Nördlinger Ries, Rampart crater in Bavaria, Germany

Nördlinger Ries is an impact crater in northern Bavaria whose flat inner basin spans roughly 24 kilometers across and sits about 150 meters lower than the encircling rim. The crater edge remains visible today as gentle slopes and ridges that separate the sunken floor from the higher surrounding countryside.

The impact took place 14.8 million years ago during the Middle Miocene when an asteroid struck the surface and instantly transformed the surrounding bedrock. Researchers only confirmed the true origin in 1960 after discovering coesite minerals that ruled out earlier volcanic theories.

The name Ries comes from Raetia, the Roman province entered here from the west. The crater's identity was settled in 1960 when Eugene Shoemaker and Edward C. T. Chao found coesite in suevite from the Otting quarry; Shoemaker had already been encouraged by St. George's Church in Nördlingen, built of local suevite.

The crater rim is only legible from the air; on the ground it appears as a wooded hill chain on the horizon, so the flat basin floor gives the clearest orientation. The Wörnitz crosses the basin from north to south in many meanders, and the Eger joins it at the southern edge. Nördlingen lies about 6 km south-west of the centre.

The collision turned graphite in the bedrock into microscopic diamonds that remain embedded in historic buildings around the area. Estimates suggest around 72,000 tonnes of these tiny crystals formed at the time and now lie scattered in walls and foundations.