photo: Lon Abbott and Terri Cook
Southwestern Colorado’s San Juan Mountain range is made up of the eroded remnants of dozens of volcanoes that were erupting between 35-25 million years ago. This includes the world’s largest volcanic caldera, whose violent eruption 28 million years ago spewed enough volcanic ash to cover the entire state of California in ash almost 40 feet deep!
photo: Lon Abbott and Terri Cook