bolson

Etymology
From.

Noun

 * 1)  A relatively flat and arid valley that is surrounded by mountains and that drains into a central basin.
 * 2) * 1974, U.S. Department of the Interior, Geological Survey Research Professional Paper 900, p. 120 (Google preview):
 * In three separate bolsons in West Texas, electrical-resistivity soundings and seismic-refraction profiles have been used . . . to estimate the alluvium thickness and ground-water quality.