Pediments

Erosional surfaces at mountain bases.

Pediments/ Cima Dome.

 Formation and Morphology

         Pediments are gently sloping plains of erosion that are formed by running water in semiarid to arid environments. They form at the base of a receding mountain front over periods of intense rainfall that cause fluvial gravel to wash over the receding mountain front, resulting in cliff retreat. Pediments are composed of bedrock overlain by a thin layer of evenly distributed alluvium originating from the retreating mountain front..

Ecology

During our time at Cime Dome, we saw a variety of fauna that covered the dome. The main plant present was the Joshua Tree. Cima Dome is famous for its vast amount of Joshua Trees and has one the densest populations. It is also a critical habitat for desert tortoises, which have been listed as a threatened species since 1990. On the dome, we saw evidence of fire scars from the dome fire of 2020. This fire started from a lightning strike that spread hot and fast due to strong winds. The fire burned for over 36 hours because of the lack of firefighting resources in the area. Over 25% of Joshua trees were burned and it was the largest wildfire in California’s wildfire season. Recovery from this fire will be difficult for these trees because regrowth and propagation are not adapted to surviving this intense of a wildfire. Also, there are concerns of introduction of invasive species after the fire, like red brome, which is flammable and can lead to more wildfires. While we were at Cima Dome, we could still see hundreds of burned trees, but some of the area's vegetation was recovering.  

Active processes

Since  pediments are erosional surfaces and are developed from sheets of water, intense rainfalls can cause fluvial gravel to wash over and cause cliff retreat erosion.

There is also a lot of freeze-thaw erosion.