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12 July 2011
Stylolites in Mississippian limestone
Stylolites (pressure solution seams) in limestone of Mississippian age, exposed on the side of a rounded boulder in Hyalite Canyon, Gallatin Range, Montana. These stylolites, like most, are bedding-parallel, and thus most likely formed due to the weight of the overlying rock. Calcite, the dominant mineral, goes into solution under pressure, and insoluble material, like organic matter and clay, accumulates along the dissolution surface, producing a dark, wiggly line. Here, …
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.