Unique Fossil Sand Stromatolites from Krukowski Quarry

Coming from the Krukowski Quarry, Mount Simon Wonewoc Sandstone, these unique fossil stromatolites were was on a tidal beach more than 500 million years ago, in what is now Central Wisconsin. This quarry has been producing some intriguing trace or ichnofossils, including huge madusae jellyfish tentacled jellyfish, Diplichnites, Protichnites, and the sand stromatolite you see here, among others.

Sand stromatolite is conjectured to be a nucleation nodule of a small colony of cyanobacteria. Depending on environment conditions, this colony could grow large in the familiar large domes, or would otherwise perish.

Sand stromatolites are uncommon in the Krukowski quarry, and no large stromatolitic structures are found in the vicinity of the formation. Perhaps these small bacterial colonies served as a food source for the early animals that ventured ashore on this ancient Cambrian beach, leaving their footprints in the sand.

Also see: Cambrian Shadows

York, A., Hagadorn, J. W., and Bernstein, J. (2005) Upper Cambrian sand stromatolites of central Wisconsin: Geological Society of America Abstracts with Programs, in press.