Bajada (geography)

A bajada consists of a series of coalescing alluvial fans 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.^[1] The usage of the term in landscape description or geomorphology derives from the Spanish word bajada, generally having the sense of "descent" or "inclination".^[2]

Formation and occurrence

Bajada in Iran's Fars province

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.^[3] The sediment is transported across a pediment into a closed basin where the bajadas grade back into a pediment, making the boundary difficult to distinguish. Bajadas frequently contain playa lakes.^[4] 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.^[3]

References

^ "Bajada | Deserts, Alluvial Fans, Floodplains | Britannica". www.britannica.com. Archived from the original on Dec 2, 2023. Retrieved 2024-04-16.
^ Handy Spanish-English and English-Spanish dictionary. University of Michigan. New York, Philadelphia Hinds, Hayden & Eldredge, inc. 1912.{{cite book}}: CS1 maint: others (link)
^ ^a ^b "alluvial fan - National Geographic Education". 2015-06-26. Archived from the original on 2015-06-26. Retrieved 2024-04-16.
^ Easterbrook, Don. Surface Processes and Landforms. Upper Saddle River: Prentice Hall, 1999. Print. P. 162. Accessed 9 October 2012.