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We used the cosmogenic nuclides, Be-10 and Al-26, as cosmic-ray dosimeters to track sediment movement across the incised Chemehuevi Mountain piedmont surface. The Piedmont extends 12 km from highland source basins to an ephemeral wash at the toe of the piedmont. Nuclide activity in sediment from steep source basins and from the bedrock pediment allows us to estimate rates of sediment generation and thus the rate at which sediment is supplied to die piedmont from weathering rock. Analysis of amalgamated sediment samples, collected along 4-km-long transects spaced at 1 kin intervals from the mountain front provide context for understanding nuclide activity in sediment samples collected from two soil pits and demonstrate that sediment steadily moves down the channel network. Samples from the two soil pits allow for estimates of sediment deposition rates and thus further illuminate piedmont history.

Model results suggest that the Chemehuevi Mountains are eroding about 40 mm ky(-1) whereas the mountain-proximal bedrock pediment and the interpiedmont Saw-tooth Range are eroding more slowly, 10 to 21 mmn ky(-1) and 9.5 mm ky(-1) respectively. Cosmogenic nuclide profiles in two soil pits suggest a complex history of deposition (at rates between 19 to 34 mm ky(-1)) and stability over the past 60 ky. A change in process from sediment deposition to sediment transport occurred distally on the piedmont approximately 8 ky ago, while the mid-piedmont piedmont surface has been stable since the mid-Holocene.

The incised Chemehuevi Mountain piedmont is changing at rates similar to planar and uniformly active piedmonts such as those adjacent to the Iron and Granite Mountains. All three piedmonts have average sediment grain velocities of decimeters per year, long-term source basin erosion rates between 35 to 40 mm ky, depositional hiatuses around the Pleistocene-Holocene climatic transition from moister to drier conditions, and Pleistocene deposition rates of 18 to 39 mm ky. Such similarity in piedmont behavior, despite clear differences in morphology and appearance, might suggest large scale geologic and climatic controls on the generation, transport and deposition of sediment in the Mojave Desert.