Oblique aerial view of the Ries Impact Structure from the southwest with the outline of the crater rim emphasized by clouds
Photo: Earth Impact Database
Location: Southern Bavaria, Germany
Scale: Diameter of the crater is approximately 24 kilometers

Aerial view of the town Nördlingen
Photo: City of Nördlingen
Location: Town of Nördlingen, along the margin of the structure's "inner ring"
Scale: Diameter of the circular wall around the city is approximately 1 kilometer

Ries Crater is located in southern Germany (48º 53' N, 10º 37' E), north of the Danube river in western Bavaria.

The impact structure is easily accessible along the "Romantische Strasse", the Romantic Road that winds through Bavaria from Frankfurt to Munich.

In the crater interior is Nördlingen, a beautiful midieval town that is completely walled, one of the few left in all of Germany.

There is an excellent museum about the Ries structure in Nördlingen (see image below).

Rieskrater Museum
Photo: E. Pierazzo, Planetary Science Institute
Location: Town of Nördlingen, along the margin of the structure's "inner ring"
Scale: Height of the gray door is 3.5 meters

The ~24 kilometer diameter Ries impact structure in Germany is one of the best-preserved meteorite impact craters on Earth. This unique geological site in Bavaria was formed approximately 14.5 million years ago in a target composed of ~500–800 meter thick flat-lying sedimentary rocks overlying a crystalline basement of granite and gneiss.

For over 100 years, the Ries structure was considered to be a volcanic crater, but as we'll see on our tour, the evidence for an impact origin is overwhelming. The foundations for the reinterpretation of Ries as a meteorite impact crater came from the discovery of coesite and stishovite, high-pressure versions of quartz, by Eugene Shoemaker and Edward Chao in the 1960's.

Although the Ries structure is well preserved, it is not well exposed. This is because the entire structure has been partially filled by sediment, cultivated for farmland, and covered by isolated pockets of forests. This is very different compared to the Haughton impact structure in Canada, which is located in a polar desert environment.

Cross-section of the Ries impact structure
Figure: G. Osinski, Canadian Space Agency, modified from Hüttner and Schmidt-Kaler (1999)