The Great Basin with emphasis on glacial and postglacial times

The Great Basin is a physiographic province the boundaries o f which are somewhat indefinite. Roughly it lies between the Sierra Nevada on the west and the Wasatch Mountains on the east, but its tributary valleys extend over into Wyoming. To the north it grades into the Columbia lava plateau, and to the southeast into the high plateaus near the Colorado River. Southward it merges, through the Mohave desert o f California, into the Sonoran province. It thus comprises most o f Nevada and Utah, with a fringe in California, Oregon and Idaho, and Wyoming.