of Death Valley spread the Mojave and Colorado Deserts. The Mojave is an expanse of ancient dried lake bottoms, short rugged ranges, and immense sandy valleys. Parts of the Colorado Desert lie below sea level—250 feet below at its lowest point. In its southern end is the fertile Imperial Valley, largely reclaimed from the desert for agricultural use by irrigation, where the Salton Sea, formed when the Colorado River broke its banks in 1905, floods an ancient lake bottom.
In addition to the Great Valley in the north and the coastal district (including the rich Los Angeles Basin and Santa Clara and San Fernando Valleys) in the south, cultivated lowlands occur elsewhere in the State. Below San Francisco Bay stretches another Santa Clara Valley; and southeast of Monterey Bay, between the Santa Lucia and Gabilan Ranges, lies the long Salinas Valley. North of San Francisco in Sonoma, Mendocino, and Humboldt Counties are similar areas. The northeast corner of the State, hemmed in by steep ranges, is suitable for cattle raising and restricted agriculture despite its lava beds and sagebrush.
In the whole 4OO-mile length of the Great Valley there is only one break in the mountain walls through which the waters of the interior can escape to the sea. Behind the Golden Gate at San Francisco, cutting across the full width of the Coast Range, is a great gap through which passes almost the entire drainage of the Great Valley. Into Suisun Bay pour the waters of the Sacramento and San Joaquin Rivers; they empty through Carquinez Strait into San Pablo and San Francisco Bays, and through the Golden Gate into the Pacific Ocean.
The scantily forested eastern flanks of the Coast Range contribute no stream lasting enough to reach either the Sacramento or the San Joaquin in the dry season; but down the western slopes of the Sierra, tributaries pour through precipitous canyons to the great rivers at each end of the valley. Fed by Mount Shasta's melting snows, the Sacramento, California's largest river, is joined by the Pit, McCloud, Feather, Indian, Yuba, and American Rivers as it flows southward 350 miles to its confluence with the San Joaquin in the Delta region. The Sacramento's lower course is through a marshy plain partly inundated yearly. The San Joaquin, whose valley comprises more than three-fifths of the central basin, flows northward from its headwaters in the mountains of Fresno County. Into it drain the waters of the Fresno, Merced, Tuolumne, Stanislaus, Calaveras, Mokelumne, and Consumnes Rivers, together with many smaller streams.
The seaward slopes of the Coast Range are drained by the Klamath (joined by the Scott and Trinity), Mad, Eel, and Russian Rivers north of San Francisco, and south of it by the Salinas, Santa Maria, Santa Ynez, Santa Clara and other secondary rivers, many of them intermittently dry. Southern California's so-called rivers—the Ventura, Los
