An ancient supervolcano helped shape Mineral County's mountains

The dramatic peaks and pale cliffs around Creede are not just pretty scenery. They are the leftovers of volcanoes. Volcanic activity in this part of the San Juan Mountains began roughly 35 million years ago, and the eruptions that followed left behind a cluster of collapsed volcanic basins called calderas. One of the biggest blasts came from the La Garita supervolcano, which erupted about 28 million years ago. Its huge collapsed basin and the La Garita Mountains lie to the south and west of Creede, while the town itself sits at the edge of a later, smaller one, the Creede Caldera.

Knowing this helps the landscape make sense. The thick layers of hardened volcanic ash, called tuff, are what the weather has carved into the spires of the Wheeler Geologic Area. The same volcanic past is also why the hills here held silver and other minerals, which is why mining came at all.

For a newcomer, the practical takeaway is gentler than it sounds. This is old, settled geology, not an active volcano. But the volcanic rock does shape steep terrain, loose slopes, and the way water and minerals move through the ground, which matters for building, roads, and old mine sites.

If you want to understand the rock under your feet here, the Rio Grande National Forest’s geology pages and the Colorado Geological Survey both describe the area’s volcanic story.