Callan @callan-bentley ?active 1 hour, 17 minutes ago
Callan wrote a new post, Virginia Museum of Natural History specimens in GIGAmacro view, on the site Mountain Beltway 1 hour, 26 minutes ago
One of the small sub-projects of my 2015-2017 Chancellor’s Commonwealth Professorship is to create some GIGAmacro images of cool fossil specimens from the Virginia Museum of Natural History in Martinsville. […]
I probably should have read this book eight years ago when it was first published, but somehow I missed it then. I recently heard the author, Susan Jacoby, on the podcast Point of Inquiry, and was impressed at […]
Callan wrote a new post, Friday fold: Shetland geopark rock wall at Northmavine, on the site Mountain Beltway 5 days, 4 hours ago
Here’s our Friday fold: a rock wall constructed as part of Geopark Shetland, right at a skinny little isthmus between the main part of mainland Shetland and the peninsula called Northmavine:
Click to […]
One of the final outcrops I visited this summer in Shetland was a sweet exposure of augen gneiss in eastern “mainland.” Augen is from the German for “eyes” and refers to the sheared-out feldspars. If you stare […]
Based on this photo, what do you think Stađarbjargavík might have to offer?
If you guessed columnar jointing in basalt, you’d be right!
Looking down the fjord, south of Hofsós (in Ic […]
Callan wrote a new post, A virtual field trip to examine the Peninsula Sandstone on Table Mountain, on the site Mountain Beltway 1 week, 1 day ago
Today, we’ll take a look at some immersive digital imagery I made on a hike up Table Mountain’s Platteklip Gorge while attending the International Geological Congress a few weeks ago.
Here is the northern edge […]
Callan wrote a new post, Geopoetry: a short recounting of Virginia’s long history, on the site Mountain Beltway 1 week, 2 days ago
…And now for something completely different!
This past weekend, my family gathered in Capon Springs, West Virginia, to celebrate my mother’s 70th birthday. She asked for an unusual birthday gift – an original […]
Those are some lovely ptygmatic folds in a migmatitic gneiss from Rocky Mountain National Park in Colorado. The age of the rock is apparently Mesoproterozoic. Bill Burton, who has shared Friday folds before, […]
Callan wrote a new post, Pillow basalts from eastern Washington: a 3D model, on the site Mountain Beltway 1 week, 6 days ago
Since I showed off some Icelandic pillow basalts yesterday, today I thought I would showcase a new 3D model of big pillows in Columbia River basalt of eastern Washington, taken from a photo set I made when I was […]
Time is short these days, but I know you hanker for amazing geology. How about some pillow basalts from the Snæfellsnes* Peninsula, far western Iceland?
Note the cm-demarcated pencil for scale. See if you […]
This is pretty wild: a peat slide in mainland Shetland:
One of the insights I had while travelling in Shetland this past summer was that peat doesn’t only grow in low-lying waterlogged bogs. It can also […]
Callan wrote a new post, Friday folds: A study in contrasts at the Walls Boundary Fault, Shetland, on the site Mountain Beltway 2 weeks, 4 days ago
Today, in search of folds, we head for a fault!
This is the Walls Boundary Fault, looking north along its trace near Ollaberry in mainland Shetland, U.K.:
Can’t see it? Here, let me help:
Callan wrote a new post, Tension gashes in Malmesbury metasediments near Sea Point Contact, on the site Mountain Beltway 2 weeks, 6 days ago
While en route to the Sea Point migmatite contact last week, I saw some lovely quartz-filled tension gashes in the Malmesbury Group metasediments adjacent to the contact with the Cape Granite. These en echelon […]
Lab Girl, by Hope Jahren, is a unique memoir. It describes Jahren’s journey through life from her childhood in the frigid northern Midwest to her eventual success as a celebrated scientist and an original t […]
Callan wrote a new post, Viewing the Sea Point migmatite through the lens of GigaPan, on the site Mountain Beltway 3 weeks, 4 days ago
It was five years ago when I first visited Sea Point, the outcrop on the coast of the Cape Peninsula where the Cape Granite (~540 Ma) intrudes the (meta-)sedimentary rocks of the Malmesbury Group. The outcrop […]
Callan wrote a new post, Friday fold: isoclinal fold in ferruginous pelite and chert of the Fig Tree Group, on the site Mountain Beltway 3 weeks, 5 days ago
A quick Friday fold – Ulundi Formation, basal Fig Tree Group of the Barberton Greenstone Belt, exposed in a creekbed etched into the trace of the Sheba Fault. This is one of the outcrops I visited one week ago […]
Yesterday, an article was published in Nature (Nutman, et al. 2016) announcing the discovery of what may be the oldest macroscopic fossils on Earth, some microbially-induced sedimentary structures (MISS) that show […]
Callan wrote a new post, Ball & pillow and other sedimentary structures in Graafwater Formation, Table Mountain, on the site Mountain Beltway 4 weeks ago
I hiked Table Mountain yesterday, south of Cape Town, via the notoriously steep Platteklip Gorge. I detoured a wee bit on the “contour trail” which heads toward Devil’s Peak to see some fine exposures of the […]
Callan wrote a new post, Northwest Highlands unconformities (3 of 3): Sub-Ardvreck, on the site Mountain Beltway 4 weeks, 1 day ago
It’s time to cover the third and final unconformity I observed this summer in the North-West Highlands of Scotland: the unconformity between the Neoproterozoic Torridonian Group below and the Cambrian Ardvreck […]
Callan wrote a new post, Northwest Highlands unconformities (2 of 3): Sub-Torridonian Group, on the site Mountain Beltway 1 month, 1 week ago
Let’s now profile the next unconformity in the sequence of pulses of erosion and deposition recorded in the North-West Highlands of Scotland. For a reminder, here’s a cartoon cross-section through the four […]
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