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30 July 2022
Well-preserved mudcracks in Belt argillite, Glacier National Park, Montana
Fresh from the field, Callan shares a quintet of beautifully preserved desiccation cracks in Mesoproterozoic Belt Supergroups sediments, exposed in Montana’s geological gem, Glacier National Park.
24 June 2022
Friday fold: Kinked Lynchburg metasediments near a soapstone body
Happy Friday! Here are some kink-folded metasediments from Virginia’s Lynchburg Group to help usher in the weekend.
21 June 2022
Another example of overturned bedding
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 close to it, and cleavage (formed under tectonic compression) initially vertical. Subsequent deformation rotated the …
25 June 2021
Friday fold: The Blue Ridge Tunnel
Inside the Blue Ridge (in an 1850s-era railroad tunnel), Callan finds folds and boudinage that formed during Appalachian mountain-building.
7 May 2021
Friday fold: Lynchburg Group
On his way to get his COVID vaccine, Callan visits a new outcrop showing folded and faulted strata of the Neoproterozoic Lynchburg Group.
16 April 2021
Friday fold: Colorado cluster
Friday means folds –
This week, we head to the Colorado Rockies for a butterfly-like presentation of a ptygmaticly folded granite dike within biotite schist.
22 May 2020
Friday fold: Anticline in Glacier National Park
Some web research led to a serendipitous discovery and further exploration. Wherever you’re sheltering in place, you don’t have a view that’s this grand. Slip away for a few moments to the high country of Montana’s Glacier National Park, where an anticline may be seen in the towering cliffs…
22 November 2019
Friday fold: Noonday Dolomite in Mosaic Canyon
Because I’m putting together a field course for spring break 2020 to Death Valley California, I was looking through old Death Valley photos this week, from the last time I went to that special place. It was seven years ago! How time flies… This one is in Mosaic Canyon, and was taken by my student Marcelo Arispe, a talented photographer as well as a talented geologist: By the standards of …
11 October 2019
Friday fold: Watern Cove
A moderate mesoscale monocline at Watern Cove, Newfoundland, shows off multicellular animal fossils of the Ediacaran Mistaken Point Formation.
11 July 2019
A submarine slump complex at Sandy Cove, Newfoundland
Traveling in Newfoundland, Callan visits a seaside outcrop showing a Proterozoic submarine slump complex, overprinted by tectonic cleavage and weathered by the sea.
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.