2 February 2012
Posted by Callan Bentley
Rust swirls on shale fragment, new New Route 55, Valley & Ridge province of West Virginia. I’m not sure if I can call this “Liesegang banding,” since it’s just on the joint surface (two-dimensional) rather than permeating the rock in a three-dimensional blob. Anyhow… It’s pretty.
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.
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Wow, I actually have a hard time registering that as a rock when I look at that. It bears a remarkable resemblance to the end-grain of a piece of wood.
I’m intrigued by the apparent truncation/displacement of the bands in the upper left corner of the specimen, on either side of the zig-zagging grey vein(?). Is that for real, or just a trick of the perspective? If it’s real, it’s hard to imagine how a surface stain would be truncated like that. I wonder if perhaps this really is 3-D liesegang banding that may not be visible on a fresh surface when you smash it open, but needs to be “developed” (in the sense of a latent photographic image) by surface weathering?
You sure have the knack for finding the thought-provoking specimens!
Hi Howard– that’s two different levels; two different joints of parallel orientation, each decorated with it’s own unique filigree of iron oxide. The top-most level is, I think, the same joint as the bottom-most.
From Howard: “but needs to be “developed” (in the sense of a latent photographic image) by surface weathering?”
Cool metaphore, Howard.
Cool pic, Cal.