The Aboriginal Population of the San Joaquin Valley, California.

Ecologically the great central valley of California forms a single unit. Nevertheless it is convenient for the purposes of this paper to divide the entire area into two portions, north and south. The vast expanse from Red Bluff to the Tehachapi is too extensive to cover demographically in a single exposition. Moreover, the northern tribes, the Wintun and Maidu, are physiographically clearly segregated from the southern by the northern extension of San Francisco Bay and the delta of the rivers. Hence we shall consider here only those peoples south of the Sacramento and American River watersheds.