ARCHAEOLOGICAL HORIZONS IN CENTRAL CALIFORNIA By ROBERT F. HEIZER and FRANKLIN FENENGA INTRODUCTION present to the archaeological T HE the lower paper is an attempt The define of this discussion is situation in Sacramento Valley. aim to sum marize a threefold culture sequence called here Early, Middle and Late, and to place it within the general scheme of California prehistory as we understand it at the present time. Until quite recently California culture has been widely cited as endowed with an unique uniformity and unchange ableness, persisting in its simple, specific form for thousands of years. We now know this to be incorrect. Wherever intensive, planned archaeological work has been prosecuted in California, cultural differences have obtruded themselves. 1 Our type section and largest sampling is from the Mokelumne-Cosumnes river region, with additional data from the upper Sacramento valley (site 1) and the Sacramento-San Joaquin river Delta region (sites 138, 139). The Cosumnes river sites are 107,6, 120, 126, 127; the Mokelumne river sites 68, 66, 142. Site 60 on the Sacramento river is geographically intermediate as is site 99 on the lower American river. Map 1 shows the location of these sites. 2 Schenck and Dawson published, in 1929, a volume on the archaeology of the northern San Joaquin valley.3 They concluded that in this region (called Stockton-Lodi), certain sites could be differentiated by character istic cultural forms, and that these cultural divergences reflected temporal differences. But Schenck was very hesitant in offering this interpretation, and when in 1933 the Sacramento Junior College instituted an archaeolog ical program under the direction of President J. B. Lillard, it was with the main idea of gaining a general insight into the archaeology of their area, and not of a specific search for cultural sequence. Two Cosumnes river sites (126, 127) yielding the same culture were successively investigated. The third, site 107,4 soon showed itself to be stratified, the topmost level agreeing with the culture disclosed in sites 126 and 127, the bottom level something entirely different. Intermediate in this site between these two divergent cultures was a manifestation apparently of a transitional phase. In 1936 Lillard and Purves published a bulletin on the basis of this trio I See Rogers, M. 1929; Olson, 1930; Rogers, D.B. 1929. • See Schenck. and Dawson (1929; 293-305) for a good geographical description of the area. I Schenck and Dawson, 1929. , Lillard's sites 1, 2, and 3 are respectively our 127, 126, 107.