Cougar Creek: Quantitative Assessment of Obsidian Use in the Greater Yellowstone Ecosystem

Abstract

With more than 15 sources of obsidian and other lithic materials, the Greater Yellowstone Ecosystem of Montana, Wyoming, and Idaho is one of the richest toolstone regions in northwestern North America. This article introduces a quantitative assessment technique to compare attributes of seven Yellowstone obsidians used by Native Americans over at least 11,000 years. The proposed assessment technique is replicable and adaptable to other regions. This article also analyzes the procurement, use, and distribution of the poorly studied Cougar Creek obsidian. Archaeological research documented Cougar Creek obsidian outcrops, procurement areas, and secondary processing sites. Native Americans acquired the material at surface exposures, as well as occasional trench and pit excavations. There is a significant distance decay reduction in its use, especially when compared with Obsidian Cliff obsidian. Using a weighted z-score analysis, the material attributes of Cougar Creek were compared with those of six regional obsidians to determine the factors involved in their differential use. Based on these rankings, Cougar Creek obsidian experienced low demand and usage due to poor quality and availability. In contrast, due to their high quality, abundance, and aesthetics, Obsidian Cliff and Bear Gulch obsidians were preferred for stone tool production.

The geology, geochemistry, and geographic distribution of southern Idaho obsidian

“…These would have likely been obtained through direct procurement via logistic forays, perhaps with some level of intragroup or intergroup exchange (Speth et al 2013;Newlander 2018;. A similar pattern of lithic resource use has been observed on the nearby Yellowstone Plateau (MacDonald, Horton, and Surovell 2019), where a strong preference for material from Obsidian Cliff and Bear Gulch over other available source materials is best explained by differences in material quality. Higher quality obsidian from Obsidian Cliff and Bear Gulch was heavily-utilized and transported for great distances, while lower quality Cougar Creek obsidian was used rarely and discarded within short distances of the source.…”

“…Parallel to this effort, the Northwest Research Obsidian Studies Laboratory (NWROSL), then run by Craig Skinner, built a reference collection spanning western North America, including 24 groups from 113 sampling locations in southern Idaho (Skinner, 2011a(Skinner, , 2011b(Skinner, , 2011cBlack, 2015). Ten additional source locales have been reported in and around Yellowstone National Park, east of the present study area (Park 2010;MacDonald, Horton, and Surovell 2019).…”

“…Obsidian outcrops in a multitude of locales on the margin of the plain in association with both regionally-extensive ignimbrite tuffs and smaller rhyolite flows of the ESRP-VP. The Yellowstone EC remains active and rhyolitic ignimbrites and obsidian are exposed at the surface throughout the caldera plateau (Christiansen 2001;MacDonald, Horton, and Surovell 2019).…”

“…Most source groups of the ESRP-VP have been previously identified and characterized by archaeologists, but only two (the Walcott Tuff and the Conant Creek Tuff) have been linked to their parent geologic units. The Walcott Tuff is a well-utilized source of obsidian first identified along the Snake River below the American Falls reservoir (Bailey 1992;James, Bailey, and D'Auria 1996;Holmer 1997 (Bailey 1992;Holmer 1997;Park 2010;MacDonald, Horton, and Surovell 2019).…”

“…Apart from the Walcott Tuff, the Conant Creek Tuff is the only major, regionally extensive ignimbrite that has been previously recognized as a source of obsidian from the ESRP-VP (Park 2010;MacDonald, Horton, and Surovell 2019). Obsidian of the Conant Creek Tuff is comparable in quality, workability, and appearance to that of the Walcott Tuff.…”