accumulations of marine sediments eroded from the Cordilleran highlands to
the west were deposited on the terrestrial redbeds of the Colorado Plateau,
forming the Jurassic Morrison Formation, well-known for fossil bones of large
dinosaurs (Fig. 158). Eastern Mexico, southern Texas, and Louisiana were also
flooded. Seas invaded South America, Africa, and Australia as well.
The continents were flatter, mountain ranges were lower, and sea levels
were higher. Thick deposits of sediment that filled the seas flooding North
America were uplifted and eroded, giving the western United States its
impressive scenery. Reef building was intense in the Tethys Sea.Thick deposits
of limestone and dolomite were laid down in the interior seas of Europe and
Asia,later to be uplifted during one of geologic history’s greatest mountain
building episodes.
After covering the birds and giant dinosaurs of the Jurassic, the next
chapter explores the life-forms and landforms of the warm Cretaceous period
and the extinction of the dinosaurs.Figure 158A dinosaur
boneyard at the Howe
Ranch quarry near
Cloverly,Wyoming.
(Photo by G. E. Lewis,
courtesy USGS)
Historical Geology