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3 January 2018
An odd mystery rock from Shetland
Any readers have any idea what this strange rock is? It’s got wild patterns! These samples were in the garden of a local rockhound in Lerwick; I have zero idea what the mineralogy is; I was just stunned by the “scale-like” pattern of gray and pink. I’d be eager to hear your ideas what this might be. Thanks very much in advance!
3 May 2017
Storm beaches have I loved
The answer to yesterday’s geo-puzzle is revealed to be a storm deposit of boulders, 20 m above sea level!
3 March 2017
Friday fold: Kink folded Dalradian metasediments
Let’s reminisce back to the Walls Boundary Fault on the Ollaberry Peninsula of Shetland today. Here’s a 3D model to go along with the ones I posted last time: It’s a little ragged, but so am I at the end of the workweek! Happy Friday. Have fun spinning this thing.
2 March 2017
A virtual field trip to the Grind of the Navir
On the northwestern coast of the Northmavine Peninsula of Shetland, there is an unusual coastal landform: a gate-like entrance to an elevated amphitheater, like something out of Tolkien, and a storm beach of slab-like boulders inland of that.
1 February 2017
An oddball at Eshaness
In eastern Shetland, the sea chews away at the innards of a Devonian stratovolcano. But there’s an odd visitor there too – and we’re not talking about the blogger.
26 January 2017
Dore Holm
The scenic arch of Dore Holm (“Door Island”) in Shetland shows off the most efficient way of breaking a slab of rock. The island’s shape is a reflection of the parsimonious nature of natural deformation.
7 October 2016
Friday folds: Dalradian schists at St. Ninian’s Isle
Remember St. Ninian’s Isle? It is connected to Mainland Shetland by a tombolo. But it has rocks there, too. Here are some outcrops on the beach: If you visit these schisty fins, you’ll find they are populated by a cavalcade of small folds. Some of the folds are crisp things known as kink bands: Annotated version: And finally, as a lagniappe, here’s a bit of boudinage. This quartz vein has …
7 July 2016
Tombolo at St. Ninian’s Isle, Shetland
I came to Shetland for the rocks – but I’ve been surprised and delighted by the huge range of interesting coastal geomorphology to be seen here too. I’ve never seen so many sea stacks, wave-cut cliffs, and bayhead bars in my life. One that is so “classic,” so “textbook” that I couldn’t resist it, is the tombolo that connects St. Ninian’s Isle to mainland Shetland. In Google maps, it couldn’t …
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.