The pale limestone of this site was laid down in the Eocene period (50 million years ago) under a freshwater lake. It is one of palaeontology’s great "murder mysteries" in that an abundance of mammal and bird fossils are found here in great numbers; most in near perfect condition showing fine detail such as feathers and skin impressions.
The mystery is what killed all of these animals? Current theories include the production of large quanities of noxious gas by underwater decomposition or volcanic origin.