Geology of the Tehachapi Mountains, California

The San Joaquin-Sacramento Valley, also known as the Great Valley of California, separates the Coast Ranges on the west from the Sierra Nevada on the east. The southern part of this major physiographic and structural province is about 50 miles in average width, and is terminated abruptly at its southeastern end by the Tehachapi Mountains, a range that trends roughly northeast. Uplifted principally by faulting, this mountain mass rises boldly (fig. 2) from the floor of the San Joaquin Valley-a floor so smooth and so extensive that in early days it was referred to as the San Joaquin Plains. The range also presents a rather straight and imposing, though somewhat less formidable, front toward the Mojave Desert to the southeast.