Few studies have been performed on coleopteran (beetle) biodiversity in mountain ecosystems and relating them to multiple environmental factors. None of the studies have examined geologic influences on beetle communities. Little coleopteran research has been performed in the Colorado Rocky Mountains. The main objectives of this study were to catalog the coleopteran fauna of a subalpine meadow in the San Juan Mountains of Colorado and investigate the role geology had in the community structure of the Carabidae (ground beetles). The study site, a 160,000 m2 plot, was located near Sultan Creek and Molas Lake in San Juan County, Colorado. Five sites were in each bedrock formation: Molas, Elbert, and Ouray-Leadville. Insects were collected via pitfall trapping in 2006 and 2007, and identified by comparison with museum specimens, museum and insect identification websites, and by taxonomic experts. Biological and physical factors were recorded for each site: detritus cover and weight, plant cover and height, plant species richness, aspect, elevation, slope, soil temperature, pH, moisture, and compressive strength, and sediment size distribution. Quantitative analyses were performed on the Carabidae community and its relationship to bedrock formations and environmental factors measured, and on the entire coleopteran abundance and its relationship to the environmental factors. I sampled 7,316 coleopteran individuals in 27 families and nearly 100 species (61 completely identified). Coleopteran abundance was influenced by plant cover, plant height, soil moisture, aspect, slope, collection site, and week collecting took place. A total of 1,236 carabid individuals representing 30 species were collected. Elevation, detritus cover, and soil temperature were significantly distinct between formations. Species richness and abundance of several species (Agonum placidum, Bembidion mutatum, Carabus taedatus, Cymindis cribricollis, Harpalus animosus, and Harpalus laticeps) differed significantly between formations, but overall there were no distinct carabid communities associated with the three formations. Carabid species richness, abundance, and biodiversity were significantly influenced by plant factors, and frequency was significantly influenced by sediment sorting. The carabid species composition was influenced (not significantly) by compressive strength, pH, plant cover, soil moisture, slope, and aspect. In conclusion, geology had less of an effect on carabidae then other environmental factors.