Pisolites are large primary concretions that develop in backreef or lagoonal settings such as the Permian Tansil Formation of New Mexico, into which is cut the enormous hole called Carlsbad Caverns.
To continue with the karst theme I initiated yesterday, let me share a few photos today from a visit last week to Luray Caverns, a large show cave in Page County, Virginia near the town of Luray. This was my first visit to Luray Caverns since I was a child. Probably it had been thirty … Read more
Take a look at this… Doesn’t look like much, does it? But it’s actually the surface expression of a vast, long-lived sinkhole. If you walk over to the hole and look in, you can’t see the bottom. It’s semi-supported by limestone boulders, but between the boulders, the soil and gravel filter down, down, down, like … Read more
Had this brainstorm a few weeks back (or maybe months?). Been meaning to blog it up, but hadn’t gotten the chance to flesh it out. The geologic map of the Commonwealth comes from Chuck Bailey of William & Mary, who gave me permission to use it for this project. Anyhow – do you think there … Read more
My friend Dave Auldridge, formerly a structural geology student of mine at George Mason University, is now in grad school at the University of Alabama. Dave is working on an interesting project with speleothems: those drippy looking CaCO3 growths that you find in caves, like stalactites and stalagmites. He’s looking at these speleothems in order … Read more
I spent last Thursday on a long field trip in the Valley and Ridge province of northernwestern Virginia. Leading the trip was Dan Doctor of the USGS-Reston. Accompanying Dan was a UVA environmental science student named Nathan. And the NOVA crew rounded it out: professor Ken Rasmussen from the Annandale campus, associate professor Victor Zabielski … Read more