9 June 2017
Friday fold – or is it a fauxld?
Posted by Callan Bentley
Check this out: is it a fold?
Annotated to show the 3D expression of the ‘bed’ (left) and cross-sectional view (right):
Here’s a 3D model of the outcrop to better convey its shape:
This is in the same sandstone unit I blogged about on Tuesday with the apparent soft-sediment deformation. This could be another example of the same general class of pre-lithification structures, or it could be an optical illusion. Again it’s hard for me to make the call since the folded “layer” is the same composition as the layers above and below, yet if folded, it shows a significant rheological contrast. I don’t get it.
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.