http://SaturnianCosmology.Org/ mirrored file For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== Estimates of Global Expansion Plate tectonic theory assumes an equivalence between global spreading and subduction rates. For every square kilometer of new crust created by seafloor spreading, an equal amount of old crust must be consumed by subduction. However, if the rate of subduction is less than the spreading rate, then a net increase in surface area would result and the Earth would expand.^1 Though currently out-of-favor among geoscientists, the Earth expansion hypothesis has a long and venerable history. It was first proposed in the 1920s and 30s, by O.C. Hilgenberg and others. More recently, S.W. Carey^2 , L.C. King^3 , and H.G. Owen^4 have been the most vigorous advocates of expansion. Their work deserves much wider recognition than it has received. Although I have been greatly influenced by their ideas, consideration of the possible effects of gravity variations on dinosaur evolution, discussed herein, leads to somewhat different conclusions regarding the extent and rate of post-Pangean Earth expansion as well as the possibility of Late Mesozoic contraction. I am fully aware that these conclusions conflict with most Earth expansion models, not to mention the reigning plate tectonic paradigm. The paleontological evidence discussed herein suggests that gravity during the Late Permian and Early Triassic was 1 g or slightly higher, as indicated by the robust morphology of the mammal-like reptiles. Assuming constant mass, this indicates an Earth of current dimensions, or somewhat smaller, during the Permo-Triassic. Using the thecodonts and dinosaurs as crude 'paleogravity indicators,' expansion and the reduction in gravity began in the Middle-to-Late Triassic with gravity reaching a minimum of 0.8 g sometime during the Jurassic. (The dating of the onset of expansion corresponds with the views of both Carey and King, though both believe that expansion continued into the Cenozoic.) According to classical physics, gr^-2 ; at constant mass, a reduction in gravity to 0.8 g requires a radius 11.8% larger than at present. The current radius of the Earth is 6371 km; its surface area (4?r^2 ) is 5.1 x 10^8 km^2 . At 0.8g, the radius would be 7123 km with a total surface area of 6.41 x 10^8 km^2 ; therefore, the net increase was 751 km in radius and 1.31 x 10^8 km^2 in surface area. /Staurikosaurus/, the oldest dinosaur, appeared in the Carnian age of the Late Triassic (225-230 Ma); /Barapasaurus/, the first truly gigantic dinosaur, appeared in the Early Jurassic, some 40-45 m.y. later. If total expansion occurred during this interval, then surface area increased at an average rate of 2.9-3.3 km^2 yr^-1 . Extending the expansion interval to the end of the Jurassic (144 Ma), when the largest dinosaurs existed, yields an average rate increase of 1.5-1.6 km^2 yr^-1 over a period of 80-85 m.y. Thus, creation of seafloor at the rate of 3 km^2 yr^-1 through seafloor spreading, together with the subduction of 1.5 km^2 yr^-1 between 230-144 Ma, would produce the required additional surface area and increased radius. Although these rates of spreading and subduction are extreme when compared to modern rates,^5 i.e. a high rate of spreading and a low subduction rate, they certainly are not unreasonable. ------------------------------------------------------------------------ ^1 Steiner, 1977. ^2 Carey, 1976; Carey, 1988. ^3 King, 1983. ^4 Owen, 1983. ^5 Chase, et al., 1975; Steiner, 1977. Home | Previous | Next © Copyright 1990, 2005, William Carnell Erickson, Inc. All rights reserved.