Nördlinger Ries
Key facts
- Country
- Germany
- Diameter
- 24 km
- Age
- about 14.8 million years
- Location
- 48.88° N, 10.60° E
A flat, fertile basin about 24 km across, ringed by low wooded hills, with the medieval walled town of Nördlingen inside it. Quarries show suevite, a grey impact rock full of glass and broken fragments.
The Ries is a crater people live in. Its floor is a broad, flat plain of farmland and villages in Bavaria, southern Germany, and at its heart lies Nördlingen, one of the best-preserved medieval walled towns in Europe. Stand on the tower of Nördlingen's great church and you can see the low hills of the crater rim curving all around the horizon.
The impact. About 14.8 million years ago, in the Miocene epoch, an asteroid perhaps 1 to 1.5 km across struck the landscape of what is now southern Germany. It blasted out a crater about 24 km wide, flinging rock across the surrounding countryside. A smaller crater, Steinheim, about 40 km to the west, is thought to have formed at the same time, and many geologists think the two were made by a pair of objects travelling together.
Proof in the stone. For a long time the Ries was thought to be volcanic. Its strangest rock, a grey, frothy-looking breccia full of glass and broken fragments, looked a little like volcanic tuff. Geologists named it suevite, from Suevia, the Latin name for Swabia. In 1960 the American geologists Eugene Shoemaker and Edward Chao examined suevite and found coesite, a high-pressure form of silica that forms during impacts but not in normal volcanic eruptions. They had recently found coesite at Meteor Crater in Arizona, and the Ries discovery helped establish how impact craters could be recognised anywhere in the world.
Built from a crater. Nördlingen's people had been building with suevite for centuries without knowing what it was. The town's great St George's Church, with its tall tower known locally as "Daniel", is built largely of suevite. If you look closely at its walls, you can see the dark glassy fragments, formed by the impact, set in grey stone.
Glass that flew to Czechia. The impact also threw out molten droplets that cooled into green glass and landed hundreds of kilometres to the east, in what is now the Czech Republic. These glassy pieces are called moldavites, a type of tektite, and they are prized by collectors and jewellers. Chemical analysis has matched them to the rocks of the Ries.
Training for the Moon. In 1970 the crew of Apollo 14 came to the Ries to study impact rocks before their mission to the Moon. The crater remains one of the most important natural laboratories for impact science.
Visiting. The Ries is now part of a UNESCO Global Geopark. The Rieskrater Museum in Nördlingen explains the impact and displays suevite, moldavites and a piece of Moon rock. Signposted geological trails lead to quarries and viewpoints around the rim. Collecting is restricted at many sites, so check local rules before taking any samples.
Did you know?
Nördlingen's St George's Church is built largely of suevite, a rock formed by the impact.
Green moldavite glass found in the Czech Republic was thrown there by the Ries impact.
Apollo 14 astronauts trained in the Ries crater in 1970.