Alluvial fans near Badwater, Death Valley National Park, Inyo County, California

Aerial view of alluvial fans located at the mouths of canyons along the western flank of the Black Mountains in Death Valley National Park. Badwater, the lowest elevation in North America (-282 feet;-86 m). The alluvial fans form from sediments carried by episodic debris floods and debris flows draining from canyons in the Funeral Range. The sediment overload in the flood is dropped on the alluvial fan where the speed of the flood slows at the change in slope. Sediments fill broad channels on the alluvial causing the drainage to constantly shift across the surface, gradually building up the relatively even cone- or fan-shaped alluvial deposit. Coarser materials (boulders) generally accumulate at the top of the fan, whereas finer materials (sand, silt, and clay) are transported down slope to the basin.

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