Title: Death Valley National Park: Description (DesertUSA)
Headings: Death Valley National Park
Death Valley National Park
Description
Park History
Natural History
Plant Life
Animal Life
Geology
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Content: Wild burros, descendants of animals lost or abandoned by prospectors and miners, became so numerous they overgrazed the natural vegetation and endangered native animals who are dependent upon it. The burros have, for the most part, been rounded up and removed from the park. Geology
The geologic history of Death Valley is complex and involves different types of fault activity at various times, as well as crustal sinking, volcanic activity and erosion. Death Valley is a graben -- a rift valley -- formed by the sinking of the bedrock lying between parallel, uplifted, tilt-block mountain ranges to the east and west, the Amargosa and the Panamints. A type of fault activity called block faulting, in which huge pieces of rock move vertically, began to form Death Valley about 30 million years ago. The sinking of crustal blocks and the uplift of the adjacent mountain ranges to form the great depression has been occurring for millions of years and continues to the present time. As the mountains rose, erosion began to wear them down creating the numerous sedimentary deposits and alluvial fans. Intermittent streams, resulting mostly from bursts of infrequent rain, rushed down the steep canyons scouring boulders, soil and debris, then depositing it on the valley floor at the canyon's mouth. As the valley sank, it was filled with sediments eroded from the surrounding mountains. In the central part of the Death Valley, the bedrock floor is buried beneath as much as 9,000 feet of sediment.