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 ...

Mount Sneffels in the San Juan Mountains Extreme mountaineer Hilaree O'Neil climbing in the San Juan Mountains, Mount Sneffels Hilaree climbs and skis the most challenging of mountains in the Rockies.