Trace Fossils in Hanover Formation
October 07, 2021
Photographer: James R. Ebert
Summary Author: James R. Ebert
Unlike body fossils (shells, bones, chitinous material, plant tissue, etc.), which are the actual remains of once living organisms, trace fossils or ichnofossils are marks (burrows, tracks, trails, etc.) made by the activity or behavior of an organism. This photo shows an abundance of burrows of the ichnogenus Planolites in a bed of dark gray to black shale in the Hanover Formation, exposed in Sheridan Bay on Lake Erie, east of the city of Dunkirk, New York. The contrast between the sediment fill of the burrows and the surrounding shale is enhanced because the bed containing the burrows is wet owing to its position at lake level. Note that the trace-makers responsible for Planolites were probably worm-like creatures that tunneled through the mud, ingesting the sediment, digesting the organic matter that it contained, and excreting the undigested sediment as fill in the tunnels behind the organisms. Photo taken on June 28, 2021