Keywords: OrdHdgd03.jpg Cross-section of an Upper Ordovician hardground from Ohio The light-colored vertical elements are Trypanites borings filled with dolomite Photograph taken by Mark A Wilson Department of Geology The College of Wooster http //www3 wooster edu/geology/MWilson html 2007-12-27 Wilson44691 wikipedia en Wilson44691 original upload log page en wikipedia OrdHdgd03 jpg 2007-12-27 15 34 Wilson44691 1000×750×8 287582 bytes <nowiki>Photograph taken by Mark A Wilson Department of Geology The College of Wooster http //www wooster edu/geology/MWilson html</nowiki> Trace fossils Limestone Bioerosion Cincinnatian Hardground |