7 October 2016
Friday folds: Dalradian schists at St. Ninian’s Isle
Posted by Callan Bentley
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 broken into segments, and the segments have separated from one another along the plane of foliation. Note how the foliation deflects into the boudin neck from each side:
Annotated version:
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.