Deep-basined metates are frequently found in early sites on the southern California coast, but the faces of the accompanying manos usually are only moderately convex. Mano faces examined by the writer never have been sufficiently excurvate to make contact with the grinding surfaces of the deeply ground metates. This presents an interesting problem: how were the manos manipulated on the metates?

An examination of specimens from Oak Grove sites 7, 21, and 79 (Rogers, 1929) and the Smithsonian Institution River Basin Surveys’ sites 4SBa477 and 4SBa485 in Santa Barbara County, California, reveals the following associations and characteristics. Slab, shallow-basined, and deep-basined metates are found in association. The first two types exhibit an unbroken grinding area, but specimens of the latter almost invariably have a slight shoulder running at least a part of the way around the basin, the transition between a slightly concave ground area and the deeply ground cavity.