Description
Over 4,100 feet of Paleozoic strata of Middle Ordovician through Middle Devonian age and about 3,000 feet of Oligocene, Pleistocene and Recent rocks are exposed in the Pancake Range. Approximate thickness by system and series are: Ordovician, 1,110 feet, Silurian, 626 feet, Devonian, 2,400 feet, Oligocene, 3,000 feet, Pleistocene and Recent, at least 300 feet. The Paleozoic strata have been divided into seven formations. The Tertiary rocks into one formation' and 14 members. The Paleozoic formations have been correlated where possible with lithologies described elsewhere in eastern Nevada. The sequence is typical of a miogeosynclinal facies, being composed primarily of dolomite, dolomitic limestone, limestone, and orthoquartzite. Tertiary rocks consist of a sequence of welded tuffs (ignimbrites) of Oligocene age and Pleistocene-Recent basalt flows. The ignimbrites are rhyodacitic, rhyolotic, dacitic, and andesitic in composition. Nuées ardentes covered faulted and tilted Paleozoic rocks during Oligocene time. Later in the Miocene and Pliocene Epochs the volcanic sequence was extensively faulted as part of the formation of Basin and Range structures. Periodic vulcanism in the Pleistocene and Recent has produced a series of basalt flows which lie unconformably on the older formations.
