The Calico Early Man Site is an archaeological site in an ancient Pleistocene lake located near Barstow in San Bernardino County in the central Mojave Desert of Southern California. This site is on and in late middle-Pleistocene fanglomerates (now-cemented alluvial debris flow deposits) known variously as the Calico Hills, the Yermo Hills, or the Yermo formation. Holocene evidence includes petroglyphs and trail segments that are probably related to outcrops of local high-quality siliceous rock (primarily chalcedony in freshwater limestone). The Calico Early Man Site includes: Artifacts of the Lake Manix Lithic Industry (LMLI) found on and just below the surface at elevations greater than , the shoreline elevation of a freshwater Pleistocene lake which emptied approximately 18,000 years ago. Material recovered from nested Pleistocene alluvial deposits stratigraphically beneath a 100,000-year-old soil profile: a 'rock ring' (not a fire hearth) dated to 135,000 years by thermoluminescence (TL), about 200,000 years by uranium-series analysis, and about 197,000+/- 20,000 years by surface beryllium-10 (10Be) dating. The Rock Wren Biface, a large well-formed biface tool recovered from a younger nested-inset alluvial deposit at Calico: dated by sediment thermoluminescence (sediment TL) to 14,400 ±2,200 years ago. A test pit located near the discovery location is currently being excavated and is yielding artifactual material. The tools and flakes of LMLI and those found in the nested inset known as the Rock Wren Locality were probably made by modern man (Homo sapiens sapiens). Introduction The stone tools of these industries, along with preforms, lithic core, technical flakes, and pieces of angular debitage, mainly of chalcedony, are found on and in late middle Pleistocene-age fanglomerates and younger inset alluvial terraces in the Calico Hills (also known as the Yermo Hills) east of the Calico Peaks and the Calico Mountains. The location is in the central portion of southern California's Mojave Desert. Historically, this archaeological project has also been known as "The Calico Mountains Archaeological Site" and "The Calico Hills Archaeological Site". Today, it is called "The Calico Early Man Site". Manix Basin In most of the Great Basin region, Late Pleistocene and Holocene alluviation has effectively buried and sealed earlier Pleistocene sediments and possible evidence of pre-Clovis cultures. In the Manix Basin (Lower Mojave Valley) of San Bernardino County, California a fortuitous ensemble of environmental factors relating to mountain building, climatically controlled conditions for lake formation, alluviation, and erosion, faulting and folding and significant erosion of ancient lacustrine