Lone rock towers near La Veta are old volcanic plugs

Driving the valleys around La Veta, you may notice a steep, lone rock tower standing up out of otherwise gentle ground. Goemmer Butte, near La Veta, is the best-known example. Features like this are often the hardened core of an old volcanic vent, sometimes called a plug or neck. Long ago molten rock filled the throat of a vent and cooled into very hard stone. Over millions of years the softer ground around it eroded away, and the tough plug was left standing.

These plugs are cousins to the long stone dikes that radiate out from the nearby Spanish Peaks. They are part of the same story of molten rock pushing up through this corner of Colorado and then being exposed by erosion.

Why it matters beyond the scenery: many of these landmarks sit on private ranch land, so a striking rock you can see from the road is not always a place you can walk up to. They also make handy reference points for describing a parcel or finding a turn. Knowing one is a volcanic plug, not just a “hill,” tells you something about the durable, rocky ground around it.

For the geology of these features, the Colorado Geological Survey is a good place to start, and access to any specific butte depends on who owns the land.