5. North America 5.1 Lower Jurassic
Smith, P. L.; Beyers, J. M.; Carter, E. S.; Jakobs, G. K.; Pálfy, J.; Pessagno, E.; Tipper, H. W.
published: Sep 15, 1994
ArtNo. ESP026003101006, Price: 29.00 €
Lower Jurassic rocks are known along the Pacific margin of North America from Mexico to Alaska (Westermann 1992). This report deals with fossils from the allochthonous terranes and the western margin of the craton; excluded are faunas from the geographically adjacent areas of northern Alaska (e.g. Imlay 1981), northern Yukon (e.g. Poulton 1991) and eastern Mexico (e.g. Erben 1956). Fossiliferous Lower Jurassic rocks of California are separated from the platformal rocks of western Nevada by the Sierra Nevada batholith where roof pendants yield rare and poorly preserved fossils Oones & Moore 1973). In Oregon, limited breaches in the extensive Tertiary volcanic cover have revealed marine Lower Jurassic rocks in the east-central and northeastern parts of the State. The allochthonous terranes of western Canada and southern Alaska were the sites of deposition of great thicknesses of marine Lower Jurassic rocks derived from volcanic activity and the weathering of volcanic rocks. By contrast, correlative marine sequences on the western margin of the craton in what is now western Alberta and northeastern British Columbia, are thin and composed entirely of cratonal sediments. Terrestrial rocks are restricted to the Colorado Plateau in the United States where the Glen Canyon Group has yielded an important vertebrate fauna.