Mark Wilson August 13th, 2010
FRANKFURT, GERMANY–Last year at this time I had the privilege of visiting the Middle Cambrian Burgess Shale on an expedition led by my friend Matthew James of Sonoma State University in California. It was an extraordinary opportunity to visit one of the most important fossil sites in history. Today our IBA field trip had a tour of another UN World Heritage fossil locality: the Messel Pit near Darmstadt, Germany. These Eocene oil shales were formed under very unusual conditions. They are maar deposits formed in a volcanic crater. Catastrophic releases of poisonous gases, the hypothesis goes, occasionally killed the surrounding fauna, causing many to tumble into the anoxic lake to be preserved in amazing detail. This is the home of Ida (Darwinius masillae), the controversial primate fossil now in Oslo (which I also saw last summer).
Our field party was taken down into the center of the maar to an excavation site run by the Senckenberg Museum in Frankfurt. There we watched a team of paleontologists excavate blocks of the shale and examine them for fossils.
Paleontologists extracting large blocks of Messel oil shale to examine for fossils.
Close-up of the Messel Shale. It contains about 40% water in outcrop, and so dries quickly in the sun. Fossils must be kept wet until preserved by various chemicals.
One of the paleontologists splitting Messel Shale with a large knife. The waste pile of examined pieces is behind her. Note the spray bottle of water beside her chair. The fossils must be kept from drying out until they are preserved.
Bits of an Eocene bird found in the Messel Shale while we were visiting.
An artesian well in the center of the Messel structure made when geologists drilled over 400 meters into the shales below. Yes, the tradition is to drink a glass of the water! (And I did.)
An outcrop of the Messel Oil Shale near the eastern side of the pit.
With this memorable paleontological experience our International Bryozoology Association field trip ended. I am grateful to Priska Schäfer of Kiel University for the fantastic (and complicated) organization and leadership. My teaching and research has been greatly enhanced, and I made wonderful new friends as well.
Mark Wilson August 13th, 2010
OPPENHEIM, GERMANY–This jewel of a town, with its large cathedral, half-timbered buildings and narrow streets, share surprising geological connections with Vicksburg, Mississippi — a city visited by Wooster geologists earlier this summer. Both are river towns which profited in good times as trade centers, and both are underlain by Pleistocene loess sediments. Loess is wind-deposited silt and clay that can be easily excavated yet retain vertical walls because of the angular nature of its grains. Residents of both cities dug caverns into their loess deposits to store goods and to escape the dogs of war above them.
Model of a family hiding in a loess cavern underneath Oppenheim, Germany.
Oppenheim is almost completely undermined by up to 200 km of connected tunnels and cellars known collectively as the Kellarlabyrinth. The digging began sometime in the Middle Ages as a way to safely store and transport goods between buildings in the prosperous town. When the religious wars of the 17th century began, Oppenheim was almost continually besieged and occupied by one side or the other. The labyrinth below became a good place to hide from marauding soldiers. The system continually grew as the Oppenheimers dug laterally through the thick bed of loess below their town. The tunnels are still in partial use today after renovation and structural enhancement. In 1945 the American Army successfully crossed the Rhine near Oppenheim. As one of General George Patton’s tanks moved through the streets of Oppenheim, it crashed through the street into a tunnel below. Heavy vehicles have been rerouted around Oppenheim ever since!
You can't have an extensive Medieval cavern system in Continental Europe without some part of it turned into an ossuary. There are the remains of at least 20,000 people in the Oppenheim bone caverns.