Abstract: The 27th Cave is one of the localities of the Dayao site that was excavated in 1986. It contains four depositional layers, with a total thickness of nearly 2 meters, three of which yielded chipped stone. All of the 520 stone artifacts were manufactured from local chert coming from the outcrops around the site. In terms of the retouched tool inventory, all assemblages from the 27th Cave are clearly flake-based, and there is little variation among the various layers except for two prepared microblade cores in layer 1. Hard-hammer percussion seems to have been the dominant technique for detaching flakes, and the blanks are irregular in shape and size. Retouched tools are typologically and technologically characteristic of the northern Chinese Late Paleolithic. The most abundant retouched tools are side scrapers, most of which are manufactured on relatively flat flakes. Denticulates are the second most common artifact class. Other tool forms, including choppers, spheroids, points, notches, and endscrapers, occur in small numbers. Based on the typology and nature of the sediment, the 27th Cave is suggested to be dated to not earlier than Late Paleolithic.

Key words: Chipping stone; Flake technology; Microblade; Dayao; Inner Mongolia