Where is Obsidian Cliff?

Obsidian Cliff is located in Yellowstone National Park, USA, just off of U.S. Highway 89, 13 miles south of Mammoth Hot Springs. It was an important source of stone tools for prehistoric peoples in the area. It was first quarried 11,000 years ago and tools from this cliff have been found as far away as Western Canada and Ohio. Unlike most obsidian which is found as small rocks amid other formations, Obsidian Cliff has a vertical thickness of up to 98 feet.

Obsidian is formed by a thick rhyolite lava flow and forms as the lava cools and crystallizes. Obsidian is a dark volcanic glass, and was used by early natives for sharp-edged tools since it can be honed to an exceptionally thin edge.

The cliff was named by Philetus Norris, the second YNP superintendent, in 1878. In 1996, it was declared a National Historic Landmark. The nearby kiosk, built in 1931, is the first wayside exhibit in a US National Park.