Callan Bentley 
Walking back to my hotel after departing the Northeastern / North-central GSA section meeting on Sunday, I noticed this fine shear band cutting across a polished slab of granite on the exterior of an office building in downtown Pittsburgh: You’ll notice some grain-size reduction along that shear zone, and what looks to be a decent … Read more
Saw this beauty on a field trip Saturday, examining the glacial geology of western Pennsylvania. Note the faceted surfaces and profusion of scratches of multiple sizes in multiple orientations.
The Shenandoah Valley of western Virginia records the switch in late Ordovician time from passive margin sedimentation associated with the Sauk and Tippecanoe epeiric seas, to active margin sedimentation associated with the onset of the Taconian Orogeny to the east. Higher up in the stack, a similar pattern is seen: a return to passive margin … Read more
Migmatite schist sample from Orange Springs Farm, near Unionville, Virginia, with cm-demarcated pencil for scale. Sample was cut and polished. Here’s what the untreated sample looks like: [youtube=http://www.youtube.com/watch?v=XDDcLVp_4Ss] Happy Friday. Enjoy your weekend. I’m off to the Northeastern / North-Central joint section meeting of the Geological Society of America today. We’ll see if my time … Read more
After my cousin Brad caught up with us after our Pinkham Notch roadcut excursion, we started up the trail at Tuckerman Ravine, and then detoured to go via the Lion Head. Immediately, we began to see some freaking awesome metamorphic porphyroblasts. During the Acadian Orogeny (in the late Devonian), the original muds and sands (deep … Read more
A new poll by Gallup suggests that the proportion of the U.S. population concerned about climate change has dropped to an almost record low (51% of the “polled population worrying about climate change a great deal/fair amount”). The data are interesting to look at: (source) I thought I detected a little pattern here with the … Read more
Just wanted to call your attention to two new maps showing GPS displacement vectors from Japan. (Barry left links to these images in a comment yesterday.) These images are hosted on the website of the Geospatial Information Authority of Japan, and though I can’t read the Japanese to verify their authorship, I presume that agency … Read more
Background geology of the Sugarloaf Mountain area. (March 2010) Primary structures in the meta-sandstone of the Sugarloaf Mountain Quartzite. (yesterday) Background on tension gashes. (August 2010)
You’ll recall that I detailed a trip to Sugarloaf on this blog back in March of last year. Well, on Saturday (March of this year), Lily and I returned to this distinctive knob of quartzite for a five-mile hike. Along the way, we saw plenty of metamorphosed quartz sandstone (now quartzite), which was similar to … Read more
Earthquakes themselves are rarely directly responsible for deaths… If you’re out in a field, or a park, it’s a disorienting experience, and you may see some weird stuff, but you’re not likely to be killed via whiplash. Usually, casualties are induced due to the collapse of buildings, or roads, bridges, tunnels, or other infrastructure failing … Read more
A new resource for the Japanese earthquake is online this morning, a “supersite” similar to the ones that exist for other huge events. Checking it out this morning, I found some interesting stuff. Over night, there have been more aftershocks, and here’s the most recent 600 or so events in the area, taken from IRIS’s … Read more
Something occurred to me this morning when I saw this: (source) …And it was this: (source) Do you think it’s a coincidence that NOAA’s mapmaker chose that particular royal blue / sky blue / white color scheme, augmented by gray continents with yellow accents? I suspect it’s a beautiful shout-out to the classic piece of … Read more
More from Mount Washington, New Hampshire: some folds in the Madison Member of the Littleton Formation (schist) along the auto road near Cragway Springs (just past 5 miles up; see map below): IMAGE SOURCE The folds are asymmetrical, with long west-dipping limbs, and shorter east-dipping limbs. Happy Friday!
I’m not usually the “report on current events” type of geoblogger, but someone needs to throw a few details up ASAP for those who are interested in the details of the big Japanese earthquake and resulting tsunami that is currently crossing the Pacific Ocean. First off: links to other geoblogs already reporting on the event: … Read more
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 … Read more
Friday’s prompt to post the French Thrust shot gave me the opportunity to dig into my “Rockies” folder a bit. Here’s two other shots from my inaugural summer leading my Geology 295 field class out there. Hiking the trail to Grinnell Glacier: …It looks like we’re in the Appekunny Formation here, third from the bottom … Read more
I’ve been reading some books lately about atheism. Though I’ve been a functional atheist for many years, I’ve been paying more attention to it lately in light of religiously-inspired idiocy from around the globe. I’ve become convinced that religious belief does more harm than good, and my sense of incredulity has deepened at how far … Read more
That title sounds kinky, right? Well, calm down. I’m behind the curve on the latest Accretionary Wedge (as I was for the one before that), but here’s a quick image to join the parade of geologic photos that Ann is hosting. While it’s not my favorite, it’s definitely a favorite, more by virtue of the … Read more
Took a hike this morning with my bride-to-be, out to Buzzard Rock on the northeastern corner of Massanutten Mountain. There, we observed numerous boulders of Massanutten Sandstone float, many bearing charismatic cross-beds. Here’s one more slab of float, presumably weathered out along the main bed, showing gorgeous internal cross-stratification: A closer look at the left … Read more