30 November 2016
“Drumsticks” of Islay tillite
Posted by Callan Bentley
One fun thing about examining the Port Askaig Tillite in the field is to find odd-shaped exemplars of the unit lying on Islay’s beaches. My favorites were shaped like wands, or antennae, or perhaps the drumsticks freshly detached from a Thanksgiving turkey… a big clast at one end and then a thin septum of the finer-grained matrix to hang on to:
Here’s an example:
The shape results from differential weathering of the matrix relative to the large clast. Another example is perhaps even more striking, with an ice-cream-cone morphology:
I recently learned of a museum in Japan dedicated to rocks that look like faces. Perhaps some Ileach should found a museum dedicated to “drumstick stones”…
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.