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You are browsing the archive for May 2014 - Mountain Beltway.

30 May 2014

Friday fold: subthrust syncline in lower Helderberg limestones, Corridor H

Click to enlarge You owe it to yourself to click through and make this bigger. Check out the prominent lower left to upper right thrust fault, and the shattering in the shorter limb of the underlying syncline. Is that another one to the right? Happy exploring, and happy Friday!

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29 May 2014

A new diamictite exposure (Devonian?) along Corridor H

While on Corridor H last week with Team “Border to Beltway” (and USGS research geologist Dan Doctor), we stopped at the putative mass transport deposit. We still haven’t figured out which unit this is (It’s not the Foreknobs), but as we approached it, Dan wondered aloud, “I wonder where the top of the Devonian is. Maybe we could find some of Dave Brezinski’s glacial deposits.” If you’re not aware of …

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28 May 2014

B2B Coastal Plain trip

Last week, the “Border to Beltway” field exchange team went to Dora Kelly Park in Alexandria, Virginia. There, a ravine reveals the boundary between the Coastal Plain and the underlying metamorphic rocks of the Piedmont… My NOVA colleague Ken Rasmussen joined us for the day, leading us deep below the soil profile to examine the basal nonconformity beneath our youngest geologic province: The ravine was dark, so the next few …

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18 May 2014

B2B 2: the mid-Atlantic phase

Folks, I’m off to lead another field course – so don’t expect much on the blog this week. This is “phase 2” of the Border to Beltway community college field exchange program. In March, over spring break, I took a dozen NOVA students to Texas to team up with a dozen students from El Paso Community College, and now it’s payback time. Our EPCC collaborators are on their way to …

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16 May 2014

Friday fold: Lyautey Syncline

Another guest Friday fold from Howard Allen: View looking north at Mount Lyautey, on axis of the Lyautey Syncline, from Aster Lake trail, Peter Lougheed Provincial Park, Alberta. Rocks are carbonates of the upper Mount Head Formation, Carboniferous (Mississippian). Photo taken in 1981.

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12 May 2014

How About Never — Is Never Good For You? by Bob Mankoff

My friend Joe Cancellare knows that I like cartoons, and that I even draw a few cartoons myself. He surprised me a couple weeks ago with a gift of a book – a new memoir by New Yorker cartoon editor Bob Mankoff. This was a real treat – it explores (a) the idea of how cartoons work (or don’t), (b) Mankoff’s own journey as a cartoonist, entrepreneur, and eventual editor, …

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9 May 2014

Friday fold: knuckling under in the Mesilla Valley shale

Here’s a fold I saw in Texas, in the Mesilla Valley shale, close to the contact with the Muleros Andesite at Cristo Rey: This is a pretty wild looking fold. Let’s zoom in on the most deformed portion: Annotation: white is top of the distinctive, blocky, buckled bed, and black is its bottom side. Red shows brittle fractures in that same bed: Looks as if it rolled over on itself …

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8 May 2014

Honey crystallization as an analogue for magma segregation and cumulate textures

Check this out: Maybe I’ve got low blood sugar, but I think I see a magma chamber in that jar of honey. There is clearly some crystal settling going on there, and it appears that the more crystals there are, the easier it is to trap bubbles. When the clots of crystals get too dense, they peel off (stope) and drop down to the floor of the jar. Similar sorting …

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7 May 2014

Bedding / cleavage relationships in the Edinburg Formation

Here’s a little scene along Route 340 / 522, north of Front Royal and south of Double Tollgate, Virginia, in the Shenandoah Valley: The rock here is limestone and shale of the Edinburg Formation, a late Ordovician unit that records the transition from passive margin sedimentation to the increasingly ‘dirty’ clastic influence of the Taconian Orogeny. Have a look: I hope you’ll notice there are layers of two distinct lithologies …

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6 May 2014

McKittrick Canyon, Guadalupe Mountains National Park, Texas

While in West Texas over spring break, the “Border to Beltway” students took a hike up McKittrick Canyon, in Guadalupe Mountains National Park. This is part of the famed Permian reef complex, the deep reservoir of Texas’s rich endowment of oil. Here, the reef comes to the surface. In fact, it pokes up a good bit into the air: Can you see it? If not, let Marcelo, Robin, and Nicole …

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