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28 June 2016
“Dunbar marble” at Barns Ness, Scotland
Thanks to the website ScottishGeology.com, run by Angus Miller, I learned of Barns Ness, a Mississippian-aged limestone fossil site on the shore not far from where we are staying at Dunbar. We ventured out there on Saturday afternoon, in search of fossils. The presence of the Dunbar Cemenet Works nearby is an indication that this is the most extensive limestone outcrop in central Scotland. I set my field assistant loose …
25 June 2016
A virtual field trip to the Giant’s Causeway, Northern Ireland
Some of planet Earth’s best examples of basaltic cooling columns are found at the Giant’s Causeway in Northern Ireland. In this post, explore four different kinds of interactive digital media as a way of experiencing the Causeway virtually, from the comfort of your computer.
20 June 2016
Cushendun Conglomerate of the Cross Slieve Group, Northern Ireland
Want a geological irony? Here’s one! You’re looking at a rounded boulder of Cushendun Conglomerate, a Devonian “Old Red Sandstone” unit (Cross Slieve Group) exposed at Cushendun Caves, Northern Ireland, U.K. The irony lies in the repetition of history – a tumbling environment of high water energy, rounding cobbles and boulders and depositing them, in order to make the conglomerate. And now, ~400 million years later, history repeats itself, with …
19 June 2016
3D model of onion-skin weathering
I collected a photo set at the Giant’s Causeway to show the “textbook” examples of spheroidal (“onion skin”) weathering exposed on the road down to the causeway. My student Marissa Dudek used the photo set and Agisoft Photoscan to make a great 3D model of the site. She posted it on Sketchfab yesterday evening. Check it out! Photoscan model by Marissa Dudek Great work, Marissa!
8 June 2016
Differential weathering in dolostone – a virtual sample
Our series of virtual samples continues! This week, I’m presenting examples of 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. Today, we feature a differentially weathered dolostone. Link GIGAmacro by Callan Bentley Photoscan model by Marissa Dudek Differential weathering (i.e., different rates of weathering for different substances subject to the …
31 May 2016
A baked horizon in the Columbia River flood basalts
How did this bold orange layer develop? It’s seen in an outcrop near Wilson Creek, Washington, in the Columbia River basalts.
17 May 2016
Spheroidal weathering in Columbia River basalt
I’m in Idaho for the Rocky Mountain section meeting of the Geological Society of America. Yesterday, I was delighted to tour around in eastern Washington’s Channeled Scablands with my colleague Bill Richards (North Idaho College). I took a lot of photos, but here are two to start – lovely examples of “onion skin” style weathering in fractured basalt, producing “kernstones” of increasingly spherical shape: This is a particularly well expressed …
13 May 2016
Friday fold: 3D syncline in Macigno Formation
Alan Pitts is the source of today’s fold, a beautiful 3D model of a differentially-weathered sycline in the Late Oligocene to Early Miocene deep water Macigno Formation from western Tuscany, Italy. Here’s a photo: Now for the 3D model, hosted by Sketchfab; After it loads, use your mouse to grab this thing and finesse it around. What an outcrop! What a great 3D model! Thanks for sharing this, Alan!
15 March 2016
Timberville
Join Callan for a virtual field trip, as he shares dozens of photos from a recent ‘field review’ of a new geological map in Virginia’s Valley & Ridge province. Highlights: graptolites, trace fossils, geopetal structures, folds and faults.
15 January 2016
Friday fold: Harpers Ferry
The geology east of Harpers Ferry, West Virginia, is cool. It’s Blue Ridge rocks, from basement to the cover sequence, tilted to the west and broken and repeated by the Short Hill Fault. Here’s a look at a detail of the Geology of the Harpers Ferry quadrangle by Southworth and Brezinski (1996). So there’s a fault! Good – but the title of this post isn’t “Friday fault” – Where’s the …
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.