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13 October 2017
Friday fold: ptygmatic vein from Finland (NMNH)
Happy Friday! Here’s a sample from the Smithsonian Institution’s National Museum of Natural History in DC: As the label says, we have a nice example of ptygmatic (“intestine like”) buckle folding here. It comes from Finland. The coarse equigranular crystals in the vein appear to be mainly potassium feldspar and quartz. The surrounding matrix has a pronounced foliation. Note the cuspate “flames” of matrix between the broad “lobes” of folded …
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.