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12 July 2019
Here is an outcrop of folded limestone along route 430 in Newfoundland, inside Gros Morne National Park, just west of the crossroads called Wiltondale: A detailed look at the left antiformal portion of the outcrop: A zoomed-in examination of the rightmost part, where a goopy looking synform resides: Just down the way, a second outcrop shows another fold with the same sense of asymmetry, on a smaller scale: Happy Friday …
11 July 2019
Traveling in Newfoundland, Callan visits a seaside outcrop showing a Proterozoic submarine slump complex, overprinted by tectonic cleavage and weathered by the sea.
14 June 2019
Last weekend was the annual meeting of the eastern section of the National Association of Geoscience Teachers. On Friday afternoon, we visited Harpers Ferry, West Virginia, and my colleague Beth Doyle led a great field trip to examine the rocks exposed there. This was my favorite outcrop we saw: Here is a close up of this outcrop, which is framed by (anthropogenic) rock wall: Dipping shallowly from upper left to …
18 March 2019
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!
8 February 2019
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.
22 August 2018
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.
15 July 2018
A virtual field trip to the deformed quartzites and metaconglomerates of Chickie’s Rock and Sam Lewis State Park in Lancaster County, Pennsylvania.
13 July 2018
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!
13 February 2018
Some scaly Italian limestone shows off two foliations (S and C) which reveal the kinematic motions that built the Apennines.
21 July 2017
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 …