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6 November 2013
Natural Bridge, Yoho National Park: Bedding/cleavage relationships
Check out the scene at Natural Bridge in Yoho National Park, British Columbia, Canada: Don’t confuse this “Natural Bridge” with the one in Virginia. Here, in the western Canadian Rockies, the structural geology is much better. You may recall that I’ve previously featured outcrops from nearby this site as a Friday fold. It’s a great place for examining bedding / cleavage relationships in the rocks. Here’s the previous picture, annotated: …
23 April 2013
Return to the Outdoor Lab
Two years ago, I took a trip to the Phoebe Hall Knipling Outdoor Lab, which is Arlington, Virginia’s outdoor education facility in the Pond Mountains (southern continuation of the Bull Run Mountains), on the eastern edge of the Blue Ridge geologic province. I was invited back last week to look at some new exposures. I brought the GigaPan along. There had been additional erosion on the saprolitic exposure of Harpers …
5 April 2013
Two new GigaPans of Rockfish Gap, Virginia
I took a trip down to Charlottesville this week for a couple of meetings, and I made time along the way to capture two new GigaPans of the lovely exposures of Catoctin Formation greenstone at Rockfish Gap, where Interstate 64 traverses the Blue Ridge. This is very close to the southernmost tip of Shenandoah National Park, and at the northern terminus of the Blue Ridge Parkway. The Catoctin is an …
2 April 2013
GigaPan suite from the South Page Valley Martinsburg Outcrop
Are you into structure? Sedimentology? Stratigraphy? Well, I’ve got some good news for you – I’ve imaged several key outcrops on the newly-discovered (to me) roadcut on South Page Valley Road, showcasing the middle Martinsburg Formation turbidites (and their Alleghanian structural overprint). link link link link link link See if you can find: an anticline a syncline a fault a trace fossil a tool mark a graded bed cleavage refraction …
29 March 2013
Friday fold: “V”
The Friday fold photo was taken this morning on a GigaPanning expedition, and shows a small syncline within turbidite strata of the Martinsburg Formation, Page Valley, Virginia.
20 March 2013
Upper Martinsburg “Cub Sandstone” in GigaPan
Today, two GigaPans shot of the uppermost Martinsburg Formation, informally known as the “Cub Sandstone” since it crops out along Cub Run in the southern part of the Massanutten range. 10 or 15 meters upsection (west) of these two outcrops is the base of the Silurian-aged Massanutten Sandstone, the ridge-forming unit. Lower in the section: link Higher in the section: link If you explore these GigaPans, you’ll find a trend …
19 March 2013
A closer look at the recumbent anticline from last Friday
Last week, the Friday fold was presented in GigaPan format only, which led to a concerned reader lamenting that he couldn’t see it on his mobile device. (GigaPans are Flash-based images; they don’t work on Apple devices in the standard GigaPan format, though there is a perfectly suitable workaround with two extra clicks.) So, for the sake of this poor reader, who would otherwise be denied a view of this …
15 March 2013
Friday fold: a recumbent anticline in an abandoned quarry
Yesterday, I spent a pleasant day in the field with John Singleton, the new structural geology professor at George Mason University. I was showing John a couple of sites I’ve used as field trip locations for the GMU structural geology class, and John was showing a couple of new sites to me – places he visited on last fall’s Virginia Geological Field Conference. I missed VGFC last fall, as I …
Giant pencil cleavage in the Martinsburg Formation
Two giant “pencils” in the Martinsburg Formation: You can see smaller (more typically sized) “pencils” on the slope behind me. Photo by John Singleton, GMU.
8 March 2013
Friday fold: Fault propagation fold from Cristo Rey
The Friday fold comes from the Texas – New Mexico – Chihuahua triple point, on the flanks of Cristo Rey mountain.
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.