3 November 2017
Friday fold: More kinks from Glacier National Park
Posted by Callan Bentley
This Friday, let’s return to Glacier National Park. Here are some folds in Helena Formation limestone:
Can’t see them? Fair enough – the point of maximum inflection appears to be hidden behind a snow-filled gully:
But in addition to that big fold, there are several kink bands in there, too. Let’s zoom in:
Here they are:
Zooming in further, on the right-most of these kink bands:
…And here, with the traces of bedding highlighted:
These strata are Mesoproterozoic. The folding is probably Cretaceous or Paleogene in age (related to the Sevier Orogeny).
Deep time, rocks that tell stories with multiple chapters: Good fodder for a Friday fold!
Enjoy your weekend.
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.