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12 September 2011
“Clinker” is an interesting rock type seen in Wyoming’s Powder River Basin. It forms when a coal seam catches fire, and cooks the rock above and below it, including the potential for partially melting the strata immediately above. Check out a few images of this intriguing rock here.
29 June 2011
This year, for the first time ever, I took students to map at Block Mountain, a classic field camp mapping site near Dillon, Montana. Here’s a quick look (enlarge it by a gazillion-fold by clicking through) of some columnar jointing in the Eocene Block Mountain basalt flow, a paleo-drainage turned mountain through the miracle of topographic inversion… This is where it outcrops along the Burma Road… not bad at all.
9 March 2011
A few microscope photos for you, showing close-ups of feldspars in igneous dikes in the Crazy Mountains of Montana… You’ve seen these rocks before, when I posted a few field photos from this area in August 2009. I took these images of feldspar phenocrysts in a hand sample (from a quartz latite dike) with my no-longer-brand-new Nikon microscope camera: There’s some nice compositional zoning going on in some of these …
6 December 2010
The author recounts a field trip in October along the section of Turkey’s North Anatolian Fault that last ruptured in 1944. The rock types on either side of the fault are compared, offset markers are illustrated, and several types of landforms particular to strike-slip faults are shown. The post concludes with an examination of the town of Gerede itself, which is built directly atop the fault.