Cerro Del Medio

Antler in Obsidian Valley

NPS

Cerro del Medio began erupting approximately 1.1 million years ago and continued for about 25,000 years. Its lava flows created very high-quality obsidian for human use. A very sharp and shiny black rock, obsidian can be fashioned or “knapped” into tools, spear points, and arrowheads. It was also used as a form of currency, traded across long distances in the Americas.