arroyo A gully found along valley floors in an arid or semi-arid region and possessing steep or vertical walls cut in fine-grained cohesive sediments. The floor is flat and usually sandy. Arroyos are found especially in the south-western United States, parts of India, South Africa, and around the Mediterranean.

arroyo Gully found along valley floors in an arid or semi-arid region and possessing steep or vertical walls cut in fine-grained cohesive sediments. The floor is flat and usually sandy. Found especially in the south-western United States, parts of India, S. Africa, and around the Mediterranean.

ar·roy·o / əˈroiˌō/ • n. (pl. -os) a steep-sided gully cut by running water in an arid or semiarid region.