Sopris geology lesson

Dear Editor:

I enjoyed reading the Times’ recent articles on the Roaring Fork River. The more we all know and understand our valley’s environment, the better we can appreciate and protect it. However, let’s keep the facts straight.

In “Reading the Roaring Fork,” Mount Sopris is referred to as a volcano that has spouted lava now found on the shores of the Fork. Though this is a pretty common misconception, it is way off base.

Ask any ninth-grade geology student in the local schools, and they can tell you it is actually an intrusive igneous feature known as a stock. The entire mountain was formed by an underground reservoir of magma, which cooled long before it reached the surface. Rather than forming any lava, this magma cooled slowly to form quartz monzonite.

The lava rock in the area is likely from the Basalt Mountain shield volcano just upstream. Sopris’ conical shape comes from glaciers and erosion.

Andre Wille

Aspen High School

Basalt