In 2010, Paleocultural Research Group and the Grand Mesa, Uncompahgre, and Gunnison National Forests jointly carried out an archaeological assessment of the Uncompahgre Cirque site (5HN1098), an extensive quarry workshop located high on the east flank of Uncompahgre Peak. Funding for the project was provided by the Forest Service and History Colorado's State Historical Fund. The site, located at an elevation of 3,840 m, consists of a dense scatter of flaking debris and chipped stone tools covering 1.15 ha (2.8 ac). Artifacts are scattered throughout this area but are visible primarily in four concentrations. The 2010 effort focused on the largest and densest of the four, designated Locus 1. Archaeological fieldwork in Locus 1 included smallscale hand excavation, intensive surface mapping, and targeted surface collection. The research team also surveyed a small portion of the valley adjacent to Uncompahgre Cirque. Subsequent laboratory analyses of recovered artifacts included minimum analytical nodule analysis of surface-collected debris aggregates; individual flake analysis and mass analysis of excavated flaking debris; technological analysis of stone tools; and compositional and hydration analysis of obsidian artifacts. Multiple lines of evidence together indicate that the site was occupied briefly between about 5900 and 5700 calendar years ago. All four radiocarbon dates from the site are statistically equivalent, yielding a weighted mean age of 5038±19 14 C yr B.P. This mean age spans at two standard deviations the period from 3944 cal B.C. to 3776 cal B.C., or a total of 168 calendar years. Obsidian artifact hydration rim thickness distributions point to a brief occupation or short series of brief occupations within this period. Stratigraphic data bolster the inference that the occupation at Uncompahgre Cirque was brief. Artifacts primarily occur in a single zone near the base of a prominent paleosol. The presence of well-defined chipped stone features primarily representing the reduction of individual raw material nodules testifies to the remarkable integrity of the site's cultural deposits. The principal activity at Uncompahgre Cirque was reduction of chert nodules quarried on the high, narrow ridge immediately north of the site. Blanks prepared for off-site transport and use include large flakes, multi-directional cores, and both early-and late-stage bifaces. Flint knappers at Uncompahgre Cirque also manufactured a variety of tools for on-site use in hide processing, woodworking, animal butchery, or other tasks. These include expedient flake tools as well as patterned end scrapers and bifaces. Some of the tools produced from local stone for on-site use were made from heat-treated flakes or nodules. A notable feature of the workshop is the presence of cores, tools, and flaking debris made from imported raw materials, including obsidian from northern New Mexico and quartzite, chert, and possibly other materials likely from the Gunnison basin and central Colorado. The diversity of imported raw materials sugge...