and at the south end it is closed by the Tehachapi Range. The counties north of the valley are rugged and mountainous, and are largely covered with forest. Southern California, which comprises about one-third of the state, consists of a series of mountain ranges running mostly parallel with the coast, east of which there is a desert area which lies partly below sea level. Nearly seven-eighths of the surface of the state are covered by mountains.
The surface, soils, and agriculture of California are extremely diversified; and, owing to the nearness of the ocean and the prevailing westerly winds, there is a very wide range in temperature and rainfall. In the northern portion the soils are derived from lavas and volcanic ash; in the southern part they are sandy loams, and on the overflow lands of the rivers clay loams. The year is divided according to the rainfall into a dry and a wet season. The greatest rainfall comes in the winter months, and the months of June, July, and August are almost rainless over the greater part of the state. The amount of rain varies greatly in different years and in different sections of the state. At San Francisco the annual rainfall ranges from 7 to 49 inches. In the northwest corner of the state it is 60 or more inches, while in the Imperial Valley, one of the dryest regions in the United States, it is from 1.5 to 2.5 inches. In the Death and Saline valleys there is practically no rain. The winters are much milder than on the Atlantic Coast, and there are many localities where there are 200 clear days in a year.
Of the 99,617,280 acres of land surface, 20,000,000 acres are waste land, bare mountain ledges and deserts; 60,000,000 acres are in forest and mineral lands; and only a part of the remaining 20,000,000 acres is arable and suitable for agriculture. The land requiring irrigation is confined to the interior valleys and the southern coast. From San Francisco northward along the coast the heavy rains and summer fogs furnish sufficient moisture for the needs of agriculture. Existing enterprises are capable of irrigating about 4,219,000 acres, while 7,800,000 acres are included in projects. Nine-tenths of this land are watered from streams, and one-tenth is served by pumping-plants. Alfalfa and orchard and tropical fruits are the crops most extensively irrigated.
THE GREAT CENTRAL VALLEY
The Great Central Valley is 450 miles in length and 40 miles in width, so that the level area contains 18,000 square miles. The only drainage outlet of the valley is the Golden Gate, near San Francisco, which in its narrowest part is only a mile wide. The northern portion is drained by the Sacramento, and the southern by the San Joaquin River, the two rivers uniting before entering into San Francisco Bay. In the delta region of the two rivers, especially in Suisun Bay, there are 50,000 acres largely covered with tule (Scirpus lacustris, var. occidentalis), a nectarless, wind-pollinated, grasslike plant belonging to the sedge family. The valley of the Sacramento River is only about half the width of that of the San Joaquin; but, owing to the greater rainfall, it has a much greater water supply. Under the present system of irrigation the area of irrigable land in the Sacramento Valley is 630,000 acres; in the San Joaquin Valley, 2,150,000 acres. The San Francisco Bay region, where there are 5000 acres of irrigable land, is not included in the above figures.
The chief source of surplus honey in the Central Valley is alfalfa. A large quantity of amber-colored honey is stored from the second and third crops; but the first crop is of very little value, being cut before the blossoms appear. The first pollen and nectar gathered in some sections are from the Eucalyptus groves. There are nearly 2000 acres of these trees in the Berkeley Hills behind Richmond, and there is another large center between Newark and Arden. Willows may yield a surplus in Sacramento, Fresno, and Tulare counties; and in mid-summer and