Editing Death Valley National Park (section)

===Rifting and deposition===
[[File:Late Precambrian Noonday Formation.jpg|thumb|left|The Noonday Dolomite was formed as a carbonate shelf after the break-up of [[Rodinia]].]]
A [[rift]] opened and subsequently flooded the region as part of the breakup of the supercontinent [[Rodinia]] in the [[Neoproterozoic]] (by about 755&nbsp;million years ago) and the creation of the [[Pacific Ocean]]. A shoreline similar to the present [[Atlantic Ocean]] margin of the United States lay to the east. An [[algal mat]]-covered carbonate bank was deposited, forming the Noonday Dolomite.<ref name="Wright1997p632">{{harvnb|Wright and Miller|1997|p=632}}</ref> Subsidence of the region occurred as the [[continental crust]] thinned and the newly formed Pacific widened, forming the Ibex Formation. An angular [[unconformity]] (an uneven gap in the geologic record) followed.

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 shelf|continental shelves]].<ref name="Wright1997p634">{{harvnb|Wright and Miller|1997|p=634}}</ref> Three formations developed from sediment that accumulated on the wedge. The region's first known [[fossil]]s of complex life are found in the resulting formations.<ref name="Wright1997p634"/> Notable among these are the [[Ediacaran|Ediacara fauna]] and [[trilobite]]s, the evolution of the latter being 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 [[Bahama]]s), which lasted for the next 300 million years of [[Paleozoic]] time (refer to the middle of the [[:image:Geologic events in Death Valley.png|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-northeastern coastline trend generally ran from [[Arizona]] up through [[Utah]]. The resulting eight formations and one group are {{convert|20000|ft|km|0}} thick and underlay much of the Cottonwood, Funeral, Grapevine, and Panamint ranges.<ref name="Wright1997p634"/>