<p>ANS:The
Morrison Formation was deposited associated with the Sundance Sea. These deposits are
mostly derived from weathering and erosion of mountains formed during the Nevadan orogeny.
These sediments include sandstones, mudstones, shales, and occasional conglomerates and they
contain many dinosaur fossils as well. In contrast, the sediments deposited in the Cretaceous
Interior Seaway were distinguished by a succession of transgressions and regressions and
included detrital sediments as well as carbonates. At the end of this period, coal deposits were
formed in part of this area.</p>