Formation of Fossils

Since the bottom of the Messel Lake was free of oxygen or currents that could move or fragment the sunken animals and plants, fossils were particularly well preserved in this environment. This is due to the fact that dead organisms can only be preserved over time if they are rapidly and completely covered by sediments. In the course of many millennia, the deposits of clay and single-celled green algae led to the formation of so-called oil shale at the lake bottom. The innumerable instructive fossil discoveries from Messel were all contained in this layer. Thus, a piece of oil shale with a thickness of a mere ten centimeters can reveal a thousand years of geological history.