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.
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.