
field at the same time that it is rapidly cooled into solid form, the
obvious possibility is that rising flows of underground magma may have
collided in these areas with large amounts of groundwater kilometers
below the surface, providing a flow of geothermal hot springs for the
valley networks, and also cooling the magma quickly enough to "freeze" a
copy of Mars' magnetic field into the resulting solid rock before Mars'
magnetic field could reverse polarity (which, like Earth's, it probably
did every million years or less) and thus scramble the permanently
recorded "fossil" field.

D.M. Nelson examined the highlands south of the Elysium Basin -- through
which three especially big channels seem to have carried fluid for a
long period -- and concluded that the area showed signs of having
undergone repeated cycles of geological peace that would have allowed a
local layer of ground ice to build up, and episodes of moderate
volcanism just right to melt the accumulated ice and produce large water
flows into Elysium.”  Bruce Moomaw “Mars: A World of Varied
Catastrophes” MARSDAILY <http://www.marsdaily.com/> May 1, 2001
available online athttp://www.spacedaily.com/news/lunarplanet-2001-01a2.html

[85] <#_ftnref85> “Valley networks were examined in detail (25) in
Margaritifer Sinus, a region on the flank of the Arabia bulge and in the
Tharsis

trough (Fig. 3B). Most formed on regions of relatively high topographic
gradient on the flanks of the trough. The majority (;85%) of

observed valley networks here likely formed in Late Noachian time,
between ;4.3 to 3.85 billion years ago (Ga) and ;3.8 to 3.50 Ga

(26), although the possibility exists that earlier valley networks in
this region were destroyed by a high impact flux or alternative

erosion mechanisms. Because many of these valley network orientations
are controlled by Tharsis-induced slopes, the Tharsis load must

be largely Noachian in age, which is consistent with inferences made
earlier. Superposition and sequence relationships indicate that

the valley networks whose azimuths are not explained by the model are
nevertheless contemporaneous with the Tharsis-controlled valley networks
(27). The formation of valley networks in Margaritifer Sinus is
intimately associated with a Late Noachian, large-scale erosion event on
the flanks of the Tharsis trough that stripped at least 1.5 3 106 km3 of

material from this area, leaving behind numerous mesas of Early and
Middle Noachian terrain (25).” Roger J. Phillips et al “Ancient
Geodynamics and Global-Scale Hydrology on Mars” www.sciencemag.org
SCIENCE VOL 291 30 MARCH 2001 available online at

http://ltpwww.gsfc.nasa.gov/tharsis/phillips.tharsis.pdf

[86] <#_ftnref86> Goddard Space Flight Center Educational Programs
[2002] image of Valles Marineris available online at
http://education.gsfc.nasa.gov/experimental/all98invProject.Site/Pages/Vallis.Marineris.html

[87] <#_ftnref87> Image of Valles Marineris

http://www.astronomija.co.yu/suncsist/planete/Mars/marindetalj.htm

[88] <#_ftnref88> http://www.mmedia.is/~bjj/planet_rend/mars_vallesm.jpg

[89] <#_ftnref89> “Figure 1 shows two recent magnetic maps of Mars
derived using these techniques. The anomalies have a pattern strongly
suggestive of faulting and perhaps offset along faults along a major
tectonic structure.  The Vallis Marineris on Mars is a series of large,
fault-bounded canyons which have been compared with major rift
structures on the Earth. The pattern in the magnetic maps, especially
the abrupt truncation of the anomalies at the wall of the canyon,
supports the idea that the Valles Marineris canyon is a tectonic graben.
The maps also suggest that highly magnetic source rocks exist at the
intersection of Coprates and Capri Chasmata, on the northeast corner of
the canyons, and there is a good possibility that these magnetic rocks
may be exposed along the fault wall.” Herbert Frey
<http://denali.gsfc.nasa.gov/personal_pages/frey/frey.html> Geodynamics
2001 The Year in Review available online at

http://denali.gsfc.nasa.gov/annual2001/mgg6

[90] <#_ftnref90> M.E. Purucker et al “Interpretation of a magnetic map
of the Valles Marineris region, Mars” available online at

http://denali.gsfc.nasa.gov/terr_mag/abstract_mars.pdf

[91] <#_ftnref91> “Paleolake deposits have been mapped in Central

Valles Marineris since Mariner 9 and Viking

(McCauley, 1978; Nedell et al., 1988;Witbeck et al., 1991). Accordingly,
the region has been proposed as a priority target for landed payloads
intended to detect diagnostic mineral evidence of a permanent lake
environment, and, especially, biogenic signatures that could have
survived from such promising candidate Martian habitats. (eg, Murray, et
al, 1996; Yen, et al, 1999, Murray, et al, 1999). Just-released MOLA
data strongly buttress the hydrological case for longduration
ice-covered lakes there during Hesperian times at least.” Bruce Murray
[1999] “PALEOLAKE DEPOSITS IN CENTRAL VALLES MARINERIS: A UNIQUE
OPPORTUNITY FOR 2001” Second Mars Surveyor landing site Workshop
available online at

http://web99.arc.nasa.gov/~vgulick/MSLS99_Wkshp/Murray_Paleolakes_VM_abs.pdf

[92] <#_ftnref92> “Carr (1996) suggested that ground water flowed from
the Tharsis uplands into the deep canyons of Valles Marineris before
debouching onto Chryse Planitia in the northern plains. Such a flow may
have persisted for billions of years, and is generally inferred to have
maintained deep lakes beneath which lacustrine sediments accumulated.
Remnants of these Hesperian Age lake deposits survive today as
conspicuous layered

strata in Central Valles Marineris. Just published MOLA data (Smith, et
al, 1999) confirm in detail this topographic trend and, most
importantly, prove that deep, permanent lakes did indeed exist,
especially in Central and Western Valles Marineris. Because the canyons
in the Valles Marineris are deeper than the probable ground water table
at that period, large portions of the canyons would have filled with
water and formed ice-covered lakes.” Ibid. available online at

http://web99.arc.nasa.gov/~vgulick/MSLS99_Wkshp/Murray_Paleolakes_VM_abs.pdf

[93] <#_ftnref93> Valles Marineris Outflow Site (MER-A)
http://marsoweb.nas.nasa.gov/landingsites/mer2003/topsites/VMout/zoom.html

[94] <#_ftnref94> “Recent high resolution MOC images have revealed
the presence of deformed impact craters on flow-like features
characterized by narrow bands of alternating light and dark material
on the walls of Valles Marineris. The maximum crater elongations are
consistent with the flow directions. Moreover the directions of
these flows follow the topography downslope. In some cases, the
flows emanate from cirque-like depressions, and the flows are
divided by sharp ridges similar to arête. These landforms have
resemblance to (1) alpine-type glacier morphology, including
cirques, arêtes, and glaciers containing medial moraines; and (2)
Grand Canyon-type sapping and mass wasting features. Certain aspects
of the features in Valles Marineris seem more consistent with the
first hypothesis involving a viscous rheology of the flows driven by
ice-assisted creep processes. This hypothesis includes direct
analogies to glaciers and rock glaciers. In the case of rock
glaciers, flow is produced by freeze-thaw and by internal
deformation of ice cores or lenses, whereas in the case of glaciers,
movement occurs by internal deformation plus basal sliding in some
cases where the glacier is melted at its bed. The amounts and roles
of ice in the genesis of the Martian glacier-type landforms in
Valles Marineris are not clear at this point. The population density
of undeformed fresh impact craters on these flows appears to be low
compared with the surrounding plateau areas. This may indicate
relatively recent ages of the flow processes.” A.P. Rossi, G.
Komatsu, and J.S. Kargel “[46.03] Flow-like features in Valles
Marineris, Mars: Possible ice-driven creep processes” 31st Annual
Meeting of the DPS, October 1999
Session 46. Mars Surface: Evidence of Change Posters available
online at http://www.aas.org/publications/baas/v31n4/dps99/158.htm

[95] <#_ftnref95> http://www.harmakhis.org/history/7.jpg

[96] <#_ftnref96> “The channel is unusual because it appears to
represent a single outflow initiated by a large impact. This impact
could have excavated materials from the Martian crust from depths of
several kilometers, apparently “tapping” the aquifer system leading to
catastrophic

flooding to form the channel. Ejecta from the Noachian impact crater [6,
7] is preserved NW-W and SE from the source area. The width of
Shalbatana Vallis near its source is about 50 km and then it continues
500 km NE as a sinuous, narrow channel of nearly constant width (10 -20
km cross) and depth (~2 km). The channel then becomes wider (40-50 km),
bifurcates, and enters Simud Vallis [7].” Ronald Greeley and Ruslan
Kuzmin “SHALBATANA VALLIS: A POTENTIAL SITE FOR ANCIENT GROUND WATER”
MSL99 Workshop available online at

http://web99.arc.nasa.gov/~vgulick/MSLS99_Wkshp/Greeley_Kuzmin_Shalbat_abs%20.pdf

[97] <#_ftnref97> “DISCUSSION The irregular shape and lack of
significant downrange ejecta that surrounds Orcus Patera do not help
support an impact origin; it is important to note that Orcus Patera and
Schiller are very similar in shape, but the origin of Schiller is also
poorly understood at present. The average flank slope ETF value of –0.30
found for Orcus Patera is only barely within the –0.30 to –2.33 range
for ETF exponents that were found for other Martian impact craters [6].
Cavity-wall slopes range from 4.33 to 9.65º and are more gradual than
expected for degraded Martian impact craters. The floor of Orcus Patera
is relatively flat, though this appears to be the result of
post-formation lava flooding; the feature’s cross sectional geometry is
thus not typical of an impact crater of this size. MOLA colorstretched
topographic grids around the depression reveal a shape that could be
interpreted as the remnants of a butterfly ejecta pattern commonly
emplaced by elliptical impact craters. However, taken together, these
data provide insufficient grounds for interpreting Orcus Patera as an
impact basin. Unfortunately, Orcus Patera’s elliptical shape, interior
resurfacing, and floor topography also fail to provide enough strong
support for a solely volcanic origin. For instance, the plan view shape
of the basin is similar to that of Long Valley caldera, one of the
largest elongate calderas on Earth. Orcus Patera’s depth below the
surrounding plains and truncated asymmetric flanks, however, are similar
to what is observed for small volcanic edifices in the Tharsis region on
Mars, where subsequent deposits have flooded onto the flanks. Finally,
if Orcus Patera is volcanic in origin, the difference in absolute age
for Orcus Patera’s interior and exterior deposits [9] (volcanic
infilling in the interior is younger than the surrounding flanks)
suggests that the feature had a prolonged volcanic history and multiple
episodes of flooding. Further investigation of relative and absolute
ages for smaller distinct units within this region is necessary to
identify whether volcanism played a key role in the origin of Orcus
Patera or simply modified it subsequent to formation.” D.A. van der Kolk
et al “ORCUS PATERA, MARS: IMPACT CRATER OR VOLCANIC CALDERA?” Lunar and
Planetary Science XXXII (2001) 1085.pdf

http://www.geology.pomona.edu/Mars2000/1085.pdf

[98] <#_ftnref98> “Summary. Geologic mapping of southern Chryse Planitia
and the Xanthe Terra outflow channels has revealed a sequence of fluvial
events which contributed sediment to the Mars Pathfinder landing site
(MPLS). Three major outflow episodes are recognized: (1) broad sheetwash
across Xanthe Terra during the Early Hesperian period, (2) Early to Late
Hesperian channel formation of Shalbatana, Ravi, Simud, Tiu, and Ares
Valles, and (3) subsequent flooding which deepened the channels to their
current morphologies throughout the Late Hesperian. Materials from the
most recent flooding, from Simud and Tiu Valles, and (to a lesser
extent) materials from Ares Vallis, contributed the greatest amount of
sediment to MPLS.” D.M. Nelson, R. Greeley “XANTHE TERRA OUTFLOW CHANNEL
GEOLOGY AT THE MARS PATHFINDER LANDING SITE” Lunar and Planetary Science
XXIX 1158.pdf

http://mars.jpl.nasa.gov/MPF/science/lpsc98/1158.pdf

[99] <#_ftnref99> “Following sheetwash, Mawrth Vallis was formed,
possibly resulting from the discharge of floods from Margaritifer and
Iani Chaos. A broad area of subdued terrain east of Ares Vallis
indicates buried and embayed

craters to the south of Mawrth Vallis. Floods could have passed over
this surface before excavating Mawrth, then drained downslope into
Acidalia Planitia. Alternatively, the subdued area could be a spill zone

formed during the early excavation of Ares Vallis. Channelization
continued in the Late Hesperian with the development of Shalbatana,
Ravi, Simud, Tiu, and Ares Valles. Shalbatana Vallis possibly formed by

subterranean discharge from Ganges Chasmata [7], and Ravi was excavated
by flooding from Aromatum Chaos. Simud and Tiu Valles then developed by
floods from Hydraotes and Hydaspis Chaos, and Ares Vallis developed by
flooding from Iani Chaos. Cross-cutting relationships in Ares and Tiu
Valles suggest that multiple floods occurred within these channels.”
Ibid. http://mars.jpl.nasa.gov/MPF/science/lpsc98/1158.pdf

[100] <#_ftnref100>

http://www.lanl.gov/orgs/pa/News/cover_epi.jpg

[101] <#_ftnref101> http://www.harmakhis.org/history/8.jpg

[102] <#_ftnref102> http://www.harmakhis.org/history/9.jpg

[103] <#_ftnref103> Mike Caplinger  February 1994 “Determining the age
of surfaces on Mars” available online at

http://www.msss.com/http/ps/age2.html

[104] <#_ftnref104> http://www.harmakhis.org/history/9.jpg

[105] <#_ftnref105> “Surfaces on Mars that date to the period of heavy
bombardment are different from the Moon in that processes other than
cratering have    modified the surface both during and, to a lesser
extent, subsequent to the cratering epoch.  This image shows an area in
Mars in the region "Terra Tyrrhena" at about 285 degrees west longitude
and 5 degrees south latitude and shows an area about 500x500
kilometers.  It is fairly typical of areas of the heavily cratered
terrain that have been extensively modified during and immediately after
the period of heavy bombardment.  Most of the large craters have very
smooth floors.” A.D. Howard “Features of Martian Cratered Terrain”
GEOMORPHOLOGY HOME PAGE University of Virginia available online at

http://erode.evsc.virginia.edu/marscrat.htm

[106] <#_ftnref106> “Scarp retreat: Large areas of Mars downslope of the
present-day dichotomy scarp are littered with remnant knobs, and
distinctive valleys – the fretted terrains, eat back into the scarp.
Collectively they

appear to represent ~ 1000 km of scarp retreat in a planet-encircling
belt. Profile analysis suggests that the missing volume represents a
wedge 4 km thick at the present day scarp and tapering to zero over the
1000km width of the belt of fretted and knobbed terrain. Extending this
in a girdle planetwide, we come up with ~5 x 107 km3 –the volume of the
sediments.

Scenario: As the dichotomy collapsed, the slurries would have poured
into the northern lowlands, filling and covering pre-existing cratered
terrain and emplacing thick deposits on a very rapid timescale.
Outgassing from trapped volatile CO2 would produce mud volcanoes [8, 9]
and phreatic cones [10] as CO2 escaped to surface and blasted loose
debris upwards. The northern plains would have been an extensive,

mobile “sea” of fluidised debris – a “Mud Ocean” [1]. Its surface would
have been wreathed in clouds of escaping CO2 from fumaroles, fissures,
and vents. The margin of the Mud Ocean would have been like the

flow front of an aa lava – advancing in a bulldozer-like carpet, burying
and engulfing the surrounding terrain, and steaming from the escape of
CO2. The speed of advance would have been, like lava flows, very

variable and a function of fluid supply behind the flow front. Long
stillstands and episodes of slow creep would alternate with short
intervals of hundreds of metres per day, or more.” N. Hoffman et al
“EMPLACEMENT OF A DEBRIS OCEAN ON MARS BY REGIONAL-SCALE COLLAPSE AND
FLOW AT THE CRUSTAL DICHOTOMY” Lunar and Planetary Science XXXII (2001)
1584.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1584.pdf

[107] <#_ftnref107> K. F. Sprenke and L. L. Baker “POLAR WANDERING ON
MARS?” Lunar and Planetary Science XXXI 1930.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1930.pdf

[108] <#_ftnref108> “Syria Planum: Syria Planum is the site of
long-lived (Noachian to Late Hesperian) magmatic-driven activity with
distinct episodes of intensive early magmatic/tectonic activity that
declined in tectonic

intensity by an order of magnitude from the Late Noachian to Late
Hesperian [2,25], transitioning mainly into a dominantly volcanic
setting during the Late Hesperian [2]. Some of the dominant

characteristics of Syria include: (1) local and regional uplifts, (2)
extensional and contractional tectonism, (3) dike emplacement, including
the formation of Late Hesperian and possibly younger pit crater chains,
(4) volcanism including the formation of shield fields [26] and the
emplacement of voluminous sheet lavas that may range in relative age
from the Late Noachian to the Late Hesperian [2],”

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1811.pdf

[109] <#_ftnref109> “Preliminary results indicate that Syria had a
greater impact on the evolution of the Tharsis magmatic complex than
Alba.” R. C. Anderson et al “COMPARATIVE INVESTIGATION OF THE GEOLOGICAL
HISTORIES AMONG ALBA PATERA AND SYRIA PLANUM, MARS” Lunar and Planetary
Science XXXIII (2002) 1811.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1811.pdf

[110] <#_ftnref110> http://www.harmakhis.org/history/10.jpg

[111] <#_ftnref111> “The Hellas Basin  is an ancient impact structure on
Mars, approximately 3000 km long by 1500 km wide” J. Richardon “Isostacy
in the Hellas Basin on Mars” available online at
http://www.lpl.arizona.edu/~jrich/work/hellasslides.pdf

[112] <#_ftnref112> http://www.lanl.gov/orgs/pa/News/cover_epi.jpg

[113] <#_ftnref113> http://www.harmakhis.org/history/11.jpg

[114] <#_ftnref114> http://www.harmakhis.org/history/6.jpg

[115] <#_ftnref115> http://www.harmakhis.org/history/13.jpg

[116] <#_ftnref116> “The mineral olivine, an iron-magnesium silicate
that weathers easily by water, has been found in abundance on Mars.
The presence of olivine implies that chemical erosion by water is
low on the planet and that Mars has been cold and dry throughout
most of its geologic history.” R. N. Clark and T. M. Hoefen “New
Evidence Suggests Mars Has Been Cold and Dry "Red Planet" Abundant
with Green Minerals” available online at
http://speclab.cr.usgs.gov/mars.press.release.10.2000.html

[117] <#_ftnref117> N. Hoffman “Water on mars? Who are they trying to
kid?” School of Earth Sciences University of Melbourne available online at

http://www.earthsci.unimelb.edu.au/mars/

[118] <#_ftnref118> “Glacial History: There are a variety of distinct
landforms on Mars that are interpreted to be associated with the
presence of ground ice/permafrost [9-11]. Today, the only visible
surface ice occurs at the permanent polar caps, although water ice is
physically stable poleward of 45° N and S latitude. Some investigators
have suggested that the ice cover was once more extensive, particularly
in the southern hemisphere. Kargel [5] mapped the occurrence of a suite
of landforms in Hellas that may have had a common glacial origin. These
features, which he interpreted to be glacial scour marks, moraines,
drumlins, and eskers, are shown in Figure 1.” B. J. Thomson and J. W.
Head “THE ROLE OF WATER/ICE IN THE RESURFACING HISTORY OF HELLAS BASIN”
Fifth International Conference on Mars 6200.pdf
http://www.lpi.usra.edu/meetings/5thMars99/pdf/6200.pdf

[119] <#_ftnref119> “It remains unclear whether the grooved terrain, if
it is indeed glacial in origin, is indicative of a local, isolated
glacier or whether it was part of a more extensive ice sheet in the
southern hemisphere.” Ibid. available online at
http://www.lpi.usra.edu/meetings/5thMars99/pdf/6200.pdf

[120] <#_ftnref120> “Channel and Lacustrine Deposits: Northwards of the
proposed area of maximum glacial extent there is a region interpreted to
be influenced by glacio-lacustrine processes. Kargel [5] mapped a
portion of the shoreline of a possible proglacial lake. The MOLA data
reveal that this mapped shoreline lies almost entirely at the -6000 m
elevation level. Possible sources of input to this lake is water derived
from retreating glaciers as well as outflow channels which empty to
Hellas from the east. The esker field, in which the long axis of the
features in oriented north-south, may represent subglacial flow of water
into a proglacial lake. The eastern channels also might have contributed
to this lake. These small channels resemble other outflow channels

in gross morphology, but are greatly reduced in size. Interestingly,
channel cutting terminates abruptly on the basin floor in a manner that
is very similar to the abrupt cessation of the circum-Chryse outflow
channels. The paucity of tributaries along the length of these Hellas
channels suggests a localized source region, possibly due to
volcano/ground ice interactions.” Ibid. available online at
http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6200.pdf

[121] <#_ftnref121> “Glacial Hypothesis: There are a variety of distinct
landforms on Mars that have been attributed to the presence of ground
ice/permafrost [7-9]. Today, although water ice is physically stable
poleward of 45° N and S latitude, the only visible surface ice occurs at
the permanent polar caps. Some investigators have suggested that the
polar ice cover was once more extensive earlier in Mars’s history [e.g.
10-12]. Kargel and Strom [6] mapped the occurrence of a suite of
landforms in Hellas which they believed share a common glacial origin.
These features, which include glacial scour marks, moraines, drumlins,
and eskers, are proglacial lacustrine deposits, are shown in Figure 1.
The proposed age of the latest episode of glaciation is middle
Amazonian. Three predictions of the glacial hypothesis that we have
investigated with MOLA data are 1) glacial scouring on the south rim, 2)
a shoreline from a pro-glacial lake in the north, and 3) a suite of
glacial depositional landforms on the basin floor.” Bradley J. Thomson
and James W. Head “HELLAS BASIN, MARS: EXAMINATION OF A GLACIAL
HYPOTHEISIS WITH MOLA TOPOGRAPHY” 32-th Vernadsky-Brown Microsymposium /
Abstracts <http://www.geokhi.ru/~planetology/Abstracts.html> available
online at http://www.geokhi.ru/~planetology/Abstracts/Thompson%20et%20al.pdf

[122] <#_ftnref122> Jakupova A. E. et al “PREPARATION OF AN ATLAS OF THE
CRATERING OF MARS” 38^th Vernadsky/Brown Microsymposium on Comparative
Planetology available online at

http://www.geokhi.ru/~planetology/Abstracts/Jakupova%20et%20al.pdf

[123] <#_ftnref123> “In this topographic portrayal of Mars, above, the
northern lowlands are occupied by an ocean (blue) whose shoreline is
placed at the position of Contact 2, the line that Parker and co-workers
interpreted as an ancient shoreline. Thus, this view shows Mars as it
might have looked mid-way through its history according to the oceans
hypothesis. The Tharsis region, with numerous very large shield
volcanoes is seen in the central part of the globe. In the upper right,
many channels flow into the northern lowlands at Chryse Planitia.” NASA
Mars Global Surveyor Project; MOLA Team “Possible configuration of
ancient oceans on Mars: Topographic portrayal of the surface of Mars
derived from Mars Orbiter Laser Altimeter (MOLA) data” available online at

http://www.brown.edu/Administration/News_Bureau/1999-00/99-060g.html

[124] <#_ftnref124> See Figure 2 for shorelines and Figures 3 A to F for
polygons and craters with ejecta lobes.

“Martian impact craters in the 2- to 50-kmdiameter range commonly have
ejecta deposits with distinctive lobe and rampart morphology,
interpreted to be due to the presence of groundwater or ground ice in
the target area that mobilizes the ejecta material (22). Craters on Mars
smaller than a few kilometers generally do not have unusual ejecta
ramparts, and thus the onset diameter of ramparts may be an indication
of the depth at which groundwater or ground ice is encountered during
cavity excavation. On the basis of this concept, Kuzmin et al. (23)
assessed the onset diameter globally. Using their map, we found a
correlation between the lower range of onset diameters (,4 km) and the
northern lowlands (Fig. 3B). The craters with the smallest diameters (,2
km) correlate with the position of the two large basins within the
northern lowlands, a distribution consistent with an interpretation of
groundwater or ground ice occurring preferentially near the surface in
the northern lowlands and particularly in the interiors of the two
basins (7, 8).” James W. Head III et al. “Possible Ancient Oceans on
Mars: Evidence from Mars Orbiter Laser Altimeter Data” 10 DECEMBER 1999
VOL 286 SCIENCE www.sciencemag.org <http://www.sciencemag.org/>
available online at

http://ltpwww.gsfc.nasa.gov/tharsis/mola.ocean.pdf

[125] <#_ftnref125> http://www.harmakhis.org/history/14.jpg

[126] <#_ftnref126> http://www.harmakhis.org/history/15.jpg

[127] <#_ftnref127> “An initial step towards identifying the mechanism
of formation

of Amazonis Planitia is to compare its topographic properties to other
smooth regions with potentially analogous origins. Shown in Figure 4 are
pro_les of elevation collected by various altimeters over smooth
surfaces from a variety of solar system bodies. At the top is MOLA Pass

31 over Amazonis Planitia, where the anomalously smooth region is
observed to extend over 600 km, approximately centered in the plot
(vertical point-to-point accuracy _z _ 0:4 m, horizontal resolution _x _
0:3 km). Below is a Clementine pro_le of the Moon's Oceanus Procellarum
(_z _ 40 m, _x _ 2 km for 1 Hz data and _ 0:2 km for 8 Hz data)

[Smith et al., 1997], Magellan radar altimetry over Niobe Planitia (_z _
4 m, _x _ 10 km) [Ford and Pettengill, 1992], Shuttle Laser Altimeter
data collected over the Sahara desert (_z _ 1:5 m, _x _ 0:7 km) [Garvin
et al., 1997], and shiptracks of Seabeam 2200 bathymetry over the south

Atlantic abyssal plains (_z _ 2 m, _x _ 0:1 km) [Neumann et al., 1996].
The last two pro_les were extracted from the GTOPO data set (highly
variable _z _ 20 m, _x _ 0:1 km) [Gesch and Larson, 1996], _rst over the
Great Plains in the U.S., and second over the Indo-Gangedic Plains
across over the Tibetan Plateau, down across the Tarim Basin and
continuing northwards. Oceanus Procellarum consists of lava flows that
have been broadly tilted by subsidence and locally steepened by tectonic
deformation (wrinkle ridges); their small-scale roughness is dominated
by impact regolith formation processes. Niobe Planitia on Venus consists
of vast lava plains similarly tilted and steepened but not influenced

by regolith formation. Comparison of these surfaces reveals that of
these lowest, smoothest regions observed in the solar system, Amazonis
Planitia closely resembles in its smoothness only the heavily sedimented
surfaces on the Earth, i.e. oceanic abyssal plains and basins _lled by
fluvial deposition processes. It is noteworthy that volcanically
resurfaced terrain is markedly rougher on the Moon, on Venus, and on

Mars, than the peculiar Amazonis deposits. Saharan sand sheets are
rougher by a factor of about three. Other regions in the Martian
northern hemisphere that exhibit evidence of dust deposition are rougher
than Amazonis as well.” Oded Aharonson, Maria T. Zuber and Gregory A.
Neumann “Mars: Northern hemisphere slopes

and slope distributions” GEOPHYSICAL RESEARCH LETTERS, VOL. 25, NO. 24,
PAGES 4413-4416, DECEMBER 15, 1998 available online at

http://ltpwww.gsfc.nasa.gov/tharsis/grl98_slopes.pdf

[128] <#_ftnref128> NASA/JPL/Arizona State University [2003] “Mars
Odyssey THEMIS Image: Lucus Planum”
http://www.marstoday.com/viewsr.html?pid=8867

[129] <#_ftnref129> “RATIONALE: The debouche of Ma'adim Vallis in the
Elysium Basin generated a transitional transported sediment structure,
which planimetric shape is controlled by the enclosing topography of a
deep re-entrant gulf of the Basin into the highland. We defined it as an
estuarine delta. The location and the importance of this estuarine delta
is supported by the theoretical model of graded profile constructed for
Ma'adim Vallis [1], and by two approaches: (i) the reconstruction of
Ma'adim Vallis downstream course from Gusev to Elysium Basin (figure 1),
and (ii) the survey of the sediment deposit in the alleged estuary. The
longitudinal graded profile of Ma'adim Vallis finds its base-level in
the Elysium Basin, at a -1000 m elevation [1], which is in agreement
with the observed Basin shoreline [2]. This model is supported by
observational evidence of flow between the northern rim of Gusev crater,
and the Elysium Basin shoreline. This downstream course of Ma'adim
Vallis can be divided into three hydro geologic regions. Cabrol et al
“Duration of the Ma'adim Vallis/Gusev crater hydrogeologic system, Mars”
/Icarus/ 133, 98-108 [1998].

[130] <#_ftnref130> http://www.space4case.com/mars/mars5/mars112.html

[131] <#_ftnref131> “flowing around the aureole. These three barriers
(degraded Noachian crater rim, proto- Olympus Mons flow unit, and
Olympus Mons aureole) caused subsequent lava flows and outflow channel
effluents, primarily from the Elysium region to the west, to pond on the
floor of Amazonis Planitia, preferentially smoothing the terrain there.
Mars Orbiter

Camera (MOC) images substantiate that at least two very fluid lava flows
alternated with fluvial episodes from Elysium Planitia, flowing through
Marte Valles onto the floor of the Amazonis Planitia basin. Within
Amazonis Planitia, MOC images show flow-like textures heavily mantled by
sediments, and radar data reveal the presence of rough lava flow
surfaces underlying the sedimentary debris. These data thus suggest that
the unique smoothness of Amazonis Planitia is the result of deposition
of thin fluid lava flows and fluvial sediments in an enclosed basin.
Crater counts suggest that the most recent resurfacing may have occurred
in the latest Amazonian Period, in the last 1% of the history of Mars.”
Elizabeth R. Fuller and James W. Head III “Amazonis Planitia: The role
of geologically recent volcanism and sedimentation in the formation of
the smoothest plains on Mars” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107,
NO. E10, 5081, doi:10.1029/2002JE001842, 2002 available online at

http://www.planetary.brown.edu/planetary/documents/2682.pdf

[132] <#_ftnref132> “Introduction: This study seeks to understand origin
of the equatorial layered deposits (ELDs), including the Medusae Fossae
Formation (MFF) the filled craters of Elysium and Arabia Planitiae (

Gusev and Henry Craters). Several origin hypotheses have been proposed
for the MFF [c.f. summary in most involving a pyroclastic origin but one
proposing formation at the poles [2]. Previous work using MOLA to test
the polar formation theory found there are both similarities and
significant differences between the equatorial and polar layered
deposits, concluded that the MFF may be volatile rich, but not form at
the poles [3]. Another MOLA-based study similarly found that the
deposits were not polar origin, and instead concluded that they were
most consistent with a welded ashfall tuff [4]. [5] further showed that
the ELDs could not be evidence of polar wander on the basis of the time
scales necessary for polar wander to have occurred. Morphological
evidence also indicates that while there are similarities between the
poles and the ELDs, including extensive layering at multiple scales,
unusual smoothness at several scales [see also discussion in steep
slopes (~1-6° in the MFF, ~1-10° at the poles), and distal thinning of
the materials, there are fundamental differences, notably the lateral
extent the ELDs: the MFF itself reaches across 90 longitude (Figure 1),
and filled craters are present around the globe. If the ELDs did form by
mechanism similar to that of the poles, what were sources of the
volatiles, and how did they reach equator?

Volatile sources: There are three Amazonian-aged volatile sources in the
equatorial region: degassing from nearby volcanism, Elysium-region
catastrophic outflow, and polar material migration during periods

high obliquity. 1) Degassing: The Tharsis Montes, Olympus Mons, and
Elysium Mons were all active during the Amazonian. [7] showed that these
eruptions were most likely plinian, with extensive magmatic degassing
releasing CO2 and H2O. Regional outflow: [8] and [9] have shown that
waterrich debris flowed down the northwestern flanks Elysium Mons in the
mid-late Amazonian. Additionally, in the late Amazonian there was
repeated catastrophic release of water in Elysium Planitia, through
Marte Vallis, debouching into Amazonis Planitia [10]. 3) Migration of
polar materials: periods of maximum obliquity, the poles receive more
insolation than the equator. As the poles warm, ice becomes unstable and
is forced to migrate to a new cold trap (see below) [11].” E. R. Fuller
and J. W. Head, III “PROPOSING A HIGH VOLATILE CONTENT IN THE EQUATORIAL
LAYERED DEPOSITS INCLUDING THE MEDUSAE FOSSAE FORMATION, MARS”
Microsymposium 36, MS022, 2002 Available online at

http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/022_Fuller_Head.pdf

[133] <#_ftnref133> “Probably the most important question concerning
the global-scale tectonic history of Mars is the origin of the
crustal dichotomy. The northern lowland is not only several
kilometers lower than the southern highland, it also is surfaced by
materials that are significantly younger than surface materials in
the southern highland (Scott and Tanaka, 1986; Greeley and Guest,
1987; Tanaka and Scott, 1987). The young surface materials in the
lowland rest unconformably on basement material having an age
comparable to the exposed ancient highland terrane to the south
(Scott, 1978; Maxwell and McGill, 1987; McGill, 1989; McGill and
Dimitriou, 1990; Schultz and Frey, 1990).” George E. McGill
“Geologic Map Transecting the Highland/Lowland Boundary Zone, Arabia
Terra, Mars: Quadrangles 30332, 35332, 40332, AND 45332” available
online at

http://geopubs.wr.usgs.gov/i-map/i2746/

[134] <#_ftnref134> “Tectonics: In the highlands of Amenthes-northern
Terra Cimmeria and northern Arabia Terra, lobate scarps are found
between approximately 200 to 600 km south of the dichotomy boundary.
These lobate scarps, interpreted to be the surface expression of thrust
faults, are oriented roughly parallel to the dichotomy boundary (Figure
1). The proximity and parallel orientation of thrust faults to the
dichotomy boundary suggests that compressional deformation was involved
in its formation

[2]. Extension along the boundary is thought to have occurred during the
Late Noachian to Early Hesperian [3]. Thrust faulting of the highlands
near the boundary appears to have occurred during roughly the same
period [2, 4]. Thus the fractures and thrust faults may reflect a
tectonic event that was associated with the dichotomy boundary (Figure
1). The deformation along the boundary suggests that the dichotomy
formed in the Late Noachian to Early Hesperian [2, 3]. If the dichotomy
formed earlier, this deformational event may have been responsible for
shaping the present-day dichotomy boundary in the eastern hemisphere.”

T. R. Watters “THE TECTONICS AND TOPOGRAPHY OF THE DICHOTOMY BOUNDARY IN
THE EASTERN HEMISPHERE OF MARS” Lunar and Planetary Science XXXIII
(2002) 1692.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1692.pdf

[135] <#_ftnref135> “Distinctions include: (1) magmatic-driven activity
from at least the

Early Hesperian extending into the Amazonian [1,7-8]” R. C. Anderson et
al. “COMPARATIVE INVESTIGATION OF THE GEOLOGICAL HISTORIES AMONG ALBA
PATERA AND SYRIA PLANUM, MARS” Lunar and Planetary Science XXXIII (2002)
1811.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1811.pdf

[136] <#_ftnref136> “4. Conclusions

[93] Detrended MOLA altimetry data have provided a new picture of the
Martian northern lowland basin topography, morphology, evolution, and
relation to the history of Mars. We interpret our results to indicate
that the northern lowlands are underlain by a regional unit containing a
basin-wide system of subparallel wrinkle ridges and arches. This unit is
laterally contiguous with Hesperian-aged ridged plains in the southern
uplands and contains highly modified craters, the number of which
suggests an Early Hesperian age. The orientation and location of the

wrinkle ridges in the North Polar Basin completes a global circum-

Tharsis ridge system forming a band approximately 7000 km wide and
extending over the whole circum-Tharsis region. Several subareas of the
northern lowlands show individual patterns (e.g., basin-like areas of
Isidis and Utopia). The present spacing and height of wrinkle ridges and
geometry of buried craters in the northern lowlands suggest that the
Late Hesperian Vastitas Borealis Formation is a sedimentary unit
superposed on Hr (regional plains). Hesperian-aged channels entering
Chryse Planitia are controlled by the orientation and topography of
wrinkle ridges deep into the basin, indicating that wrinkle ridges had
largely formed by Late Hesperian. These channels are among the strongest

candidates for providing the material of the Vastitas Borealis
Formation. Amazonian-aged smooth plains units of volcanic origin,
particularly in Amazonis Planitia, further bury and obscure the
underlying wrinkle ridges and the Vastitas Borealis Formation. [94]
Recognition of these units and their stratigraphic relationships
provides a new perspective on the history of the northern lowlands
(Figure 17). In this scenario, in the Early Hesperian the majority of
the northern lowlands was filled with volcanic plains similar to those
presently exposed in the southern uplands (Hr). As with those deposits
in the southern uplands, evidence for volcanic vents was scant or
subdued in topography. The Hesperian-aged plains in the northern
lowlands were pervasively deformed soon thereafter by
Tharsis-circumferential and basin-related wrinkle ridges. Circum-Chryse
outflow

channels formed in the Late Hesperian following courses largely
controlled by wrinkle ridge orientation and height and deposited
material in the basin to form a major contribution to the Vastitas
Borealis Formation.

[95] Widespread emplacement of the Hesperian-aged ridged

plains of apparent volcanic origin is interpreted to mean that the

volcanic phase represented by this unit was global in nature and
resurfaced the northern lowlands, in addition to the _10% of the

planet previously known, for a total resurfacing of about 30% of

Mars. This remarkable event increases by a factor of 2 the amount

of volatiles that might have been degassed into the atmosphere

during this time period of peak volcanic flux.” James W. Head III et al.
“Northern lowlands of Mars: Evidence for widespread volcanic flooding
and tectonic deformation in the Hesperian Period” JOURNAL OF GEOPHYSICAL
RESEARCH, VOL. 107, NO. 0, 10.1029/2000JE001445, 2002 available online at

http://www.planetary.brown.edu/planetary/documents/2575.pdf

[137] <#_ftnref137> “[1] We analyze the fate of the Hesperian-aged
outflow channel effluents emplaced into the northern lowlands of Mars.
We have modeled the evolution of these effluents under the assumption
that they were emplaced under a range of atmospheric conditions
comparable to those of today and thought to have prevailed in the
Hesperian. Under these conditions we find that the evolution of the
sediment-loaded water after it left the channels includes three phases.
Phase 1: Emplacement and intensive cooling: Violent emplacement of water
followed by a short period of intensive evaporation from the surface and
near-surface layer, and intensive convection. During this phase the
water maintained and redistributed its large suspended sediment load.
Water vapor strongly influenced the climate, at least for a geologically
short time. When the temperature of the water reached the temperature of
the maximum density or the freezing point, boiling and intensive
convection ceased and the water deposited the sediments. Phase 2:
Freezing solid: Geologically rapid freezing of the water body
accompanied by weak convective water movement occurred over a period of
the order of _104 years. Phase 3: Sublimation and loss: This period
involved sublimation of the ice and lasted longer than the freezing
phase. The rate and latitudinal dependence of the sublimation, as well
as the location of water vapor condensation, crucially depend on the
planetary obliquity, climate, and sedimentary veneering of the ice.
Phase 3 would have been very short geologically (_105–106 years) if an
insulating sedimentary layer did not build up rapidly. If such an
insulating layer did form rapidly, sublimation could cease and residual
ice hundreds of meters thick could remain below the surface today.”
Mikhail A. Kreslavsky and James W. Head “Fate of outflow channel
effluents in the northern lowlands of Mars: The Vastitas Borealis
Formation as a sublimation residue from frozen ponded bodies of water”
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. E12, 5121,
doi:10.1029/2001JE001831, 2002 available online at

http://www.planetary.brown.edu/planetary/documents/2686.pdf

[138] <#_ftnref138> “Resurfacing: We suggest that the latest resurfacing
of the northern plains did not occur by sedimentation within an ocean or
by widespread volcanism, but rather by the latest stages of long-term
periglacial and thermokarst modification, with progressively reduced
intensity occurring during the Hesperian through Early Amazonian. This
activity obliterated or heavily modified earlier landforms, resulting in
huge collapse structures, ghost craters, valley networks,
highland/lowland fretted and knobby terrains, polar cavi terrains, and
lowland thumbprint terrains. Such resurfacing likely involves erosion,
ductile deformation, collapse, and effusive and violent eruptions of
volatile charged material. The elevation dependence of the reworking may
be related to gradual lowering of the threshold for near-surface
volatile activity, as governed by the composition and distribution of
subsurface volatiles and by the geothermal gradient. The difficulties to
making Mars warm in the past and the lack of significant chemical
weathering on Mars [14] seem to preclude substantial liquid water at the
surface in the form of long-lived fluvial, lacustrine, and wet-based
glacial activity. Instead, northern plains resurfacing may result mainly
from the subsurface activities of both H2O and CO2 (CO2 being more
volatile), as well as from local discharges of sediment enriched with
these volatiles.”

K. L. Tanaka et al “RESURFACING OF THE NORTHERN PLAINS OF MARS BY
SHALLOW SUBSURFACE, VOLATILEDRIVEN ACTIVITY” Lunar and Planetary Science
XXXIII (2002) 1406.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1406.pdf

[139] <#_ftnref139> “CO2 and Warm H2O Models: The simplest and most
self-consistent model for the morphologies we see in and Athabasca
Vallis and nearby “flood” valleys is that a volatile-rich debris flow
was deposited and sculptured by roller vortices to produce the flow
parallel ridges which were impregnated with the flow volatiles (Figure
3a). Given likely flow velocities, thicknesses, and rheology, roller
vortices actually are only stable for debris flows and density flows
(and not for aqueous floods or lava flows) [1]. In the immediate
aftermath of the flow, escape of highly volatile fluids from the ridges
generated longitudinal chains of phreatic cones in a cryovolcanic
process (Figure 3b). The most reasonable explanations for the Athabasca
Vallis and its ridges of cones appears to be debris flows charged with
warm water and/or CO2 gas-. Implications For Local And Regional Geology:

Whilst Athabasca Vallis is currently targeted as a MER 2003 backup
candidate landing site, due to the evidence for recent outburst floods,
the terrain does not require aqueous action. Instead, massive CO2-rich

gas-supported density flows may have resulted from outburst of
subsurface liquid CO2 reservoirs rather than liquid water reservoirs.”

Nick Hoffman and Ken Tanaka “CO-EXISTING “FLOOD” AND “VOLCANIC”
MORPHOLOGIES IN ELYSIUM AS EVIDENCE FOR

COLD CO2 OR WARM H2O OUTBURSTS” Lunar and Planetary Science XXXIII
(2002) 1505.pdf

http://www.earthsci.unimelb.edu.au/mars/LPSC_2002_1505_Athabasca.pdf

[140] <#_ftnref140> “Fluvial geomorphology. The fluvial nature of the
Marte Vallis outflow channel appears to be confirmed by MOC images [10]
that show streamlined islands of several hundred meters to a couple of
kilometers across, longitudinal grooves ten's of meters wide, and
multi-level terraces on channel islands and margins. In conjunction with
the anastomosing plan form of the channels, these features suggest
channel formation by a high volume of low viscosity fluid that we
hypothesize was sediment-laden water. Similar features also appear in
MOC images to the north and west of the Elysium Basin, indicating the
presence of some channels more substantial than previously supposed.” D.
M. Burr et al “RECENT FLUVIAL ACTIVITY IN AND NEAR MARTE VALLIS, MARS”
Lunar and Planetary Science XXXI 1951.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1951.pdf

[141] <#_ftnref141> See images in

http://webgis.wr.usgs.gov/mer/March_2002_presentations/Burr/Burr-Landingsite3.pdf

[142] <#_ftnref142> “Discussion: MOC images have not shown many smaller
networks as would be expected from precipitation. Malin and Carr [13]
have suggested that the global lack of such dendritic channels may be
due to modification by eolian and mass-wasting processes. However, the
lava and channel

morphologies of the Elysium Basin region appear pristine. The dendritic
channels, then, are likely absent from MOC images of the Elysium Basin
because they did not form there. In addition, the anastomosing form of
the channels suggests formation by exceptionally large flow. Thus, we
believe that the MOC data fails to support the idea that the channel
flood water derived from precipitation.” D. M. Burr “RECENT FLUVIAL
ACTIVITY IN AND NEAR MARTE VALLIS, MARS” Lunar and Planetary Science
XXXI 1951.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1951.pdf

[143] <#_ftnref143> “Secondary geomorphic evidence: rootless cones.
Rootless cones are seen throughout Athabasca Valles and the unnamed
northern channel system, as well as in Amazonis Planitia, into which the
Marte Vallis debouches [5]. Rootless cones form when lava flows over and
intimately mixes with wet substrate, volatilizing the water which then
erupts up through the overlying lava flow [5]. Rootless cone fields within

the channels, but not on the surrounding terrain, suggest that the water
for their formation was emplaced by aqueous flow within the channels.”

D. M. Burr et al “EXTENSIVE AQUEOUS FLOODING FROM THE CERBERUS FOSSAE,
MARS, AND ITS IMPLICATIONS FOR THE MARTIAN HYDROSPHERE” Lunar and
Planetary Science XXXIII (2002) 1047.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1047.pdf

[144] <#_ftnref144> “Source of the sediment: The sediment deposited in
the streamlined forms was in transport by the floodwater. The
floodwaters would have been carrying material entrained from the Martian
surface during

the carving of Athabasca Vallis. Because they emanated from the Cerberus
Fossae, the floodwaters may also have been carrying sediment from within
the Fossae. Since the Fossae were a source for both water and lava, this
sediment may have been hydrothermally altered. Athabasca Vallis was a
candidate landing site for the Mars Exploration Rovers. If future landed
missions target Athabasca Vallis, they may be able to collect sediment
samples from the streamlined forms of such subsurface material.” D. M.
Burr “TEMPORARY PONDING OF FLOODWATER IN ATHABASCA VALLIS, MARS” Lunar
and Planetary Science XXXIV (2003) 1066.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1066.pdf

[145] <#_ftnref145> “[12]   The Cerberus Fossae fissures (Figure 1C
<javascript:openfigures('fig01')>) have very sharp edges and steep
slopes (>80° indicated by shadows and viewing geometry in M04-03770) and
cut sparsely-cratered plains (e.g., M07-03839). Thus, although their
structural trend is also observed in remnant ancient highland terrain
[Tanaka et al., 1992 <javascript:openreferences('tana92')>], we deduce
the fissures to have been recently reactivated. That they appear to have
been the source, not only of recent lava flows, but also of recent
voluminous aqueous flooding, supports a causative relationship between
the two types of flows, such as a scenario in which rising dikes melt
ground ice [e.g., McKenzie and Nimmo, 1999
<javascript:openreferences('mcke99')>] and open pathways to the surface.
By analogy, the easternmost Cerberus Fossae could have been the main
source for the larger aqueous floods down Marte Vallis [Tanaka et al.,
1992 <javascript:openreferences('tana92')>], although geomorphic and
topographic evidence may now be largely buried beneath Cerberus Plains
lavas. Burr, D. M “4. Source of the Flood Water” GEOPHYSICAL RESEARCH
LETTERS, VOL. 29, NO. 1, 10.1029/2001GL013345, 2002

http://www.agu.org/pubs/sample_articles/sp/2001GL013345/4.shtml

[146] <#_ftnref146> “Note the number of channels in this image. In
places, these features look a lot like lunar sinuous rilles. They are
all large flat-bottomed valleys. They begin abruptly in broad
depressions. And their sources seem to form a ring centered on Elysium
Mons. Like sinuous rilles on the Moon, these valleys might be lava
channels. However, water is a more likely cause for their formation.
Specifically, ground ice appears to have been widespread in the Elysium
region. Such ice is easily melted near hot magmas. Thus, melt water
provides a ready source for erosion in the Elysium region. Further, the
loss of a lot of ground ice can cause collapse depressions near the
channel sources.” S. De Silva “Elysium Mons” University of South Dakota 
available online at

http://volcano.und.nodak.edu/vwdocs/planet_volcano/mars/Shields/elysium.html

[147] <#_ftnref147> Mars Odyssey and MGS Mars Orbital Laser Altimeter
(MOLA) Science teams “Mars Odyssey Orbiter Watches a Frosty Mars” [2003]
available online at

http://mars.jpl.nasa.gov/odyssey/newsroom/pressreleases/20030626a.html

[148] <#_ftnref148> “Due to the presence of two distinct phases of
volcanism of such differing characteristics, it is proposed that these
phases were separated by a period of repose. During this time the magma
chamber, which had supplied the Elysium Mons vent, cooled sufficiently
to alter the regional stress fields and produce tectonic activity
observed in the Elysium Mons area e.g. arcuate graben. It is suggested
that the chamber cooled sufficiently to act as a regional “plug” thus
preventing

magma from the second phase of volcanism following the same course to
the surface as that of the first phase. A repose period of 10 Ma has
been estimated as a period of time sufficient to allow a magma chamber
of 1100 km.” S.P. Bowling “Modelling the Effusion Rates and Activity
Phases of the Elysium Volcanics” Lunar and Planetary Science XXX 1185.pdf

http://www.lpi.usra.edu/meetings/LPSC99/pdf/1185.pdf

[149] <#_ftnref149> “The whole of north Terra Meridiani (centered at
lat. 0°, long. 0°) contains an unusual and enigmatic terrain unit. On
the equatorial geologic maps of Mars, this highland area was mapped as
being surfaced by two units of Noachian age: a subdued crater unit and
an etched unit [1,2]. The subdued crater unit is a plains unit marked by
subdued and buried old crater rims and was interpreted to be thin,
interbedded lava flows and eolian deposits that partly bury underlying
rocks [1,2]. The etched unit was described as being deeply furrowed by
grooves that produce an etched or sculptured surface and was interpreted
to be ancient cratered material degraded by wind erosion, decay of
ground ice, and minor fluvial erosion [1,2].” M. G. Chapman “2001 SITE
IN NORTH TERRA MERIDIANI: THE TES CONCENTRATION AREA” MSL99 Workshop
available online at

http://web99.arc.nasa.gov/~vgulick/MSLS99_Wkshp/Chapman_Hem_abs_pg1.pdf

[150] <#_ftnref150> http://www.harmakhis.org/history/16.jpg

[151] <#_ftnref151> N. Hoffman “Outburst floods as cold and dry
avalanches” available online at

http://www.earthsci.unimelb.edu.au/mars/Outburst.html

[152] <#_ftnref152> http://www.harmakhis.org/history/19.jpg

[153] <#_ftnref153> “Interpretation: We interpret the fan shaped
deposits found at the base of the Olympus Mons escarpment as remnants of
glaciers, in agreement with Lucchitta [4]. It is important to consider
what type of glacier. The con-tinuous, curvilinear ridges found on the
surface of Unit C are very similar to rock glaciers. The source region,
the basal escarpment, provides the topographic relief re-quired to
provide the debris. The linear ridges found in the lower left region of
the image are interpreted as the remnants of lateral moraines, which
were deposited as the glacier retreated and then eroded again as the
glacier advanced. This implies several episodes of advance and retreat.

However, there is no cirque-like source for the de-posits. Instead, they
extend from somewhat linear seg-ments of the basal scarp. Additionally,
the fan shaped deposits are much larger than terrestrial rock glaciers;
they extend many tens of km rather than up to a few km. Thus, we
interpret these features to be the remnants of debris-covered glaciers,
which are morphologically simi-lar to rock glaciers but contain more ice
and therefore flow more like valley glaciers and cover greater dis-tances.

We thus envision the following scenario: glacial ice builds up on the
northwestern slope of the basal escarp-ment. Debris from the escarpment
is deposited on top of the ice. As the glacier flows to the northwest,
it spreads and develops a spatulate form. Several periods of ad-vance
and retreat are recorded by the eroded lateral mo-raines. At the
furthest extent of advance, the glacier de-posited a large terminal
moraine. This moraine has now degraded, perhaps by sublimation of
internal ice blocks or removal of debris through aeolian erosion. This
has left the hummocky material in unit B.

Discussion: Lucchitta [4] also identified glacier-like features at the
nearby Tharsis Montes. Recent analysis of MOLA topography data confirm
this result and conclude that cold-based glaciers were once on the
west-northwest flanks of Arsia Mons [16, 17] and Pavonis Mons [18, 19].
Cold-based glaciers are made up of ice that is entirely below the
melting point; thus, it flows through internal deformation and there are
no melting features associated with the glacier. It is likely that most
mountain glaciers on Mars would be cold-based [17].

The glacial features found around the Tharsis Montes are far more
extensive than those at Olympus Mons. This implies that a greater
quantity of ice was available at the Tharsis Montes. Since all of these
volcanoes are in the equatorial regions, it seems likely that they were
glaciated at the same time. If water ice were stable at one location, it
should be stable at the others. However, the fact that Olympus Mons had
smaller glaciers implies that the conditions there were not as favorable
for surface ice.

One possibility is that Olympus Mons was more active at the time; a
higher geothermal flux in this region could prevent large build-ups of
ice.” S. M. Milkovich and J. W. Head, III “OLYMPUS MONS FAN SHAPED
DEPOSIT MORPHOLOGY: EVIDENCE FOR DEBRIS GLACIERS” Sixth International
Conference on Mars (2003) 3149.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3149.pdf

[154] <#_ftnref154> See Figure 1, also

“Introduction: Tharsis Montes cap the broad Tharsis Rise (Fig. 1), a
huge center of volcanism and tectonism spanning almost the entire
history of Mars. Each of the Tharsis Montes, although largely
constructed of effusive and explosive volcanic deposits, contains a
distinctive and unusual lobe, or fan-shaped deposit on their western
flanks. On the basis of their unusual nature and superposition
relationships, they have attracted attention since they were first
described from Mariner 9 and Viking data [1]. These deposits, as
exemplified by those on Arsia Mons [e.g., 2,3], usually contain three
facies: 1) An outermost ridged facies, consisting of a broad thin sheet
characterized by numerous ridges, 1->10 km in length, and spaced a few
hundred meters to several kilometers apart, that extend over topographic
barriers without obvious deflection. 2) A knobby facies, which forms an
extensive area of chaotic terrain that consists of surrounded
several-kilometer-diameter hills; some hills are elongated downslope,
and others form chains that are

parallel to subparallel to the ridges in the ridged facies. 3) A smooth
facies, which contains arcuate lineations and

diffuse to lobate margins; the smooth facies appears to overlie areas of
the knobby facies.” J. W. Head “MOUNTAIN GLACIERS ON MARS?
CHARACTERIZATION OF WESTERN THARSIS MONTES FAN SHAPED DEPOSITS USING MGS
DATA” Mars atmosphere modeling and observations workshop [2002]
available online at

http://www-mars.lmd.jussieu.fr/granada2003/abstract/head.pdf

[155] <#_ftnref155> “In mid-October the frozen carbon dioxide, which
seasonally caps Mars' north pole, evaporated enough to give Odyssey's
scientists their first chance to look there for ice. "We are really
excited about what we are seeing in the north polar region of Mars. With
the seasonal carbon dioxide frost gone, we can see evidence of massive
amounts of water ice in the soil, even more than we found in the south,"
said Dr. William Boynton, principal investigator for Odyssey's gamma-ray
spectrometer suite at the University of Arizona, Tucson.” “NASA's
Revealing Odyssey” MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY
http://mars.jpl.nasa.gov/odyssey/newsroom/pressreleases/20021207a.html

[156] <#_ftnref156> “"Once the carbon-dioxide layer disappears, we see
even more water ice in northern latitudes than Odyssey found last year
in southern latitudes," said Odyssey's Dr. Igor Mitrofanov of the
Russian Space Research Institute (IKI), Moscow, lead author of a paper
in the June 27 issue of the journal Science. "In some places, the water
ice content is more than 90 percent by volume," he said. Mitrofanov and
co-authors used the changing nature of the relief of these regions,
measured more than 2 years ago by the Global Surveyor's laser altimeter
science team, to explore the implications of the changes.” Mars Odyssey
and MGS Mars Orbital Laser Altimeter (MOLA) Science teams “Mars Odyssey
Orbiter Watches a Frosty Mars" available online at
http://mars.jpl.nasa.gov/odyssey/newsroom/pressreleases/20030626a.html

[157] <#_ftnref157> T. N. Titus (Oak Ridge Associated Universities), H.
H. Kieffer, K. F. Mullins (U.S. Geological Survey) “TES Observations of
the South Pole” available online at http://www.mars-ice.org/crocus.html

[158] <#_ftnref158> Timothy N. Titus, Hugh H. Kieffer, Kevin F.
Mullins, Phillip Christensen “Slab Ice and Snow Flurries in the Mars
Northern Polar Night” available online at

http://www.mars-ice.org/cold.html

[159] <#_ftnref159> “Discussion: The narrowness of the size distribution
combined with the size cutoff at smaller and larger  sizes points toward
a period in the history of this area of the residual cap where
Swiss-cheese features were forming. It is hard to imagine what may be
varying on timescales of centuries to control whether environmental
conditions are suitable for Swiss-cheese formation or not. Orbital
change cannot be playing a significant role over such short timescales
and the atmosphere generally has no memory from one year to the next.
One possibility is perhaps the slow redistribution of dust on a planet
wide scale into preferred areas, which changes the albedo pattern with
respect to the (by comparison) invariable elevation pattern. This could
possibly switch the climate and circulation patterns into some other
mode leading to differing conditions on the residual cap and a reseting
of dust to its original configuration. This dust redistribution action
may also act on more regional or local scales, changing the environment
only in the near polar areas.” S. Byrne et al “Martian Climactic Events
Inferred from South Polar Geomorphology on Timescales of Centuries”
Lunar and Planetary Science XXXIV (2003) 3112.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3112.pdf

[160] <#_ftnref160> “Introduction: The origin of the layering
characteristic of the Polar Layered Deposits (PLD) of Mars is

generally not thought to arise from the flow of the water ice presumed
(along with dust) to comprise

these layers, since rheological modeling indicates that Mars is
presently too cold to permit substantial ice

flow in the polar regions. However, Martian obliquity deviates
chaotically from its current Earth-like value of 25º, surpassing 45º
within the last several Myr. Not only will the polar regions receive
additional insolation at these high obliquities, but the resulting
increase in H2O sublimation from the ice caps will initiate a water
vapor greenhouse heating effect. Hence, surface and subsurface
temperatures will be elevated at high obliquity, leading to dramatic
increases in ice flow velocities.” Asmin V. Pathare and David A. Paige
“Enhanced Ice Flow at High Martian Obliquity: A Rheological Model of the
Polar Layered Deposits” Lunar and Planetary Science XXXI 1571.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1571.pdf

[161] <#_ftnref161> “The observation of these changes and the rate at
which they are occurring is akin to the observations of the "ozone hole"
over Antarctica, or the steady increase in atmospheric CO_2 in the
Earth's atmosphere. Although the implications of these observations is
often hotly debated (with most scientists convinced that they represent
evidence for the impact of humans on the terrestrial climate), everyone
agrees that they are evidence of contemporary climate change. Mars, too,
is experiencing climate change today. We don't know what it means, or
how extensive the changes may be, but we can now propose tests for
future observations that can begin to address these questions.” Malin
Space Science Systems Team “Evidence for Recent Climate Change on Mars”
available online at

http://mars.jpl.nasa.gov/mgs/msss/camera/images/CO2_Science_rel/malin_etal.html

[162] <#_ftnref162> “Introduction: Recent work has shown, surprisingly,
that active channel systems exist in widespread but specific locations
on Mars [1]. Although conventionally interpreted as evidence for water
flow, their context more firmly argues for the involvement of CO2 at
cryogenic temperatures, and argues against liquid water. Channels within
the South polar cap at 71o South are fresh and presumably carry annual
flows as the pole cap ablates each spring. These are the freshest
evidence for channels anywhere on Mars, with activity within the last
Martian year. The temperature at this location has an annual mean around
200K making liquid water a very difficult proposition, in sufficient
quantity to carry sediment 1.5 km downslope.” N. Hoffman LPSC [2001]
available online at

http://www.earthsci.unimelb.edu.au/mars/LPSC2001_Hoffman_Polar.pdf

[163] <#_ftnref163>
http://www.msss.com/moc_gallery/m07_m12/images/M10/M1003736.html

[164] <#_ftnref164> http://www.harmakhis.org/paper/

[165] <#_ftnref165> They can all be seen online at

http://www.harmakhis.org/

[166] <#_ftnref166> http://www.harmakhis.org/paper/water/

[167] <#_ftnref167> A spreadsheet using this formula is illustrated
here. By inserting coordinates of other images their Pole 4 latitude can
be calculated.

http://www.harmakhis.org/history/example.xls

[168] <#_ftnref168>
http://www.harmakhis.org/paper/water/craterchanneldata.htm

[169] <#_ftnref169> http://www.lanl.gov/orgs/pa/News/cover_epi.jpg

specifically

http://www.harmakhis.org/history/9.jpg

[170] <#_ftnref170> “Gullies seen on martian cliffs and crater walls in
a small number of high-resolution images from the Mars Global Surveyor
(MGS) Mars Orbiter Camera (MOC) suggest that liquid water has seeped
onto the surface in the geologically recent past. The gully landforms
are usually found on slopes facing away from mid-day sunlight, and most
occur between latitudes 30° and 70° in both martian hemispheres. The
relationship to sunlight and latitude may indicate that ice plays a role
in protecting the liquid water from evaporation until enough pressure
builds for it to be released catastrophically down a slope. The relative
freshness of these features might indicate that some of them are still
active today--meaning that liquid water may presently exist in some
areas at depths of less than 500 meters (1640 feet) beneath the surface
of Mars.” “MOC Images Suggest Recent Sources of Liquid Water on Mars”

MGS MOC Releases MOC2-234 to MOC2-245, 22 June 2000 available online
athttp://mars.jpl.nasa.gov/mgs/msss/camera/images/june2000/

[171] <#_ftnref171> “2. Occurrence in Regional Clusters. This
observation was stated in the original paper [1], and is amplified by >
2 Mars years’ worth of data. Gullies occur in regional clusters. Gaps,
in which no gullies occur between clusters, are observed. More gullies
occur in the

southern hemisphere than the north.” K. S. Edgett et al “POLAR- AND
MIDDLE-LATITUDE MARTIAN GULLIES: A VIEW FROM MGS MOC AFTER 2 MARS YEARS
IN THE MAPPING ORBIT” Lunar and Planetary Science XXXIV (2003) 1038.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1038.pdf

[172] <#_ftnref172> “Debris flows in French Alps: Best analogs to
Martian gullies are debris flows from Greenland [4] and Canada [7] which
occur over a permafrost. Debris flows in the Alps sometimes occur over a
permafrost but this is not the case usually. They nevertheless consist
of good analogs for the properties of the flow and the geometry. The two
examples shown fit the association of alcove at the gully head and
channel with levees. They have been triggered by snow melting in the
springtime or strong showers in summer, thus external processes only.
The debris flows of the Izoard do not show any springs at the head (Fig.
1). One spring has been observed in the valley 400m in elevation under
the gully head and no debris flows alcove is observed at this location.
The debris flows of Izoard formed in 1985 and they have overflow the
road located at mid-slope. They are typically 10 m large with 2 m high
levees.” N. Mangold et al “FORMATION OF GULLIES ON MARS: WHAT DO WE
LEARN FROM EARTH?” Sixth International Conference on Mars (2003) 3048.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3048.pdf

[173] <#_ftnref173> “3. Association with Layers. This observation was
also stated in the original paper [1]. We reiterate it here after
examining ~1300 images. Any model for the origin of gullies must explain
the relationship with layers. Gully channels typically head at a
specific layer exposed on a given slope (e.g., Fig. 1). Within a given
regional cluster, gullies may all head at the same layer where it is
exposed in different crater and trough walls.” K.S. Edgett et al “POLAR-
AND MIDDLE-LATITUDE MARTIAN GULLIES: A VIEW FROM MGS MOC AFTER 2 MARS

YEARS IN THE MAPPING ORBIT” Lunar and Planetary Science XXXIV (2003)
1038.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1038.pdf

[174] <#_ftnref174> “Martian gullies discovered by Malin and Edgett [1]
are widely regarded as evidence of recent hillside erosion by liquid
water on Mars [2,3]. As reported earlier [3,4], Icelandic basaltic talus
slopes of hillsides contain gullies that include virtually exact
duplicates of

Martian gullies in terms of size, morphology, and placement with respect
to blocky outcrops. At the 2001 LPSC, Costard et al. [5] and Lee et al.
[6] also presented evidence of similar gullies in Greenland and Canada,

respectively.” William K. Hartmann et al “COMPARISON OF ICELANDIC AND
MARTIAN HILLSIDE GULLIES” Lunar and Planetary Science XXXIII (2002) 1904.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1904.pdf

[175] <#_ftnref175> “Global distribution of observed gully landforms”
diagram in “True Colors of Mars by Schmidt [2001] available online at

http://silver.neep.wisc.edu/~neep533/FALL2001/lecture19.pdf

http://www.harmakhis.org/history/gullies.jpg

[176] <#_ftnref176> “Evidence for Recent Liquid Water on Mars:
Gullies in Gorgonum Chaos” MGS MOC Release No. MOC2-236, 22 June
2000 available online at
http://www.msss.com/mars_images/moc/june2000/gorgonum/

[177] <#_ftnref177> “Mars Odyssey THEMIS Image: Gullies of Gorgonus
Chaos”  Mars Odyssey THEMIS
<http://www.spaceref.com/redirecth.html?id=0&url=http://themis.asu.edu/latest.html>
Tuesday, June 11, 2002 available online at
http://www.marstoday.com/viewsr.html?pid=5736

[178] <#_ftnref178> “Gorgonum Chaos: The Gorgonum Chaos basin is an
ancient, highly degraded 220-km diameter basin centered at about 37ºS
and 173ºW. The basin itself lacks a well-defined rim, and probably was
created through erosional integration of at least three impact basins
that were subsequently mantled by thick air fall deposits during or
prior to the earliest Noachian [1,2]. This basin, together with the
nearby Atlantis, Newton, and Ariadnes basins have been suggested to have
hosted deep lakes during part or most of the Noahian [3], and it has
been suggested that at least once the lakes were deep enough to have
formed an integrated basin overflowing to form Ma’adim Valles [4]. The
edges of these basins exhibit linear features that have been interpreted
as possible shorelines [3]. The present abstract focuses, however, on
bench-like features at the bottom of the Gorgonum Chaos basin that
appear to have been formed in association with a post- Noachian lake.
The Gorgonum Basin is shown in Figure 1, with the general location of
the post-Noachian lake outlined in cyan.” A. D. Howard and J. M. Moore
“THE CURIOUS SHORELINES OF GORGONUM CHAOS” Sixth International
Conference on Mars (2003) 3190.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3190.pdf

[179] <#_ftnref179> “Image analysis: A thorough analysis of the MOC
images coupled with a few simple climatic considerations suggest that
these gullies are not so young. The gullies are not deeply incised and
many of them are even filled up with detritus or dust-covered as can be
seen in the upper part of Fig. 1 thus showing that the generating
process acted only intermittently and was limited in time because no
aquifer recharge has been available after their first formation.” G.
Leone “GORGONUM CHAOS: ARE THE SEEPAGE-RUNOFF FEATURES REALLY RECENT?”
Lunar and Planetary Science XXXII (2001) 1649.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1649.pdf

[180] <#_ftnref180> “More speculative is our thinking on knob material
origin. We note that the knob fields largely occur within five adjacent
basins and within a restricted elevation range. Thus knob-material’s
restricted occurrence implies that it was emplaced in a (or as a) medium
that was limited in areal extent and possibly under a strong
gravity-control, such as a fluid. If this material is volcanic then its
susceptibility to modern wind erosion tends to disfavor emplacement by
molten lava flows but doesn’t entirely rule out a subaerial pyroclastic
density flow that didn’t significantly weld after emplacement. However,
this argument is weakened by the absence of evidence for volcanic
activity in the region. If the knob material was deposited in water,
then its composition could either be fine-grained clastic lacustrine
material or precipitates (evaporites). Such materials on Earth are
relatively unindurated. All

but one very small knob field occurs within and below the 1100 m
high-stand of a lake proposed by Irwin et al [1]. The single exception
is located in an isolated crater floor just SE of this putative lake and
at a few 100 m above its reported high-stand.” J. M. Moore and A. D.
Howard “ARIADNES-GORGONUM KNOB FIELDS OF NORTH-WESTERN TERRA SIRENUM,
MARS” Lunar and Planetary Science XXXIV (2003) 1402.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1402.pdf

[181] <#_ftnref181> “3. Gully Formation

[32] Recently, several groups have proposed that the young gullies
[Musselwhite et al., 2001; Hoffman, 2001, 2000b; Draper et al., 2000]
and many larger-scale features on Mars [Hoffman, 2000a; Hoffman et al.,
2001; Jo¨ns, 2001; Parsons, 2001] may have formed from slope collapse

related to the presence of subsurface liquid or solid CO2 and

subsequent CO2 vapor-supported flow.” Sarah T. Stewart and Francis Nimmo
“Surface runoff features on Mars:Testing the carbon dioxide formation
hypothesis” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. E9, 5069,
doi:10.1029/2000JE001465, 2002

http://bullard.esc.cam.ac.uk/~nimmo/paper16.pdf

[182] <#_ftnref182> “A clathrate mixture of CO2 and water ice, as long
as it's under a fair amount of pressure, can actually exist in a solid
form even if the ground is somewhat warmer than the melting point of
ordinary water ice. If such a buried clathrate deposit was suddenly
exposed by a landslide, the result would be a blast of liquid water --
squirted outward by the pressure of the vaporizing CO2 -- which could
pour down the slope for some distance before vaporizing in the thin
Martian air. [Since a rise in buried clathrate's temperature -- produced
by geothermal warmth or a change in Mars' long-term climate -- could
cause it to erupt in the same way, this is actually a variant on the
"soda-water fountain" theory I described in Part 1 of my report
<http://www.spacedaily.com/news/mars-water-science-00c1.html> -- except
that the eruption of soda water would be released by "uncapping the
bottle" through a landslide, rather than by through a temperature rise.]
The obvious problem here is that, for the water part of the released
clathrate to turn into liquid water rather than remaining a shower of
ice fragments, the eruption would have to occur where the ground
temperature was above 0 deg C. -- and the gullies are all in much colder
areas. A possible way out of this problem, however, would be for the
water part of the clathrate to be highly salty. As I mentioned in Part
1, some brines made out salts that are thought to be very common in
Mars' soil -- such as magnesium sulfate and calcium sulfate -- have
melting points dozens of degrees below that of pure water. And such
"briny clathrates" might exist in solid form in these cold regions, but
still be warm enough to turn into a short-lived torrent of liquid brine
when a landslide released the pressure on them. There is also, perhaps,
one more long-shot possibility. Carbon dioxide can't exist in liquid
form under the 1-bar pressure of Earth's atmosphere (thus, frozen CO2 is
known as "dry ice" because it sublimates directly from solid into gas).
However, liquid CO2 can exist if the pressure is more than 5 bars -- and
so there's a real possibility that large amounts of it may also exist
underground in some regions of Mars. If a landslide released such a
deposit, it just might remain liquid long enough to pour down a slope in
the same manner as liquid water before boiling into gas. This, however,
is unlikely -- Tanaka points out that such high-pressure liquid CO2
would explode into gas almost immediately on exposure to Mars'
near-vacuum, and he thinks that - unlike released liquid water - it
would have almost no time to pour down a slope in still-liquid form.
Carr, however, disagrees, and that this theory cannot be completely
ruled out.) Another problem is that for CO2 to be under enough pressure
to exist in liquid form, it must be much more deeply buried than a water
ice-CO2 clathrate -- under at least 30 meters of Martian soil and rock
-- and landslides big enough to suddenly unearth such a deposit would
have to be a lot larger. However, it's possible that a smaller landslide
could make the covering layer of rock and soil over such a deposit
shallow enough that the underlying pressure of the liquid CO2 could
cause it to burst out into the open.” Bruce Moomaw “The Case For
Outgassing” July 5, 2000 MARSDAILY.COM available online at
http://www.spacedaily.com/news/mars-water-science-00g2.html

[183] <#_ftnref183> Michael C. Malin and Kenneth S. Edgett “Evidence for
Recent Groundwater Seepage and Surface Runoff on Mars” 30 JUNE 2000 VOL
288 SCIENCE www.sciencemag.org <http://www.sciencemag.org/> available
online at

http://geoinfo.nmt.edu/penguins/pdfs/se260002330p.pdf

[184] <#_ftnref184> Malin Space Science Systems
<http://www.msss.com/>, MGS <http://mars.jpl.nasa.gov/mgs/>, JPL
<http://www.jpl.nasa.gov/>, NASA <http://www.nasa.gov/> “Newton
Crater: Evidence for Recent Water on Mars” Astronomy Picture of the
Day available online at

http://antwrp.gsfc.nasa.gov/apod/ap000626.html

[185] <#_ftnref185> “Evidence of drainage- The gullies in the CNewton
crater have been discussed by Malin and Edgett (2000) who performed
speculative scaling calculations to estimate the volume of water
involving the discharge event. They concluded that about 2.5x106 liters
of water were involved in each event, with nearly 100 channels active in
the crater, giving a total of nearly 0.25 km3 of water that must have
been discharged into the crater basin in a short period of time.” N. A.
Cabrol et al “PROLONGED PONDING EPISODE IN C-NEWTON CRATER IN RECENT
GEOLOGICAL TIMES ON MARS” Lunar and Planetary Science XXXII (2001) 1255.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1255.pdf

[186] <#_ftnref186> “… approach in the Tempe Terra region. Geologic
Setting: Tempe Terra is located on the northeastern flank of the Tharsis
volcano tectonic province. It is an ancient terrain of Noachian age
which has been cratered and heavily fractured. The western margin is
embayed by volcanic flows originating from Tharsis and Alba Patera while
the eastern margin is buried under probable alluvium from Kasei Valles
and other outflow channels.” B.W. Harrington et al “EXTENSION ACROSS
TEMPE TERRA, MARS FROM MOLA TOPOGRAPHIC MEASUREMENTS” 5^th Conference [1999]

http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6130.pdf

[187] <#_ftnref187> http://www.space4case.com/mars/mars5/mars131.html

[188] <#_ftnref188> “Introduction:  Numerous small volcanic edifices
have been previously identified in the Tempe Terra [1] and Ceraunius
Fossae regions of Mars [2, 3]. Low shield volcanoes  dominate 
Ceraunius  Fossae,  while Tempe  Terra  has  both  low  shields  and 
steeper, possibly explosively erupted cones [1]. These features are an
interesting example of plains volcanism, and several comparisons have
been made with terrestrial volcanic features. From  Viking  images, 
Hodges  and Moore [3]  used  crater  diameter/basal diameter (C/b)
ratios for  the Tempe  volcanoes [C/b  of 0.06-0.17]  to suggest  they 
may  be  similar  to  Mauna  Ulu  shield, Hawaii  and  low  shields  in 
the  Snake  River  Plain, Idaho.  Additional photoclinometric 
measurements made by  Davis and Tanaka  [4]  of  five  volcanoes in
Tempe  Terra indicated morphological  similarities  to terrestrial
cratered basaltic lava shields  and tuff  rings. Volcanoes in Ceraunius
Fossae  are less  well  studied, but  previous  work  suggested  they 
are  similar  to shields in Tempe Terra [3].” M. P. Wong et al “MOLA 
TOPOGRAPHY  OF  SMALL  VOLCANOES  IN  TEMPE  TERRA  AND  CERAUNIUS
FOSSAE,  MARS:  IMPLICATIONS  FOR  ERUPTIVE  STYLE” Lunar and Planetary
Science XXXII (2001) 1563.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1563.pdf

[189] <#_ftnref189> See Figure 1, E. Hauber et al “MORPHOLOGY AND
TOPOGRAPHY OF FRETTED TERRAIN AT THE DICHOTOMY BOUNDARY

IN TEMPE TERRA, MARS: GENERAL CHARACTERISTICS” Lunar and Planetary
Science XXXIII (2002) 1658.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1658.pdf

[190] <#_ftnref190> “Nirgal Vallis is an ancient valley thought for
nearly 3 decades to have been carved, in part, by running water at some
time far back in the Martian past. Today the valley is, like the rest of
Mars, quite dry. However, some of the high resolution Mars Global
Surveyor (MGS) Mars Orbiter Camera (MOC) images reveal small gullies on
the walls of this valley system. An example is shown here (above, left),
in which more than 14 channels nearly 1 kilometer (0.6 miles) long run
down the south-facing slope of the Nirgal Vallis wall. Each narrow
channel starts at about the same position below the top of the valley
wall, indicating that there is a layer along which a liquid--most
likely, water--has percolated until it reached the cliff, then ran down
hill to form the channels and the fan-shaped aprons at the bottom of the
slope. Some of the apron deposits seem to cover the dunes on the floor
of the valley (lower 1/3 of the image), suggesting that the channels and
aprons formed more recently than the dunes. The fact that neither the
dunes nor the aprons and channels have impact craters on them suggests
that these features are all geologically young, meaning a few million
years at most, a few days or weeks at least.”

“Evidence for Recent Liquid Water on Mars: South-facing Walls of
Nirgal Vallis” MGS MOC Release No. MOC2-240, 22 June 2000”
http://www.msss.com/mars_images/moc/june2000/nirgal/

[191] <#_ftnref191> NASA/JPL/Arizona State University “Nirgal
Vallis (Released 27 March 2002)”
http://themis.la.asu.edu/zoom-20020327a.html

[192] <#_ftnref192> J. R. Zimbelman “DECAMETER-SCALE RIPPLE-LIKE
FEATURES IN NIRGAL VALLIS AS REVEALED IN THEMIS

AND MOC IMAGING DATA” Sixth International Conference on Mars (2003) 3028.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3028.pdf

[193] <#_ftnref193> “Small valley networks on Mars: Two alternative
modes of formation for the small valley networks on Mars are generally
considered: a) the valleys resulted from surface runoff following
precipitation or b) they

resulted from the release of groundwater, with or without the
involvement of hydrothermalism [e.g., 2]. In some instances, a case for
the possible role of sapping has been made (such valleys would belong to

“b”). For instance, Lee et al. [1] have reported ground ice sapping
valleys within the distinctive impact breccia formation at Haughton
crater, Devon Island, Canada, that are possible analogs to martian small

valleys such as Nirgal Vallis.

…

We interpret the Devon valley networks to be glacial meltwater channel
networks: they formed as a result of the decay and retreat of an ice
cover, possibly with intervals of glacial reoccupation. The proposed

mode of formation is supported by our observation that similar networks
can been seen actively emerging at the margin of the ice cap in the
eastern part of Devon Island. Both subglacial and ice-marginal streams,
and in some instances supraglacial streams and their icemarginal

falls, were seen to present significant discharges and contribute to
valley formation at several sites along the receding edge of the cap.
The interpretation of valley networks on Devon Island as meltwater
channel networks is consistent with the island’s overall landscape of
glacial selective linear erosion, which suggests extensive former
glacial occupation (mostly static ice) [5].” Pascal Lee and James W.
Rice Jnr. “SMALL VALLEYS NETWORKS ON MARS: THE GLACIAL MELTWATER CHANNEL
NETWORKS OF DEVON ISLAND, NUNAVUT TERRITORY, ARCTIC CANADA, AS POSSIBLE
ANALOGS” Fifth International Conference on Mars 6237.pdf
http://www.lpi.usra.edu/meetings/5thMars99/pdf/6237.pdf

[194] <#_ftnref194> “Autumn Afternoon in Hale Crater”MGS MOC Release
No. MOC2-257, 17 November 2000
http://www.msss.com/mars_images/moc/nov_00_hale/

[195] <#_ftnref195> Figure 6 Nature  Insight: Review article Hale Crater
http://www.nature.com/nature/journal/v412/n6843/fig_tab/412228a0_F6.html

[196] <#_ftnref196> “Interpretations: I interpret the viscous-flow
features as ice, glaciers, and rock glaciers derived from seepage and
eroded valley wall material associated with gully and alcove formation
[1 and 2]. I suggest that ice formation and accumulation have occurred
on the NW wall of the valley under conditions of relatively low
sublimation due to reduced insolation on pole-facing slopes [3]. Ice and
ice-rich debris built up over time and began to flow under the influence
of gravity in the form of glaciers and rock glaciers. These eventually
reached the floor of the valley and continued to flow until areas of
higher insolation were encountered. In these areas, the sublimation
rates were high enough to ablate the glaciers to the point that they
could advance no further.”

J. D. Arfstrom “UPPER DAO VALLIS: A BASIN DOMINATED BY ICE-RICH VISCOUS
MATERIALS” Lunar and Planetary Science XXXIV (2003) 1208.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1208.pdf

[197] <#_ftnref197> “Observations: The ice formations on the slopes of
Dao Vallis appear to be tributaries of an even more extensive ice
formation on the floor of the valley (Figure 1). The ice formations of
the slopes merge with the ice formation at the bottom of Dao Vallis in a
way that suggests mutual flow, closely resembling the way terrestrial
tributary glaciers merge with main valley glaciers (Figure 2). The ice
formations on the

slopes and floor of Dao Vallis possess distinct structural morphologies
that are characteristic of terrestrial alpine glaciers (Figure 3).”

J. D. Arfstrom “PROPOSED MARTIAN GLACIERS OF RECENT AGE AND A MODEL OF
THEIR FORMATION” Lunar and Planetary Science XXXIII (2002) 1092.pdf

http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1092.pdf

[198] <#_ftnref198> http://www.harmakhis.org/history/gullies.jpg

[199] <#_ftnref199> “Cosmetic alterations A dirty ice sheet that once
extended over Mars’s mid-latitudes would explain several

enigmatic features there. Some of these have puzzled planetary
scientists ever since the two Viking orbiters returned images in the
late 1970s that looked for all the world like ice-related surface
features on Earth. Most suggestive of ice, perhaps, were places where
the surface seemed to be sloughing off the land and oozing downhill.
Generically termed “viscous flow features,” they looked like the work of
Earth’s rock glaciers, streams of flowing rock-laden ice. Many more have
since turned up in close association with the dissected mantling spotted
by Mars Global Surveyor. In the 13,000 MOC images they have inspected,
Milliken and his Brown colleagues reported at the workshop, viscous flow
features are restricted to the same 30° to 60° mid-latitude bands as the
dissected mantling. The flows peak in abundance at the same 40° latitude
as the dissected mantling.

Furthermore, the mysterious gullies—where liquid water seems to have
flowed down steep slopes in the recent past—follow the same latitudinal
distribution as viscous flow features and dissected terrain; they even 
tend to cluster in the same three or four places as the viscous flow
features do. The currently favored explanation for gullies is that
lingering patches of dirty snow melted there (Science, 28 February, p.
1294). Taken together, the Brown researchers say, these features could
be explained by the warming of an ice-rich mantling. That could have
produced meltwater that formed gullies, ice softening that gave rise to
viscous flow, and ice loss through sublimation that weakened the
mantling and allowed dissection. “That’s consistent with what I’ve seen”
in images, says planetary geologist James Zimbleman of the Smithsonian
Institution’s National Air and Space Museum in Washington, D.C. “I’d
call it a working hypothesis.” “Iceball mars?” 11 APRIL 2003 VOL 300
SCIENCE www.sciencemag.org <http://www.sciencemag.org/> available online at

http://www.planetary.brown.edu/planetary/international/write_up.pdf

[200] <#_ftnref200> “At a press conference and in a paper published
online by Nature on Wednesday, planetary scientist Phil Christensen of
Arizona State University proposed a new idea to explain the creation of
the martian gullies. He suggests they could have been carved by water
melting from snow banks.” Vanessa Thomas “Snow May Have Carved Martian
Gullies” Astronomy.com available online at

http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/215vpcsq.asp

[201] <#_ftnref201> “4. Occurrence of levees: Levees on each sides of
the channels are typical of a particular kind of flows

with a yield strength [12]. The yield strength corresponds to the
minimal shear strength the material needs to reach before to flow. They
are typically associated to flows containing 50 to 90% of solid
particles (silt to pebble size) [12]. In Izoard, levees are 2 m high for
a 10 m large channel, a size comparable to gullies observed on several
MOC images. The existence of levees implies the incorporation of
meltwater in the debris over a significant thickness of material. This
is possible only if thawing of the ground occurs over a significant
thickness (several tens of cm), on the contrary to the model of snowmelt
proposed by Christensen [5] under present conditions. The ratio of water
to sediment of 10:1 proposed by Christensen (so 10% of rock) is also not
in the range of debris flows with levees which are characterized by a
proportion of more than 50% of rock [12]. Nevertheless, if existing
during high obliquity periods, the presence of snowpacks would favor the
process of debris flows because snowmelt can efficiently fill the
porosity of debris as observed in cold regions in Greenland [4] or North
Canada [7].” N. Mangold et al “FORMATION OF GULLIES ON MARS: WHAT DO WE
LEARN FROM EARTH?” Sixth International Conference on Mars (2003) 3048.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3048.pdf

[202] <#_ftnref202> “Now UA researchers propose an alternative
explanation involving carbon dioxide erosion. They point to several
reasons why CO2 is a better candidate than water in gully formation. One
reason is that most gullies are found in the southern highlands, the
oldest and coldest part of the planet, a place where liquid water is
least likely to be stable.

"That's high altitude in a region of low geological activity. It is
difficult to invoke some hydrothermal action there," Musselwhite said.
"The surface is old but the gullies are new."

Another reason is that the southern hemisphere has more extreme
temperature variations throughout the year than does the northern
hemisphere, a result of the fact that Mars is closer to the sun during
southern summer and farther away during southern winter, Musselwhite said.

The gullies are generally on pole-facing slopes where they receive very
little or no sunlight for most of the year.

However, Musselwhite said, the most compelling fact is that gullies
always start about 100 meters below the top of the cliff. At that depth,
the pressure of the rock overhead is just enough for liquid CO2 to be
stable, if the temperature is low enough.” Agnieszka Przychodzen
*“*Exotic CO2 Process May Have Carved Martian Gullies” MARSDAILY
<http://www.marsdaily.com/>April 2, 2001 available online at
http://www.spacedaily.com/news/mars-water-science-01f.html

[203] <#_ftnref203> See Figure 3

“3. The Role of Water

[11] The observed geographic (Figure 4), temporal (Figure 5), and
azimuthal (Figure 6) correlations provide evidence for a connection
between slope streaks and a surface temperature near the triple point of
water, suggesting that the formation of streaks involves a phase
transition of water. For instance, melting could provide lubrication of
avalanches, or mass movements could be triggered by sublimation at the
solid-gas transition. The analysis presented does not pinpoint a
specific mechanism for slope streak formation, and hence we do not
elaborate on any particular one, but consider the potential role of
water generically.

(See also Ferris et al. [2002].) While alternative explanations not
involving water, such as patterns in atmospheric dust transport, can be
envisioned, the observations are simply accounted for if water plays a
role, either in triggering the mass movements or in controlling dust
deposition.”  Norbert Schorghofer et al “Slope streaks on Mars:
Correlations with surface properties and the potential role of water”
GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 23, 2126,
doi:10.1029/2002GL015889, 2002 available online at

http://www.gps.caltech.edu/~oa/publications/schorghofer2002_grl.pdf

[204] <#_ftnref204> “When examined in detail individually and as a group
it appears that the seep features have far more characteristics
associated with liquid flows than with flows of dry dust or slurries.
The equatorial location of the seepages, clustering in the Tharsis
region (and 180 degrees away north of the Hellas Basin) plus physical
flow attributes, indicate that water (or possibly some other liquid) may
be involved in their genesis. As we have demonstrated, these features
are currently being formed on the Martian surface. These circumstances
together imply that it is highly likely that water is now present on the
surface of Mars.” Efrain Palermo, Jill England and Harry Moore “A Study of

Mars Global Surveyor (MGS)Mars Orbital Camera (MOC) Images

Showing Probable Water Seepages. Are They Dust Slides as NASA Claims or
Proof of Water on Mars?” available online at

http://www.eskimo.com/~jill/seeps_paper.pdf

[205] <#_ftnref205> See Figure 3 R. Sullivan et al “MASS-WASTING SLOPE
STREAKS IMAGED BY THE MARS ORBITER CAMERA” Lunar and Planetary Science
XXXI 1911.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1911.pdf

[206] <#_ftnref206> “Summary. We conclude that dark streak formation on
Martian slopes is fundamentally similar to small mass-movements that
have occurred on debris-covered steep slopes elsewhere on Mars;
distinctive dark streak features result where small mass-movements occur
in the presence of a thin, potentially mobile dust mantle. They cannot
be easily interpreted as a dark fluid stain or float moving downslope
from a point source.”

R. Sullivan et al “MASS-MOVEMENT CONSIDERATIONS FOR DARK SLOPE STREAKS
IMAGED BY THE MARS ORBITER CAMERA “ Lunar and Planetary Science XXX
1809.pdf

http://www.lpi.usra.edu/meetings/LPSC99/pdf/1809.pdf

[207] <#_ftnref207> http://ida.wr.usgs.gov/html/ab1020/ab102003.html

[208] <#_ftnref208> http://www.harmakhis.org/ab102003dspires.jpg.htm

[209] <#_ftnref209>
http://www.msss.com/moc_gallery/m19_m23/images/M23/M2300332.html

[210] <#_ftnref210>
http://www.msss.com/moc_gallery/e07_e12/images/E11/E1103683.html

[211] <#_ftnref211> “Crystalline hematite has been mapped over an area
in Sinus Meridiani approximately 500 km in longitude extending
approximately 200 km in latitude [3]. The extent of this deposit very
closely matches the geomorphic boundary of a smooth, layered, friable
unit that is interpreted to be sedimentary sedimentary in origin [3, 9].
This material may be the uppermost surface in the region, indicating that it

might be a later-stage sedimentary unit, or alternatively a layered
portion of the heavily cratered plains units. A second accumulation of
hematite approximately 60 x 60 km in size is observed in Aram Chaos (2°
N, 21° W). This site is also associated with layered materials and a
water-rich environment.” P.R. Christensen et al “THE DISTRIBUTION OF
CRYSTALLINE HEMATITE ON MARS FROM THE THERMAL EMISSION

SPECTROMETER: EVIDENCE FOR LIQUID WATER” Lunar and Planetary Science
XXXI 1627.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1627.pdf

[212] <#_ftnref212> “Figure 4. Crater count diagram and isochrons for
the Terra Meridiani hematite-rich area. Filled symbols show the
population of "fossil craters" lying near the saturation equilibrium
limit (upper straight line), indicating a very ancient surface. Open
symbols show the fresh, recent craters created since the modern surface
formed, indicating that the area has been exposed for as little as a few
million years. Our interpretation is that an ancient (paleolake bed?)
was covered by sediments and exhumed only a few million years ago.”
Melissa D. Lane et al “UPDATE ON STUDIES OF THE MARTIAN HEMATITE-RICH
AREAS” Lunar and Planetary Science XXXII (2001) 1984.pdf

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1984.pdf

[213] <#_ftnref213> “Mineral abundance maps (Fig. 5) show basaltic
lithologies for much of the VM interior, in the form of high- and low-Ca
pyroxenes (up to 24% total) and plagioclase minerals (up to 28%) in
layered deposits in the walls and interior, as well as in dark materials
at the base of canyon walls. Note that the presence of surface dust in
parts of Ophir and east Candor Chasmata appears to decrease the apparent
abundance of minerals in these areas. The distribution of gray hematite
agrees well with previous results [18], but we see only (~8%) a small
enrichment of red hematite in the possible hydrothermal site in west
Candor [14] (Fig. 6).” L.R. Gaddis et al “MINERAL MAPPING IN VALLES
MARINERIS, MARS: A NEW APPROACH TO SPECTRAL DEMIXING OF TES DATA” Lunar
and Planetary Science XXXIV (2003) 1956.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1956.pdf

[214] <#_ftnref214> “Our observations of hematite in the VM are similar
to those seen by Christensen et al., [37].” F. S. Anderson et al
“MINERALOGY OF THE VALLES MARINERIS FROM TES AND THEMIS” Sixth
International Conference on Mars (2003) 3280.pdf

http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3280.pdf

[215] <#_ftnref215> “Aram Chaos is a 280 km diameter crater centered at
2.5N, 338.5 E. Like other nearby craters, it has been filled with a
large amount of material since its formation [2]. It is connected to the
Ares Vallis

outflow channel by a small, 15 km wide channel that flowed outward, from
Aram Chaos to Ares Vallis. The association of Aram Chaos with the
outflow channels, as well as its obvious basin morphology,

indicates a possible connection to past surface and subsurface water in
the region.” Timothy D. Glotch and Philip R. Christensen “The Geology of
Aram Chaos” Lunar and Planetary Science XXXIV (2003) 2046.pdf

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/2046.pdf

[216] <#_ftnref216> http://www.harmakhis.org/paper/dunes/dunes.htm

[217] <#_ftnref217> http://www.harmakhis.org/paper/dunes/dunesdata.htm

[218] <#_ftnref218> “There are a number of reasons to proceed with
numerical modeling of sand transport at this time. Most importantly, the
wind regime near the surface is strongly influenced by topography, and
the first accurate map of global topography from MGS MOLA has only
recently become available. Mars GCM’s now appear to adequately simulate
the circulations during dust storm periods, which produce some of the
strongest surface winds [8]. Finally, Mars GCM’s now have the
flexibility to examine wind regimes from different epochs. We have used
surface wind output from the GDFL Mars GCM to build a global sand
transport model for Mars. Several parameters have the same values used
by Anderson et al. [1] in order to directly compare the Ames GCM output
with that of the GDFL GCM. We compare the resulting sand distribution
with the known sand dunes on the Martian surface. We also compare our
results with those of Anderson

et al. [1]. The RDP/DP is also calculated along with the sand transport,
and these values are compared with known dune forms and orientations as
well as to the results found by Lee and Thomas [7] with the Ames GCM.”
L. K. Fenton and M. I. Richardson “GLOBAL MARTIAN SAND TRANSPORT AS
PREDICTED BY THE GDFL MARS GCM” Lunar and Planetary Science XXXI 2072.pdf

http://www.lpi.usra.edu/meetings/lpsc2000/pdf/2072.pdf

[219] <#_ftnref219>
http://www.harmakhis.org/paper/newsouth/spoledunes/spoledunesdata.htm

[220] <#_ftnref220> “Sand dunes are representative of these types of
landforms. With nearly three years of high resolution observations of
relatively small dunes, no evidence whatsoever has been found to support
the contention that any dunes on Mars are presently mobile. Yet their
dune crests appear to be quite sharp (inactive dunes still shed sand
from their

crests and become rounded with age), and subtle markings on their slip
faces suggest that a small amount of avalanche sand may move under the
added weight of winter snow. Occasionally, dunes exhibit striations that
suggest that their surfaces may be cemented or crusted, but for the most
part their inactivity in the presence of winds likely to be able to move
sand (we see dust-devil tracks on some dunes) suggests that their
inactivity may be related to some environmental factor, such as the
absence of locally sustained winds.” M. Malin and B. A. Cantor “MARS
ORBITER CAMERA CLIMATE OBSERVATIONS” available online at
http://www-mars.lmd.jussieu.fr/granada2003/abstract/malin.pdf

[221] <#_ftnref221> http://www.harmakhis.org/paper/layers/layers.htm

[222] <#_ftnref222> http://www.harmakhis.org/paper/layers/layersdata.htm

[223] <#_ftnref223> “Exposures of layered materials in western Candor
Chasma illustrates yet another incongruent relationship: these layered
outcrops display very few impact craters on their surface. Indeed, they
show crater densities two to three orders of magnitude lower than those
seen within the summit caldera of Arsia Mons (Figure 3). Since the
evidence is very good that these materials are ancient and being
exhumed, the absence of craters means that the layers have been recently
exhumed, or that their surfaces have been recently eroded (if the Arsia
Mons caldera is of the

order of hundreds of millions of years old, then the surfaces in Candor
are only hundreds of thousands to millions of years old, and in cases
where there are no craters at all, even younger). We see no evidence of
the process that has exposed these materials, and no evidence for where
the materials have gone. There is certainly nothing acting today that
could create what we see. This landscape, too, is not representative of
the present-day suite of processes.” Ibid. available online at

http://www-mars.lmd.jussieu.fr/granada2003/abstract/malin.pdf

[224] <#_ftnref224> “Two basic processes are portrayed: deposition of
sediment as dust settling out of the atmosphere, and deposition in
bodies of water such as crater lakes and shallow seas.

The chief source for sediment in both cases may be a combination of
materials produced by explosive volcanism and meteorite impact, as well
as weathering and erosion, researchers said.

Malin and Kenneth Edgett have suggested that the some of the layers may
have formed underwater in lakes or perhaps shallow seas inside craters.

If the sediment fell from the air, then some recurring phenomenon would
have had to create thin layers of regular thickness and properties --
the type of deposition that occurs in bodies of water.

Malin and Edgett explained how deposition from the air might have
occurred. The atmosphere's pressure might have varied on a regular basis
from something that is hundreds of times thicker than it is at present
to something that is perhaps only tens of times (or less) thicker than
it is today. As the atmospheric pressure went up, it could have carried
more dust to be deposited; as it went down, there would have been less.

It is also possible, the researchers say, that the layers were created
by a combination of deposition from the air and from water.

"Ultimately, geologists will have to go to Mars," Malin said, "to
investigate the changes in ancient Martian environments recorded in
these rocks."

Jack Farmer, director of the astrobiology program at Arizona State
University, said standing water is the most likely explanation for the
layering.

"This truly is exciting stuff," Farmer told SPACE.com. "If true, it
indicates that water-lain sediments could be much more widespread than
we thought previously." Senior Science Writer  “MORE IMAGES: Martian
Sediment Layers Explained” 05 December 2000 available online at
http://www.space.com/scienceastronomy/solarsystem/mars_sediment_pics_001205.html

[225] <#_ftnref225> Science at NASA “Layers of Mars” available online at

http://science.nasa.gov/headlines/y2001/ast23jan_1.htm

[226] <#_ftnref226> “HOUSTON,TEXAS—Planetary scientists poring over the
latest data returned by Mars orbiting spacecraft have reached a
startling conclusion: Half the Red Planet appears to have been encrusted
with ice in the relatively recent past. A layer of dirty ice still
covers Mars poleward of latitudes that, on Earth, would encompass
Anchorage, Moscow, and South America’s tip. But several lines of
evidence suggest that, within the past million years or so, a
now-vanished ice layer cloaked Mars down to the latitudes of Buenos
Aires, New Orleans, and Baghdad. This icy coating would not have been
the first to cover large areas of Mars, according to new climate
modeling reported last month at a workshop here.* Mars has a tendency to
wobble back and forth on its axis, and the new modeling suggests that
this instability would have triggered a succession of ice ages
throughout the planet’s history. The tilting would have shifted polar
climes to lower latitudes, vaporizing the polar ice caps and layering
dirty ice toward the equator. That would help explain much geology that
has puzzled researchers for as long as 30 years: swaths of “softened”
martian terrain that look like they’re made of ice cream scooped on a
hot day, slopes that ooze like wet paint dripping down a wall, and even
the enigmatic gullies where water seems to have flowed on a frozen
planet. More speculatively—and farther back in Mars history— extreme
tilting of the planet may have repeatedly driven ice sheets right down
to the equator. If so, that ice is gone now, but the dust left behind
could have formed the mysterious layered sediments of the equatorial
region.” “Iceball Mars?” 11 APRIL 2003 VOL 300 SCIENCE
www.sciencemag.org <http://www.sciencemag.org/> available online at

http://www.planetary.brown.edu/planetary/international/write_up.pdf

[227] <#_ftnref227> “Recent research has confirmed the observation that
extensive areas of Mars are dominated by layered terrain. Layers exist
everywhere - even within craters. This poses two main problems,
depending on the interpretation of the origin of the layers.

If the layers are sedimentary, then it implies an active early
sedimentary history for Mars, involving a far stronger hydrological
cycle than we have evidence for. If early Mars were this active, then
all the early craters should have been wiped away, yet they are largely
unaffected. In addition, layering exists within many unbroken craters,
without sign of an entry or exit channel. It is as if the layers had
fallen from the skies.

If the layers are lavas, then it implies a much greater early volcanic
history than we see evidence for. Again, many of the large early craters
should have been destroyed or buried, and we should see evidence for
many more volcanic vents and fissures than we do in fact see. In one
way, the volcanic model can explain the layers in enclosed craters.
Massive volcanic eruptions could have formed ash clouds that rained down
into the craters, yet we don't see the vents.

Here are the seeds of yet another Mars paradox
<http://www.earthsci.unimelb.edu.au/mars/Paradox_Oth.html>. The evidence
is internally contradictory. We see layers, yet no sign of the processes
that caused them or the likely side effects of those processes.” N.
Hoffman “Origin of Layering on Mars” available online at
http://www.earthsci.unimelb.edu.au/mars/Layer.html

[228] <#_ftnref228> “Analysing the spectra from the ten different bands
of infrared light the instrument can detect, the THEMIS team has begun
to identify specific mineral deposits, including a significant layer of
the mineral olivine near the bottom of a four-and-a-half kilometer deep
canyon known as Ganges Chasma. Olivine, Christensen notes, is
significant because it decomposes rapidly in the presence of
water. "This gives us an interesting perspective of water on Mars" he
says. "There can't have been much water – ever – in this place. If there
was groundwater present when it was deep within the surface, the olivine
would have disappeared. And since the canyon has opened up, if there had
ever been water at the surface it would be gone too. This is a very dry
place, because it's been exposed for hundreds of millions of years. We
know that some places on Mars have water, but here we see that some
really don't." “Olivine points to dry Mars”  June 6, 2003 available
online at http://www.geolsoc.org.uk/template.cfm?name=THEMIS

[229] <#_ftnref229> “However, there are a few places exhibiting
large regional exposures. The largest is in north Terra Meridiani
(8°N–5°S, 8°W–9°E). These layers are laterally continuous over
hundreds of kilometers. Some can be traced west and northwestward
until they disappear amid craters of ancient, heavily cratered
terrain. The layers are interbedded with craters that also contain
layers. Beds are nearly horizontal and form cliffs. In some places
they form buttes and mesas of a scale similar to those of Monument
Valley in Arizona/Utah. The bedding properties, buttes, and cliffs
indicate the material is indurated and is sedimentary. Observations
from the Viking Infrared Thermal Mapper and MGS Thermal Emission
Spectrometer suggest the outcrop surfaces have effective particle
sizes of very coarse sand (or coarser); this might indicate that a
thin regolith has developed on the outcrops. A Phobos 2 Termoskan
image shows that different layers (or groups of layers) exhibit
different thermal properties, indicating differing physical
properties of the overlying, thin regolith. The Termoskan and MOC
images, together, also show that eolian mantles obscure
formerly-exposed outcrops in adjacent intercrater plains. True
lithostratigraphic geologic mapping of the layers is underway.
Determination of processes that exposed the layers is difficult.
There are no streambeds to indicate fluvial, nor yardangs to
indicate eolian, erosion. Likewise, the depositional environments
and sediment provenance cannot be uniquely determined. Colleagues
have proposed a tremendous range of origins, but all are
speculative, at best: the geology and relation to surrounding
terrain is very complex.”  EDGETT, Kenneth S
<mailto:edgett at msss.com> “SEDIMENTARY ROCK OUTCROPS OF NORTHERN
TERRA MERIDIANI, MARS”  Paper No. 26-7 2002 Denver Annual Meeting
(October 27-30, 2002)
Denver, CO available online at
http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_42548.htm

[230] <#_ftnref230> Jenkins, Gregory S. 2001 “High-obliquity
simulations for the Archean Earth: Implications for climatic
conditions on early Mars” Journal of Geophysical Research - Planets
- Vol. 106, No. E12 http://www.agu.org/pubs/toc/je/old/je106_12.html

[231] <#_ftnref231> For a good novel based on life surviving these
impacts that may have killed the dinosaurs there is “Evolution” by
Steven Baxter.