11 January 2012
Splotchy Liesgang banding
Posted by Callan Bentley
At the Three Rondavels overlook in the northern Drakensburg Mountains of South Africa, I saw this chunk of quartzite with a peculiar variety of Liesegang banding (iron oxide staining of the rock by groundwater):
A short distance away, I found another example:
In one key way, I liked this second example better, even though the Liesegang banding wasn’t as well expressed here. The improvement is that it also shows bedding, while the first sample was more massive. You can see that the Liesegang stain fronts overprint the original sedimentary layering within the quartz sandstone:
It’s a palimpsest of geological process!
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.