Geology Tour

I'm pleased to see that The Watch, a weekly newspaper covering Telluride, Ouray, and Ridgway, included some of my comments on the wonderful geology tour sponsored by the Ouray County Historical Society last week.

Here's the link:

http://www.thewatchmedia.com/tour-symposium-plumb-riches-of-ourays-geology/

Red Mountain, whose color is caused by hydrothermic gas and water oxidizing iron in the debris that fell back into the caldera after the Silverton supervolcano exploded about 26 million years ago.  Nearby mountains are grey, formed from orderly layers of volcanic ash outside the caldera, which resisted intrusion of gas and water.