Obsidian Cliff, Park County, Wyoming, USAi

Regional Level Types
Obsidian Cliff	Cliff
Park County	County
Wyoming	State
USA	Country

Through time, several Native American cultures had knowledge of and access to different obsidian sources in the Greater Yellowstone Area. There are 19 known obsidian sources used by prehistoric peoples in the Yellowstone region spread out to the south, southwest, west, and northwest, offering choice and opportunity.

Perhaps the most well-known obsidian source in the Greater Yellowstone Area is Obsidian Cliff. The glassy cliff exposure of this source visible from the road rises 60 meters from the ground; the flow itself covers an area of approximately 14.5 square kilometers. It is a highly significant source at both the regional, national, and international levels. Artifacts made from obsidian from this source are found as widespread as Texas, Washington, southern Alberta, and Hopewellian burial mounds in Ohio, indicating it was a prized material extensively traded/exchanged (and directly accessed) by people for thousands of years. Large-scale archeological reconnaissance and survey of this source in the late 1980s culminated in its nomination as a National Historic Landmark.

Thanks to extensive sampling of the Obsidian Cliff flow, the geochemical composition of this source is known to cluster within an expected range and the geochemical integrity of the source has been well established. The Obsidian Cliff source locality is in the northwestern region of the park, to the east of the Gallatin Range and adjacent to the modern-day Mammoth to Norris section of the Grand Loop Road. This locality consists of an exposed cliff face (which is the feature popularly known as Obsidian Cliff or the Obsidian Cliff Plateau) and the flow area immediately east of the cliff face. There is evidence for both the utilization of cobbles as well as direct quarrying of the bedrock obsidian. Fifty-nine quarry pits/tool workshop locations were documented on the Obsidian Cliff Plateau, along with thousands of flakes and tools.

When visually inspected, Obsidian Cliff obsidian is glassy and smooth with few inclusions, and ranges in color from black to brown, mahogany, gray, and even green. It is typically semi-translucent in opacity, but infrequently can also be opaque. It is considered to be high-quality obsidian for tool making, particularly for knives and projectile points.

Many of the Native American tribes with ancestral or cultural associations with Yellowstone have indicated Obsidian Cliff is a spiritually and ideologically significant place, and have oral histories describing ancestral collection of obsidian from this place. In addition, medicinal use of obsidian from Yellowstone by more than one culture has been documented. This ethnographic information contributes to the overall cultural significance of what is also an exceptional archeological site.