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You are browsing the archive for March 2011 - Page 2 of 3 - Mountain Beltway.

21 March 2011

The Big Bentonite just got smaller

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 sedimentation with the deposition of the Helderberg Group of limestones, and then more active margin …

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18 March 2011

Friday fold: OSF migmatite

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: 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 in Pittsburgh gives me enough time to blog or not…

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17 March 2011

Mount Washington 3: turbidites and their metamorphism

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 sea turbidite deposits) of the Littleton Formation were metamorphosed. Pale-pink andalusite formed (that’s where these …

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16 March 2011

Video book review: Roadside Geology of Maryland, Delaware, and Washington, D.C. by John Means

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15 March 2011

Less U.S. concern for climate change

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 numbers waxing and waning, and so I went to NASA’s GISS dataset for the U.S. …

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New GPS vectors

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 produced them as well. They are easier to read than the one I posted on …

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Sugarloaf III: Tension gashes

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)

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14 March 2011

Sugarloaf II: Primary structures

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 what we saw on the previous Saturday’s hike, to Buzzard Rock on the northeast tip …

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12 March 2011

Secondary effects

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 due to being shaken by the seismic waves. Someone paraphrased the NRA yesterday with the …

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The morning after

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 interactive map. You can see the big circle that represents yesterday’s main shock: Explore the …

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