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18 March 2019

New discoveries in the Martinsburg Formation

A virtual field trip to examine some deepwater clastic sediments shed off the first phase of Appalachian mountain building, and deformed in the third phase. It’s a lovely day for a field trip to the late Ordovician!

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8 February 2019

Friday fold: Falte an der Riedbergpaßstraße im Allgäu

A Friday fold from Germany showing an overturned sequence of sedimentary layers. Bedding / cleavage relationships show which limb is tectonically inverted. Furthermore, this fold was an “Aha!” moment for the budding geological mind of a small boy.

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22 August 2018

Q&A, episode 5

A reader asks: “What is foliation and what makes it so important to the structure of rock?”
Callan answers with a lot of images of beautifully foliated rocks.

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15 July 2018

Chickie’s Rock, Pennsylvania

A virtual field trip to the deformed quartzites and metaconglomerates of Chickie’s Rock and Sam Lewis State Park in Lancaster County, Pennsylvania.

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13 July 2018

Friday fold: the anticline at Chickie’s Rock

Chickie’s Rock is a prominent cliff of Cambrian quartz arenite (sandstone) in Lancaster County, Pennsylvania. I visited it last month with field trippers at the eastern section meeting of the National Association of Geoscience Teachers. One of the aspects of the site is this gentle anticline with axial planar cleavage: The yellow rectangle is my field notebook for scale. Another shot: Happy Friday to all!

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13 February 2018

S-C fabric in limestone, Camerino, Italy

Some scaly Italian limestone shows off two foliations (S and C) which reveal the kinematic motions that built the Apennines.

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21 July 2017

Friday fold: Sardinia

My friend Ander Sundell at the College of Western Idaho is the source of today’s Friday fold. It’s from somewhere in Sardinia, and I think you’ll find it visually striking: Ander says: The rocks here are Silurian phyllites generated from mudstones that were deposited on the floor of the rheic ocean basin. The color and grain size variation do an excellent job highlighting compositional layering. They were deformed during the …

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27 March 2017

Cleaved, boudinaged, folded Edinburg Formation southwest of Lexington

Explore a dozen photos highlighting the structural geology of an outcrop of limestone and shale near Lexington, Virginia. Cleavage refraction, overturned beds, boudinage, folds, and even a small fossil – we’ve got something for everyone. Bring the whole family!

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6 June 2016

Cleavage refraction in Konnarock Fm. rhythmites – a virtual sample

Here’s a visualization combination that leverages the advantages of the GIGAmacro system with the 3D ‘virtual sample’ perspective of the Sketchfab-hosted model: the same sample presented in both formats. In this case, it’s a lovely example of cleavage refraction going from meta-clay-shale (now ‘slate’) through a graded bed of fine sand and silt. Link GIGAmacro by Callan Bentley Photoscan model by Marissa Dudek The sample is of the Neoproterozoic Konnarock …

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22 April 2016

Friday fold: Crumpled Dinwoody Formation, Sheep Mountain, Wyoming

Today for your folding pleasure, I give you two field GigaPans shot by Jeffrey Rollins, a two-time Rockies field course alumnus and Old Dominion University student working under my colleague Declan De Paor, assisted by NOVA student Bridget Gomez, during last summer’s extended GigaPan expedition at the Sheep Mountain Anticline, Wyoming. This particular outcrop was found near the axis of the massive Laramide fold, and shows an extensively deformed section …

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