cleavage

Another example of overturned bedding

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One of my favorite tricks is using bedding / cleavage intersections to identify tectonically inverted strata. On a field trip yesterday to check out soapstone quarries in the Albemarle/Nelson border region, I got to see this lovely example of Lynchburg Group metasediments that showcased a textbook example of the phenomenon: Bedding was initially horizontal, or … Read more

Friday folds from the Foreknobs Formation

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TGIF! That’s my seven year old field assistant showing off the shape of a syncline in shale, siltstone, and fine sandstone of the Foreknobs Formation, a Devonian nearshore package of clastic sediment in the Valley & Ridge Province of eastern West Virginia. Want to see something freaky for Halloween? Photoshop can make it happen: Ewwww. … Read more

Friday fold: Wiltondale, Newfoundland

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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 … Read more

Friday fold: kinked cleavage at Harpers Ferry

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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 … Read more

Friday fold: the anticline at Chickie’s Rock

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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 … Read more

Cleaved, boudinaged, folded Edinburg Formation southwest of Lexington

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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!

Cleavage refraction in Konnarock Fm. rhythmites – a virtual sample

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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 … Read more

Friday fold: Crumpled Dinwoody Formation, Sheep Mountain, Wyoming

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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 … Read more

Bedding/cleavage GigaPans at Harpers Ferry, WV

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I’ve been thinking lately about Harpers Ferry, the spot where West Virginia, Virginia, and Maryland meet, at the confluence of the Potomac River and the Shenandoah River. I’ve noted small outcrops of its overturned beddding here previously, and also described a book I read about the man who made the place infamous: John Brown. I … Read more

Friday fold: Apennine crenulation cleavage

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My new social media buddy Samuele Jæger Papeschi and I collaborated on some goofy maps in August, but then he noticed my Friday folds, and like the very best human beings anywhere, Samuele offered to pitch in with a few folds of his own. (Other readers are encouraged to do the same!) Today, I’ll feature the first … Read more