Obsidian Cliffs obsidian (Oregon Cascades)

Obsidian Cliffs is an obsidian source on the west flank of North Sister in the Oregon High Cascades, in Lane County within the Three Sisters Wilderness. The Northwest Research Obsidian Studies Laboratory calls it one of Oregon's most intensively used prehistoric glass sources, and maps it as part of a rhyodacite and dacite unit. Artifacts of this glass are known from 550 sites in Oregon, Washington and British Columbia. It was carried mostly north: it makes up about 85 percent of obsidian at sites in the McKenzie River subbasin and 72 percent in the Clackamas and Santiam subbasins, but only 8 percent in the Umpqua Basin to the south. At Cascadia Cave 96 percent of the characterized obsidian is from Obsidian Cliffs. Use extends back at least 11,000 years.

Mapped as part of unit Qr (rhyodacite and dacite) by Taylor and others 1987, on the west flank of North Sister in the High Cascades. The source plateau is limited by snow in winter, and entry to it requires a special permit.