Messel Pit

The Messel Pit is a disused quarry near about 35 km southeast of Frankfurt am Main.

Oil shale was mined here from 1859. The pit first became known for its wealth of fossils around 1900, but scientific excavation only started around the 1970s, when falling oil prices made mining the quarry uneconomical and the mining ceased in 1971. In 1974 the state began preparing the site for garbage disposal what created strong local resistance, that finally stopped the plans for a landfill.

The area around the pit is believed to have been geologically and tectonically active during the Eocene. Periodic subsurface shifts possibly released large concentrations of reactive gases into the lake and adjoining ecosystems. During these releases, animals could be overwhelmed when near the lake. Since the lake was very deep, animals that fell in it drifted downwards into oxygen- and bacteria-poor water, where they were preserved remarkably well, being overlaid by successive layers of mud that petrified later, thus producing an aggregation of fossils of exceptional quantity and variety.

The Messel Pit was declared a UNESCO World Heritage site in 1995. Significant scientific discoveries are still being made and the site has increasingly become a tourist site as well, as next to it now is an excellent museum, where the visitor can see this skeleton of a "eurohippos messelensis", which is 50-40 million years old. It is a very early link in the evolution of the horse. These were small animals, ranging from 30–60 cm at the shoulder. They had no hooves, having instead several small nail-like hooflets.