Wilderness Gateway archaeology, Idaho (1977)

Rocky Mountain Geology, 2014

Geomorphic mapping coupled with optically stimulated luminescence (OSL) dating reveal the late Pleistocene history and geomorphic development of the narrow canyon of Big Creek, a major tributary to the Middle Fork of the Salmon River in central Idaho. The most prominent feature in the region is the Soldier Bar landslide, which consists of slumped and rotated blocks of Mesoproterozoic quartzite bedrock that slid northward from an arcuate headwall, damming both the east-flowing Big Creek and Goat Creek, a southdraining tributary. Water impounded behind the dam ultimately overtopped the deposit. Overflow laterally eroded a flight of four downstream-sloping spillway terraces into the jumbled landslide deposit at elevations over a range of 450 ft (137 m). These elevations, initially estimated from 1:24,000 topographic maps with 40-foot contours, are 4,500 ft (1,372 m), 4,340 ft (1,323 m), 4,200 ft (1,280 m), and 4,050 ft (1,234 m).

Scientific Investigations Map, 2005

1998

Geoarchaeology, 2004

Archaeological excavations at the Cooper's Ferry site (10IH73), located in the lower Salmon River canyon of western Idaho, revealed a stratified sequence of cultural occupations that included a pit feature containing stemmed points. However, radiocarbon ages determined on charcoal and bone in the pit feature range between ca. 12,000 yr B.P. and 7300 yr B.P. By considering the effects of postdepositional processes on dated samples, and by comparing the lithostratigraphy, pedostratigraphy, and stable isotope geochemistry of pedogenic carbonates from Cooper's Ferry with other well-dated stratigraphic sections in the canyon, site geochronology is clarified. Based on the presence of key radiocarbon ages and distinctive stratigraphic criteria, we argue that the initial occupation and interment of lithic artifacts in a pit feature at Cooper's Ferry occurred during the late Pleistocene, between ca. 11,410 and 11,370 yr B.P., and not during the early Holocene. Records of geomorphic change and paleoenvironmental proxy data from the site reveal that early occupation in the lower Salmon River canyon corresponds with evolving riparian ecosystems, which must be considered as a contextual aspect of local prehistoric cultural ecology.

1998