http://SaturnianCosmology.Org/ mirrored file For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== You are not entitled to access the full text of this document Earth's glacial record : Deynoux, M. Miller, J.M.G., Domack, E.W., Eyles, N., Fairchild, I.J. and Young, G.M. (eds), 1994. Cambridge University Press, Cambridge, U.K. hardcover, £60.00, ISBN 0-521-42022-9 XVII + 266 pp Quaternary Science Reviews, Volume 14, Issue 10, 1995, Pages 1045-1046 J. Menzies Purchase PDF (317 K) Cyclic Aggradation and Downcutting, Fluvial Response to... Quaternary Research Close You are not entitled to access the full text of this document Cyclic Aggradation and Downcutting, Fluvial Response to Volcanic Activity, and Calibration of Soil-Carbonate Stages in the Western Grand Canyon, Arizona Quaternary Research, Volume 53, Issue 1, January 2000, Pages 23-33 Ivo Lucchitta, Garniss H. Curtis, Marie E. Davis, Sidney W. Davis, Brent Turrin Abstract In the western Grand Canyon, fluvial terraces and pediment surfaces, both associated with a Pleistocene basalt flow, document Quaternary aggradation and downcutting by the Colorado River, illuminate the river's response to overload and the end of overload, and allow calibration of soil-carbonate stages and determination of downcutting rates. Four downcutting-aggradation cycles are present. Each begins with erosion of older deposits to form a new river channel in which a characteristic suite of deposits is laid down. The current cycle (I) started not, vert, similar 700 yr B.P. The oldest (IV) includes the 603,000 ± 8000 to 524,000 ± 7000 yr Black Ledge basalt flow, emplaced when the river channel was not, vert, similar 30 m higher than it is now. The flow is overlain by basalt-cobble gravel and basalt sand. Soils reach the stage V level of carbonate development. Calibrated ages for soil stages are Stage V, not, vert, similar 525,000 yr; stage IV, <525,000 yr, >=250,000 yr; stage III, <250,000 yr, >=100,000 yr. The monolithologic basalt sand beds represent overloading by volcanic ash produced by an eruption 30-50 km upstream. The basalt-cobble beds signal breaching and rapid destruction of lava dams and erosion of flows. These deposits show that the Colorado River responds to overload by aggrading vigorously during the overload and then downcutting equally vigorously when the overload ends. The overall downcutting rate for the interval studied is 1.6 cm/1000 yr, much lower than rates upstream. The current downcutting rate, 11-14 m/1000 yr, likely is a response both to the end of late Pleistocene and early Holocene overload and to the reduction of sediment supply caused by Glen Canyon Dam. You are not entitled to access the full text of this document A Karst Connection model for Grand Canyon, Arizona, USA Geomorphology, Volume 95, Issues 3-4, 15 March 2008, Pages 316-334 C.A. Hill, N. Eberz, R.H. Buecher Abstract A new model for the connection of the eastern and western Grand Canyon is proposed that involves westward flow of Redwall karst aquifer water under the Kaibab arch along the steepest hydraulic gradient to discharge at a structural low in a headward-eroding protowestern Grand Canyon. A karst-aquifer hydrological connection was first established between the eastern and western Grand Canyon, then collapse, incision, and headward erosion of the canyon followed this subterranean route. This proposed model is based on what is happening today on the northern Marble Platform where the Redwall-Muav aquifer is still intact. The three sinkhole/caves Ah Hol Sah, Indian Pit, and Black Abyss provide vertical flow routes down to the Redwall karst aquifer, joining water discharging from the Kaiparowits hydrologic basin to the Colorado River along the Fence Springs system. Projecting this process back in time and spatially southward, we propose that at around 6 Ma a sinkhole or sinkholes existed at the confluence of the Colorado River with the Little Colorado River. Little Colorado River water, then flowing northward to an interior lake basin ("Glen Lake") in southern Utah, became pirated down this sinkhole(s), thus causing a reversal of drainage (barbed tributaries) in Marble Canyon. Headward erosion then proceeded up Marble and Little Colorado Canyons from the collapsing sinkhole, with Marble Canyon incision breaching Glen Lake at around 5.5 Ma. This effected the "final connection" and total integration of the Colorado River from Colorado to the Gulf of California. Purchase PDF (2692 K) Influence of topographic complexity on solar insolation... Ecological Modelling Close You are not entitled to access the full text of this document Influence of topographic complexity on solar insolation estimates for the Colorado River, Grand Canyon, AZ Ecological Modelling, Volume 183, Issues 2-3, 25 April 2005, Pages 157-172 Michael D. Yard, Glenn E. Bennett, Steve N. Mietz, Lewis G. Coggins Jr., Lawrence E. Stevens, Susan Hueftle, Dean W. Blinn Abstract Rugged topography along the Colorado River in Glen and Grand Canyons, exemplifies features common to canyon-bound streams and rivers of the arid southwest. Physical relief influences regulated river systems, especially those that are altered, and have become partially reliant on aquatic primary production. We measured and modeled instantaneous solar flux in a topographically complex environment to determine where differences in daily, seasonal and annual solar insolation occurred in this river system. At a system-wide scale, topographic complexity generates a spatial and temporal mosaic of varying solar insolation. This solar variation is a predictable consequence of channel orientation, geomorphology, elevation angles and viewshed. Modeled estimates for clear conditions corresponded closely with observed measurements for both instantaneous photosynthetic photon flux density (PPFD: µmol m^ -2 s^ -1) and daily insolation levels (relative error 2.3%, CI ±0.45, S.D. 0.3, n = 29,813). Mean annual daily insolation levels system-wide were estimated to be 36 mol m^ -2 d^ -1 (17.5 S.D.), and seasonally varied on average from 13.4-57.4 mol m^ -2 d^ -1, for winter and summer, respectively. In comparison to identical areas lacking topographic effect (idealized plane), mean daily insolation levels were reduced by 22% during summer, and as much as 53% during winter. Depending on outlying topography, canyon bound regions having east-west (EW) orientations had higher seasonal variation, averaging from 8.1 to 61.4 mol m^ -2 d^ -1, for winter and summer, respectively. For EW orientations, 70% of mid-channel sites were obscured from direct incidence during part of the year; and of these sites, average diffuse light conditions persisted for 19.3% of the year (70.5 days), and extended upwards to 194 days. This predictive model has provided an initial quantitative step to estimate and determine the importance of autotrophic production for this ecosystem, as well as a broader application for other canyon systems. Purchase PDF (554 K) Contrasting types of chromium-spinel peridotite xenolit... Earth and Planetary Science Letters Close You are not entitled to access the full text of this document Contrasting types of chromium-spinel peridotite xenoliths in basanitic lavas, western Grand Canyon, Arizona Earth and Planetary Science Letters, Volume 23, Issue 2, September 1974, Pages 229-237 M.G. Best Abstract Several hundred xenoliths of Cr-diopside-spinel peridotite from basanitic lavas in the western Grand Canyon along the eastern margin of the Basin and Range Province can be grouped into essentially three distinct textural categories with correlative contrasts in mineral composition. At least two of these textures seem unique to this locality. Xenoliths display varying degrees of depletion in basaltic constituents and last equilibrated between 900 and 1000°C. A few contain coarse exsolution intergrowths of diopside and enstatite whose reconstructed composition has about 15 wt.% CaO corresponding to an original temperature of crystallization of approximately 1400°C. The genetic relation between the three types -- if such exists -- is uncertain, but overall they indicate a vertically inhomogeneous upper mantle. The variety of textures found worldwide in mantle-derived Cr-spinel peridotite xenoliths of more or less equivalent composition suggests varied and probably complexly superposed histories. Purchase PDF (1365 K) View More Related Articles