The complex was first identified by
Malcolm J. Rogers in 1919 at site SDI-W-240 in
Escondido in
San Diego County, California. He assigned the
Paleo-Indian designation of 'Scraper Makers' to the prehistoric producers of the complex, based on the common occurrence of unifacially flaked lithic
(stone) tools at their sites. In an initial synthesis, Rogers (1929) suggested that the Scraper Makers were the region's second inhabitants, following the people of the Shell Midden culture, later known as the
La Jolla complex, whose remains lie closer to the coast. However, his 1938 excavations at the C. W. Harris Site (CA-SDI-149) in
Rancho Santa Fe established that the site's San Dieguito component underlay its La Jolla component, at the base of the stratigraphic sequence. Subsequent excavations at the Harris Site confirmed Rogers' main conclusions and obtained
radiocarbon dates that placed the site's occupation as far back as 10,200 BP (8200 BCE). Characteristics suggested for San Dieguito complex assemblages, in addition to the abundant
scrapers, have included large, percussion-flaked
bifaces; flaked crescentic stones; Lake Mohave or Silver Lake style
projectile points; a scarcity or absence of milling tools (
manos and
metates); and an absence of small projectile points and pottery. ==Interpretations==