Sag pond

A sag pond is a body of water collected in the lowest parts of a depression formed between two sides of an active strike-slip fault zone. Sag ponds may be useful identification features in aerial photographs for mapping faults.

Sag ponds of various sizes can be found along the San Andreas Fault, most notably within the Carrizo Plain and Sierra Pelona Mountains. Some have been converted into reservoirs like the San Andreas Reservoir near San Bruno, California.

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