Friday fold: Mosaic Canyon Monster

While out in Death Valley with my Field Studies students last March, we encountered an extraordinary fold in Mosaic Canyon. Check this thing out: The rock is the Noonday Dolostone (“Noonday Dolomite” in mineralogically biased argot). It may be hard to make out what’s what there… So let me assist with a little annotation, tracing … Read more

Vulture petroglyph from Castle Gardens, Wyoming

Happy new year! Time marches on – and here’s a reminder of times past… Check this out – a couple of what appear to be vultures, etched by native Americans into the siltstone at Castle Gardens, Wyoming: Diameter of the outer circle is probably 1.5 or 2 feet. My annotated (and generally embelished) version: I … Read more

Migmacatization

Evelyn put up a cat photo on Geokittehs earlier today, and it reminded me of anatexis, the process of partial melting. Anatexis is my favorite way to produce a migmatite. In this model, the light-colored (felsic) ginger cat is derived from the partial melting of another cat, partly dark (mafic) and partly felsic (ginger). Where … Read more

“Got migmatite?”

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