The arid, sparsely vegetated terrain of this region contrasts sharply with deep blue International Amistad Reservoir that is located on the United States-Mexico border. The Rio Grande feeds into Amistad from the northwest and continues its southeasterly course. Devils River and its deeply incised canyon, cut through limestone and sandstone rocks, enters the reservoir from the northeast. Three light, intermittently flowing river courses and their canyons are discernible—two are on the Mexican side of the border at the western end of the reservoir, and the third flows into the Rio Grande southeast of Del Rio, east of which appear the runway and apron of Laughlin Air Force Base (middle left edge).