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Uplift on this fault is about 0.01–0.03 mm per year. This movement, combined with the activity of the adjacent Owens Valley and Lone Pine faults, is responsible for the continuing rise of the Sierra Nevada Mountains. [1]
This implied a late-Cenozoic residency at depth, meaning the unroofing and uplift of the Sierra Nevada block happened rapidly near the end of the Cenozoic. Geologic evidence in the form of erosion surfaces, paleo-canyons, and related deposits suggests the majority of the uplift was achieved prior to 4-10Ma. [5]
The uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones (areas with similar plant and animal communities). Uplift continues due to faulting caused by tectonic forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra.
California's Sierra Nevada Mountains (formed by delamination) as seen from the International Space Station.When a large portion of dense materials was removed under the tectonic plate at this location, the remaining portion of the crust and lithosphere underwent a rapid uplift forming this mountain range.
Through a combination of uplift of the Sierran block and down-dropping of the area to the east, the Sierra rose upward. Rising far more steeply to the east than the west, the entire Sierra Nevada can be thought of as an enormous tilted fault block with a long, gentle slope westward to California's Central Valley and steep eastern slope. [2]
10 million years ago, vertical movement along the Sierra fault started to uplift the Sierra Nevada. [2] Subsequent tilting of the Sierra block and the resulting accelerated uplift of the Sierra Nevada increased the gradient of western-flowing streams. The streams consequently ran faster and thus cut their valleys more quickly.
An example is the Sierra Nevada range, where delamination created a block 650 km long and 80 km wide that consists of many individual portions tipped gently west, with east facing slips rising abruptly to produce the highest mountain front in the continental United States. [18] [19]
With crustal extension, a series of normal faults which occur in groups, form in close proximity and dipping in opposite directions. [4] As the crust extends it fractures in series of fault planes, some blocks sink down due to gravity, creating long linear valleys or basins also known as grabens, while the blocks remaining up or uplifted produce mountains or ranges, also known as horsts.