Paleontology and geology
The Sierra Nevada Mountains rose to their majestic heights during the Quaternary, creating a rain shadow and arid desert conditions to the east. As a result, Nevada’s climate could no longer support the vegetation and animals of earlier times. Glaciers sculpted the highest peaks of the mountain ranges across the state, and as tectonic processes stretched the continental crust, valleys continued to grow wider and fill with sediment. During cooler and wetter intervals, lakes filled many parts of these valleys and mammoths, horses, camels, and giant ground sloths roamed along their shores. Volcanic eruptions continued throughout the state, depositing ash flows and lava. This map shows Quaternary deposits in the lowland areas throughout the state.