From 1885 to 1971 the oil shale of the middle Messel-Formation, preserved from erosion in a tectonic graben structure, was excavated by open-cast mining. The movements of the artificial slopes have place since 1934 and constitute a potential risk for the railway line, located at the northern brink of the pit, for the new observation platform and for the research scientists. The analysis of measurements proves four active large slides, locally restricted by the tectonic graben faults. Corresponding to different starting positions rotation slides as well as combined rotation- and translation slides appear. The results verify, that a large part of the artificial slopes is situated in a state of fragile balance. The temporary movements correlate with episodic periods of increasing amount of precipitation and confirm the connection between the appearance of movements and the changing quantity of precipitation. At the transition from the graben faults to the nearly impermeable oil shale as well as in the slip planes, occurs, with increasing amount of precipitation or rather ground water, an increasing seepage force, which is, besides the negative influence of water on the shear band material, responsible for the reactivation of slope movements.
The messel pit is world famous for its outstanding hand down of fauna and flora of the early middleeocene. Due to the inestimable value for natural sciences Messel became a member of the UNESCO world heritage list in 1995. From 1885 to 1971 the oil shale of the middle Messel-Formation, preserved from erosion in a tectonic graben structure, was excavated by open-cast mining. After termination of the industrial oil shale-mining, the building of a waste disposal site in the existing hollow space was intended. In 1990 these plans were renounced.
