bolson

noun

1. (Southwestern, US)A relatively flat and arid valley that is surrounded by mountains and that drains into a central basin.

   “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.”

   “The image of a colossal purse is helpful in envisioning a bolson in the landscape: an extensive, saucer-shaped basin, closed at the bottom and surrounded on all sides by mountain slopes.”

   “The water in the Mesilla Bolson, which is recharged by the river above it, is part of a major lawsuit between Texas and New Mexico. . . . A settlement could impose new restrictions on wells tapping the bolson in both states.”