kimerajamm
Joined: 28 Nov 2010
Posts: 785
|
 Posted: Sat May 07, 2011 4:16 pm Post subject: The sandy mudflats |
 |
|
A true ocean basin developed to the west, breaking all the earlier formations along a steep front. A wedge of clastic sediment then began to accumulate at the base of the two underwater precipices, starting the formation of opposing continental shelfs.[29] Three formations developed from sediment that accumulated on the wedge. The region's first known fossils of complex life are found in the resulting formations.[29] Notable among these are the Ediacara fauna and trilobites, both part of the Cambrian Explosion of life.
The sandy mudflats gave way about 550 million years ago to a carbonate platform (similar to the one around the present-day Bahamas), which lasted for the next 300 million years of Paleozoic time (refer to the middle of the timescale image). Death Valley's position was then within ten or twenty degrees of the Paleozoic equator. Thick beds of carbonate-rich sediments were periodically interrupted by periods of emergence. Although details of geography varied during this immense interval of time, a north-northeasterly trending coastline generally ran from Arizona up through Utah. The resulting eight formations and one group are 20,000 feet (6 km) thick and underlay much of the Cottonwood, Funeral, Grapevine, and Panamint ranges.[29]
Dallas SEO
paralegal degree colorado |
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
