The southern Basin and Range physiographic province extends southward from the Colorado Plateau and Great Basin to the United States-Mexico boundary, and from the lower Colorado River valley eastward to the Pecos River valley (Fig. 1). This region is divided into six parts: lower Colorado River valley, Sonoran Desert, Mexican Highland section, Transition Zone-Datil-Mogollon section, Rio Grande rift zone, and Sacramento section.
The principal physiographic characteristic of the southern Basin and Range province is a series of discontinuous mountain ranges alternating with subparallel intermontane depositional basins. Most of the mountain ranges trend west-northwest to north, but a few are northeasterly. Their higher summits range in altitude from 900 to rarely above 2500 m in western and eastern parts of this region, and from 1600 to 3265 m in its central part. Intermontane-basin floors range from close to sea level near Yuma to above 1500 m altitude in the transition zone below the Colorado Plateau. The mountain ranges have diverse structures, ages, and rock types, even between nearby ranges. Exposed rocks range from Precambrian to Quaternary and include virtually all rock types: sedimentary, volcanic, plutonic, and metamorphic. Some ranges are structurally and lithologically simple, but other mountain ranges have complex structures, commonly involving many episodes of low-angle and/or high-angle faulting, folding, and/or igneous intrusion, and similarly complex stratigraphy and lithology.
Figures & Tables
Includes 5 topical chapters covering paleoclimates, dating methods, volcanism, tephrochronology, and Pacific margin tephrochronologic correlation, and 15 chapters of regional synthesis covering: the Pacific margin; the Columbia Plateau; the Snake River Plain; the major pluvial lakes of the Great Basin; the Basin and Range in California, Arizona, and New Mexico; the Colorado Plateau; the Southern and Central Rocky Mountains; the Northern and Southern Great Plains, Osage Plains, and Interior Highlands; the Lower Mississippi Valley; the Gulf of Mexico Coastal Plain and Florida; the Appalachian Highlands and Interior Low Plateaus; and the Atlantic Coastal Plain. A large, full-color geologic map of the Quaternary deposits of the Lower Mississippi Valley, in addition to correlation charts, tables, and cross-sections relating to other chapters, is also included.