Bajadas coming down from the Providence Mountains

A bajada consists of a series of coalescing

alluvial fans An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

along a mountain front. These fan-shaped deposits form by the deposition of sediment within a stream onto flat land at the base of a mountain.Desert Processes Working Grou
"Summary: Alluvial Features, Bajadas"
, ''Knowledge Sciences, Inc.''. Retrieved on 9 October 2012 The usage of the term in landscape description or

geomorphology Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...

derives from the

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...

word ''bajada'', generally having the sense of "descent" or "inclination".

Formation and occurrence

When a stream flows downhill, it picks up sediment along with other materials. As this stream emerges from a mountain front, the sediment carried begins to be deposited, such that coarser sediment is deposited closest to the base and the finer sediment grades outwards and deposits in a fan-shape away from the mountain face.National Geographic Society
"Alluvial Fan"
''National Geographic''. Retrieved on 9 October 2012 The sediment is transported across a

pediment Pediments are gables, usually of a triangular shape. Pediments are placed above the horizontal structure of the lintel, or entablature, if supported by columns. Pediments can contain an overdoor and are usually topped by hood moulds. A pedimen ...

into a closed basin where the bajadas grade back into a pediment, making the boundary difficult to distinguish. Bajadas frequently contain

playa lakes A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline c ...

.Easterbrook, Don. Surface Processes and Landforms. Upper Saddle River: Prentice Hall, 1999. Print. P. 162. Accessed 9 October 2012. Bajadas are common in dry climates (e.g., the Southwestern US) where flash floods deposit sediment over time, although they are also common in wetter climates where streams are nearly continuously depositing sediment.

References

{{reflist Sedimentology Fluvial landforms