As part of my work on the GEODE project, I’m always looking for good imagery to teach key concepts in geoscience. One important concept that I’ve been thinking about lately is the principle of relative dating on the basis of inclusions. Just as you can’t bake a loaf of raisin bread without already having raisins … Read more
After reading the post last weekend about the discordant offshoot of the Purcell Sill, Rich Gashnig (post-doc at Georgia Tech) sent me a few photos he shot at Piegan Pass (at the head of a side-canyon adjacent to the one containing Grinnell Glacier). They show the Purcell Sill leaving one stratigraphic horizon and jumping to … Read more
I was in Tucson this past weekend for a book project meeting, and my editor and coauthor and I took a hike on Sunday morning in the Tucson Mountains to Wasson Peak. Not far from the summit, we saw an epidotized tuff, where the fiamme and pumice blobs had undergone reactions to produce pods of … Read more
As a follow-up to my post about the geology of the Acropolis klippe in Athens, Greece, and in the spirit of my post on the building stones of the Haghia Sophia in İstabul, Turkey, let’s turn our attention today to the various rocks that ancient Greeks used to construct the buildings of the Acropolis, such … Read more
Devonian metamorphic rocks (garnet-bearing gneiss) exposed on the western side of Cabbage Island, Maine: And here it is in GigaPan form: [gigapan id=”157674″] link
Happy Friday! Here’s some folded schistocity in the schist of Santorini’s Cycladean subduction complex: The blunt crest of the fold in the second photo appears to be a folded marble boudin. Neato!
As mentioned last week, I took a solo field trip north of Perissa, Santorini, Greece, in search of subducted rocks. The contact between the two main rock types (marble and schist) was prominent and visible from a great distance (see photos in previous post), but what was the nature of this contact? Did it represent … Read more
While in Santorini, Greece, your humble geoblogger braves a warm afternoon to search the hillsides for evidence of subduction.
A glimpse out an airplane window reveals some Cycladean geology in the Aegean Sea. Somewhere down there among the metamorphic rocks is our Friday fold… but nary a volcano in sight.
Over the weekend, I ran a 1-credit field course for NOVA, on the geology of Shenandoah National Park. I was about eight minutes early getting to the meet-up location, so that allowed me to check out a promising new outcrop of rock along the road (route 33, ~100 m west of Swift Run Gap). Here … Read more