A collection of recent research on the basins that characterize the Rio Grande rift as it extends from central Colorado to west Texas and the state of Chihuahua, Mexico. Most of the papers were initially presented at a symposium during the 1991 joint meeting of the Rocky Mountain and South-Central sections of the Geographical Society of America. Topics include crustal extensions, structural and tectonic evolution of the Joyita Hills, and stratigraphic consequences of episodic extension. Annotation c. by Book News, Inc., Portland, Or.