Sunday, March 18, 2012
Strangers in a Strange Land: The Value of a Road Cut
But even here, where the climate is so dry that plants can scarcely survive, the rocks are still obscured. The geologists who have training in field methods can make sense of this sort of landscape, but students who are in the field for the first time can feel intimidated. A few gray rocks in the foreground, some tan colored rocks across the small valley, and a difficult time understanding how they relate to each other. It would be a challenge. But once in a while, the department of transportation does us a real favor. They want to make their roads straighter, and when nature hasn't cooperated by eroding into straight lines, they make roadcuts for us.
For instance, if the scene shown above doesn't look all that remarkable, look what happens when you turn around...
So, what would you do with your students here?
Oh, and by the way, all you mineralogists out there, what do you think this nice botryoidal mineral might be? I have my strong suspicions about a relatively simple answer, but I've just assumed it for a long time. The host rock is a rhyolite tuff, and hot vapors and groundwater have probably both influenced the outcrop.