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4 July 2014

Friday fold: Warspite Anticline

Friday fold: Warspite Anticline

A final guest Friday fold from reader Howard Allen, who I’m pleased to be meeting up with in Banff late next week… Howard writes the following in describing this lovely scene: Warspite Anticline, Peter Lougheed Provincial Park, Alberta. Photo is a telephoto shot (hence the strong blue alpine haze–the colour cast is an accurate rendition of the original daylight Kodachrome slide), looking southwest at an angle to regional strike. The …

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27 June 2014

Friday folds: Acadian metamorphics and pegmatite from coastal Maine

Friday folds: Acadian metamorphics and pegmatite from coastal Maine

Some folds this week from coastal exposures in western Boothbay Harbor, Maine, where I’m on vacation for one more day… Acadian metamorphics (schist, gneiss), with injected granite pegmatite that has also been folded (and boudinaged): Happy Friday!

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20 June 2014

Friday fold: the Castile Formation at the State line outcrop

Friday fold: the Castile Formation at the State line outcrop

The Friday fold visits the Permian basin of west Texas. There, the Castile Formation exhibits gorgeous inter- and intra-bed folding.

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13 June 2014

Friday fold: tortured turbidites at Devil’s Slide

Friday fold: tortured turbidites at Devil's Slide

Marek Cichanski (of De Anza College near the south end of San Francisco Bay) contributed this week’s Friday fold: Marek says: The locality is a place near San Francisco called Devils Slide. It is a piece of the coastal highway built along a steep mountainside above the ocean. This unstable stretch of road was recently (finally!) replaced by some tunnels. And, amazingly, the old roadbed finally got converted to a …

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6 June 2014

Friday fold: differential weathering of carbonate intraclasts in mudstone

Friday fold: differential weathering of carbonate intraclasts in mudstone

Howard Allen is the documentarian of this week’s fold: Howard writes that this is: Middle Cambrian Chancellor Formation rock with recessive weathering intraclasts(?). Hamilton Lake trail, Yoho National Park, British Columbia. My interpretation of this one is a little shaky–it was raining when I took the photo (in 1982) and I was hiking with a non-geologist friend, so I didn’t linger at the outcrop or record the precise location. I …

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30 May 2014

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

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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16 May 2014

Friday fold: Lyautey Syncline

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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9 May 2014

Friday fold: knuckling under in the Mesilla Valley shale

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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2 May 2014

Friday fauxld: Pennsylvanian plant fossil

Friday fauxld: Pennsylvanian plant fossil

Have a gander at this: Given that this is a Friday on Mountain Beltway,  you might expect to see a fold here, and indeed, there’s something wavy and high-contrast running through the center of this sample. But that’s no fold. It’s a fossil plant! A “reed” of some kind, I guess. You can also see a small fern frond in the lower right. This is a sample of the Pennsylvanian-aged …

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25 April 2014

Friday fold: Paw Paw Tunnel anticline

Friday fold: Paw Paw Tunnel anticline

As with last week, the Friday fold comes from my Field Studies in Geology class to Sideling Hill and the Paw Paw Tunnel. This is a view of the downstream (north) entrance to the Tunnel, with students highlighting the trace of bedding in the turbidites of the Brallier Formation: Can’t make it all out? Let’s try zooming in, and laying on some annotation: Happy Friday!

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