Great Basin National Park - Geologic History

Geologic History

Many of the rocks formed during the Cambrian,when the region lay at the edge of a continental landmass called Laurentia. These rocks include the Cambrian strata. As the Paleozoic Era progressed, several intensified geologic events occurred, including repeated episodes of faulting, and in turn, orogenies which involved upward lifting of a metamorphic core complex, creating mafic and rhyolitic dikes and stills. Extensive volcanism also occurred during the middle to late Cambrian, contributing further to the uplift of the area. This also contributed to a second round of block faulting, in which conglomerates, ash flows, and tuffs accumulated in the Snake Range.

Both continuous and intermittent fault movements also occurred, with individual fault surfaces on both sides of the Snake Range thinning and stretching.

Glaciation

Glaciation, mostly during a series of ice ages in the Pleistocene, heavily eroded the peaks of the Snake Range, leaving canyon walls, U-shaped valleys, cirques, and moraines throughout the range.

Lehman Caves

The Lehman Cave system began forming approximately 550 million years ago (during the Cambrian) while it was still submerged in a relatively warm, shallow ocean. The caves are made up of a marble and limestone solution, for the most part, that forms the many cave decorations throughout the caverns.

The cave system became much deeper during the Pleistocene, when a prolonged and increased flow of water eroded through the cave's fracturing bedrock. Eventually, the water level dropped, leaving glare rooms and cavities in the rock, creating the depths of the Lehman Caves system.