MK Thompson/San Juan Mountains Association MK Thompson/San Juan
Mountains Association Here in Southwest Colorado, we don’t often
think of volcanoes. Some might think of volcanoes as faraway
forces creating islands in oceans or billowing toxic smoke
across the skyline of some African city. But present-day
volcanic activity is taking place not very far away in places
such as Wyoming and Washington state. And volcanic activity once
was abundant in Southwest Colorado, perhaps right where you are
sitting. It helped shape many of the landforms in the area.
There are three main types of volcanoes as they appear on the
surface: shield volcanoes, composite cones and calderas. Shield
volcanoes form when free-flowing lava makes a low, shield-shaped
peak above ground. Composite cones are built up by a series of
thick flows and explosions. Calderas are large craters in the
ground created when either an explosion or an underground leak
drains the underground magma chamber. No two volcanoes are
alike, but all volcanoes form