Geopark Ries

The Nördlinger Ries is a large circular depression in western Bavaria, Germany, located north of the Danube in the district of Donau-Ries. The city of Nördlingen is located about 6 kilometers (3.7 mi) southwest of the centre of the depression.

"Ries" is derived from Raetia, since the tribe of Raetians lived in the area in pre-Roman times.

The depression is interpreted as a meteorite impact crater formed about 14.3 million–14.5 million years ago in the Miocene. The crater is most commonly referred to simply as the Ries or Ries crater. The original crater rim had an estimated diameter of 24 kilometers (15 mi). The present floor of the depression is about 100 to 150 m (330 to 490 ft) below the eroded remains of the rim.

It was originally assumed that the Ries was of volcanic origin. In 1960 Eugene Shoemaker and Edward C. T. Chao showed that the depression was caused by meteorite impact. The key evidence was the presence of coesite, which, in unmetamorphosed rocks, can only be formed by the shock pressures associated with meteorite impact. The coesite was found in the locally derived suevite building stone of the Nördlingen town church. The suevite was formed from mesozoic sediments shocked by the bolide impact.

The Ries impact crater as a rampart crater, which is thus far a unique finding on Earth. Rampart craters are almost exclusively found on Mars. Rampart craters exhibit a fluidized ejecta flow after impact of the meteorite, most simply compared to a bullet fired into mud, with the ejecta resembling a 'mudflow'.

Another impact crater, the much smaller (3.8 km diameter) Steinheim crater, is located about 42 km (26 mi) west-southwest from the centre of Ries. The two craters are believed to have formed nearly simultaneously by the impact of a binary asteroid.

...
Wikipedia