Named in 1879 by then Park Superintendent, P. W. Norris, Obsidian cliff runs south along Beaver Lake before turning east, continuing on for two more miles, and raising to a height of 200 feet above the earth.

While building a road along the side of the cliff in the previous year, Norris heated the obsidian with a fire and then rapidly cooled it, causing it to fracture. Crews used the fragments to form the world’s first and only “natural glass road.”

Formed 180,000 years ago when a rhyolite lava flow oozed onto the surface of the earth, it cooled very slowly, preventing the growth of crystals giving the obsidian its glassy sheen. There is academic debate over the exact nature of the formation of large volume rhyolite lava flows, like Obsidian Cliff, leading some authorities to conjecture that they formed out of dense pyroclastic flows of pumice and ash known as “rheomorphic ignimbrites.”

Obsidian Cliff was one of the largest Obsidian sources for Native Americans living in the area. The mechanical properties of obsidian and its brittle nature made it a useful material for Paleo-Indian cultures of North America.

Archaeologists believe Native people quarried the rock shortly after the end of the Ice Age in 10,000 B.C.E. Natives fashioned a number of devices including arrowheads, scrapers and spear tips from the obsidian. They prized the obsidian from Obsidian Cliff and traded it as far away as Ohio based on archaeological evidence from pre-Columbian burial grounds.

Researched, written, and narrated by University of West Florida Public History Student James Steele