The Clark Creek Cache in West-Central Montana

Abstract

The majority of Precontact lithic caches from Montana cannot be chronologically placed, because they lack primary context with radiometrically datable organics or are not composed of obsidian, a datable natural glass. Dated obsidian from caches can also be positively traced to its geologic source. A rare such cache of largely obsidian pieces was found on the Sieben Ranch in 2011. Forty-three obsidian flakes and four chert flakes were observed partially exposed inside a 21-cm-diameter pit. X-ray dispersive fluorescence analysis attributed obsidian to the Bear Gulch source in the Centennial Mountains area of southwestern Montana and southeastern Idaho, approximately 280 km distant. Hydration dating suggests that the caching event occurred c. 444 ± 18 hydration years before present (HYBP). The unidirectional core technology applied to produce the majority of the pieces and the resulting large, curved, blade-like, retouched flakes is unexpected for the Late Precontact Period in the Northern Plains and Intermountain Regions.