is determined by the distance of the high ridge of the Coast Range from the ocean, narrow at the west, increasing toward the central part, where the San Gabriel and Santa Ana valleys extend northerly and easterly sixty miles or more from Los Angeles to the mesas and foothills of the high range on the east, and then narrowing again to its southern limit just below San Diego Bay. Owing to its environment and exposure, as well as its latitude, this region has more heat than the more northerly coast sections, though in its extensions away from the ocean it has had, in some places and at long intervals, a brief drop in temperature to a degree as low as other valleys with similar elevations. It is on the whole, however, most equable in its temperature and by this widely known characteristic has attracted settlement and development in some respects beyond other districts of the State. The products are large and various, including most of the present output of citrus fruits and walnuts, most of the beans, much of the sugar-beets and truck crops for overland shipment, and dairy, poultry, hay, grain, and orchard fruits for a part of its local consumption. It is for the most part an irrigated district, though some crops are successfully grown along the coast by rainfall and on the uplands away from the coast good results are attained by dry-farming. The rainfall average varies locally from 10 to 18 inches, part of which comes from the Mexican storm system in summer and early fall showers which are of little account except in truck fields and flower-gardens, and occasionally in

terfere seriously with harvesting of beans and other field crops.

The Interior Valley region.

This region extends from the north end of the Sacramento Valley southward through the length of the San Joaquin Valley to the Tehachapi Mountains, which form its southern boundary. This pair of connected valleys constitute what is properly called “The Great Valley of California," about 400 miles long and from 40 to 60 miles wide. It contains a larger body of productive land than any other subdivision of the State. Central on the west side of the Great Valley are the deltas of the two great rivers whose names designate their respective valleys. The break in the Coast Range which gives outlet for their waters to the Bay of San Francisco, also admits an interior extension of coast influences that modify climatic conditions over these deltas and adjacent lands, as is indicated by the circular intrusion of Division 2 into Division 4 as shown on Plate III. This circular area is somewhat different in climatic characters, however, from those of either of the divisions to which it is related, for it is a blending of the two.

In the extreme southeast part of the State another area marked Division 4 is connected with the Great Valley because it has closer resemblance thereto, both in characters and products, than to any other region. It comprises the Imperial Valley and other valleys adjacent to the Colorado River. It differs from the Great Valley in having a higher tempera

ture both in summer and winter and in its smaller rainfall, which is practically negligible, as all cropping is conditioned on irrigation.

The Great Valley differs from the coast regions west of it in having a lower winter temperature, because its dominating environment is the snow-clad Sierra on its east side and the Coast Range on the west. This contrast is more marked through the central and southward stretches of the Great Valley. Another contrast is in summer temperatures which may average more than twenty degrees higher on the east than on the west side of the Coast Range, as the ocean then has a cooling effect on the regions open to its influence.

In rainfall the Great Valley has such marked differences that generalization is impossible. Roughly speaking, the Sacramento Valley may be said to have from 20 to 40 inches on different years, while the San Joaquin has from 4 to 16. This variation in rainfall is, however, overcome by irrigation which is practiced in the Great Valley over a greater acreage than in any other section of the State. The products include all grown anywhere in California. The Great Valley has always produced the chief part of the grain and hay products of the State. Its more recent development has included all of the raisin output and the chief part of the alfalfa, on the basis of which it now leads in dairy industries. It stands first in the production of shipping and canning fruits and in all fruits grown for drying except prunes and on the edges of the valley the citrus fruit product