is the site of one of the largest volcanic eruptions in Earth’s history approximately 28 million years ago (Eocene). That enormous geologic event has left quite a bruise on south central Colorado and also created rich mineral deposits in the region.
Oblique aerial view towards the north showing the 20 mile wide (32 km) La Garita Caldera structure from Google Earth. Snowshoe Mountain is a resurgent dome in the core of the caldera.
The upper Rio Grande Valley on the western side of the La Garita caldera.
Much of the valley bottom is mantled with glacial till in terminal and lateral moraines and with glacial outwash.
Bristol Head mountain stands at 12,712 feet (3,875 meters) high with a smaller resurgent dome on the left.
Caldera-filling sedimentary rocks of the Creede Formation (Oligocene) near Creede, Colorado reflecting a lacustrine environment of deposition.