Messel Pit

The Messel Pit is a fossil preservation site in Hesse, central Germany, dated to the Eocene epoch. The fossil-bearing rock unit is a geologic formation named the Messel Formation; its geographic range is restricted to the Messel pit. There, the formation unconformably overlies crystalline Variscan basement and its Permian cover (Rotliegend) as well as Eocene volcanic breccias derived from the base... (Wikipedia)