A group of ten people from the institute went on a geological excursion to the Edersee range on August 30/31. It was led by two experts, Reinhold Wittig, a Göttingen based geologist, and Heiner Heggemann from the Geological Survey of Hessen (Hessisches Landesamt für Umwelt und Geologie). It was interesting to find many relations between the dynamics of complex fluids (on which the participants are conducting their research) and the processes leading to the observed geological fromations.
The Korbach cleft
The first highlight was the visit to the Geopark Korbach Cleft, into which a large number of bones of the mammal-like reptile Procynosuchus (among others) have been washed 300 million years ago (Fig. 1). From this period (Zechstein), many tracks have been found, but only few skeletons. Although there was no complete skeleton found in then cleft, the abundance of bones from that period makes it an important outcrop.
Copper mines
Nest the group visited a quarry close to Korbach, where the stratified Zechstein sediments as well as the first Rotliegend deposits are outcropping in a breathtaking sight (Fig. 2). On some of the strata, one finds copper ores (azurite and cyanite) which were mined for many years, up to 1780 (Martin Luther's father worked there, by the way). The working conditions of those time in the mines are well presented in a Museum in Rotenburg/Fulda, which was the final stop of the group. Small corridors, 50 cm or so in height, with no fresh air and just small oil lamps characterized the life of these hard working people.
Washing gold
In a little river close to the Eisenberg, the group engaged in washing gold (fig. 3), which is transported from the dykes of the Eisenberg into the sediments of nearby creeks. Emotions rose high when the cry 'gold,gold!' was heard for the first time. Fig. 4 shows a few of these 'nuggets', the size of which suggests that there is no economic incentive for such endeavour; it's just great fun -- and a good training for geological imagination.
Underwater avalanches
A substantial part of the rocks in the Erdersee range are turbidites. These have been formed on ocean floors close to the coastlines, where steep slopes enabled the formation of turbidity currents. These are avalanche phenomena driven by the density difference between pure water and sediment suspensions, which may form at the sea floor by a small perturbation (e.g., the movement of a fish or crab). The heavier suspension moves down the slope and may stir up more sediment, which finally may lead to a runaway instability and massive movement of sediment. One such event can result in the coverage of sqare kilometers of sea floor with a tens of centimeters thick layer of new sediment. This can be identified from its graded stratification: the larger particles come to lie below, the small ones go on top.
At the end of the day, the team returned to Göttingen, having seen how many of the things they are doing research on nave direct implicatios on geological phenomena which can be seen in the countryside.
