|LOWER SURFACE, PARALLEL TO BEDDING, OF SKELTAL LIMESTONE FROM BASE OF LINCOLN MEMBER, RUSSELL COUNTY, SHOWING CONVEX HYPORELIEF BELIEVED TO BE FECAL CASTINGS. (HATTIN, 1975).|
A year ago I stopped at an outcrop of Greenhorn Limestone in Russell County, Kansas, to collect a few inoceramid bivalves. The Greenhorn is part of the Cretaceous rock column deposited in the great Western Interior Seaway. The Greenhorn is quite fossiliferous and all visitors are able to locate a number of invertebrate fossils. As I was turning over slabs of the Greenhorn I stumbled upon a thin bedded piece of limestone that had a number of "strange" raised markings on the underside (below). I did not have a clue as to the origin of these markings and really did not know if they were inorganic or organic in nature. But, as many rockhounds often do, I threw the specimen in my bag and then into the home rock garden. I have often looked at the rock in my garden but could not quite come up with an answer as to "what is was". Last night, in one of those serendipitous moments, I perhaps identified the markings! I was rereading Don Hattin's tome on Greenhorn stratigraphy and there it was, I think. A photo of a similar looking specimen with a caption of "convex hyporeliefs believed to be fecal castings"(below). So, I realize that my mystery rock has a surface of pellets put out by some sort of "fish". Now, every time I see the specimen in the rock garden I smile just a little. Wish all the identifications were that easy.
|FECAL CASTINGS ON SMALL SLAB OF GREENHORN LIMESTONE.|
Hattin, D. E., 1975, Stratigraphy and Depositional Environment of Greenhorn Limestone (Upper Cretaceous) of Kansas: Kansas Geological Survey Bulletin 209.