Solnhofen Limestone, Geological formation in Bavaria, Germany.

Solnhofen Limestone is a geological formation in Bavaria composed of extremely fine-grained limestone in thin beds separated by shale layers. The deposits formed roughly 150 million years ago in a shallow tropical sea and preserve fossils of various organisms from that ancient environment.

The limestone beds formed during the Jurassic period and were gradually buried and consolidated beneath layers of sediment over millions of years. In the 1800s, systematic quarrying began for lithography and building stone, which led to the discovery of numerous fossils preserved in the rock.

The stone's fine grain made it the standard plate for lithography after Alois Senefelder invented the process in 1796, and it was then known as Lithographenschiefer. In 1828 the Eichstätt glazier Johann Weitenhiller devised the Zwickzange, splitting thin quarry slabs into roof tiles called Biberschwänze, each pierced with a nail hole. Quarrymen still split the layered rock by hand with picks, hammer and chisel.

The quarries lie around Solnhofen, Langenaltheim and west of Eichstätt, reached by road; the open pits are working sites, not a visitor park. The stone is still split by hand with picks, hammers and chisels, so keep to marked tracks and viewing points and never enter the terraces. Ask the local quarries or the tourist offices in Solnhofen and Eichstätt which pits currently admit visitors.

The most famous discovery from these layers is a tiny specimen of Archaeopteryx, a creature showing features of both dinosaurs and birds. This fossil revealed for the first time that the boundary between these two animal groups was not as clear-cut as scientists had previously assumed.