Nördlingen is a small town in Bavaria with a population of 19,000. Towns in Southern Germany are very picteresque with their red roofs and timber-framed (fachwerk) houses, but Nördlingen with its history of more than 1,000 years is a real gem among them.
One of the most noteworthy aspect is the city wall which is complete and accessible to tourists. One can climb up to the wall from one of many guard towers and walk around the whole town which I did when I visited Nördlingen in the late summer of 2011. Such a journey takes a little longer than an hour. During that walk you can take a look at the Nördlingen church in the middle of the town from every direction.
St. George’s church is a really prominent structure because its tower, called Daniel, is 90 meters high. It was built in the 13th century. What is the most fascinating aspect about this church is the material that was used to build it. It is an impact breccia called suevite.
This is the very reason why I visited this town. No, I didn’t know that there is a church built of suevite but I did know that there is a famous impact structure in Southern Germany called the Nördlinger-Ries or just the Ries Crater.
The Nördlinger-Ries is a 14 million years old complex meteorite crater. Its diameter is 24 kilometers and it was created by an impactor 1500 meters in size that slammed into the Earth with an estimated velocity of 20 km/s. The explosion released an amount of energy thought to be equal to 1.8 million Hiroshima bombs.
What is left of the impact structure now is a circular depression about 150 meters deep and 24 kilometers wide. Nördlingen is just in the middle of that structure. The depression was originally thought to be volcanic in origin until one of the founding fathers of impact geology Eugene Shoemaker visited Nördlingen and noticed that the church in the middle of the town in not only notable because of its old age but also because it is built of a very unusual and rare rock type which is always associated with large impact events. Shoemaker published his finds in 1961.
St. George's church in Nördlingen on a postcard from 1919. Image from Wikipedia.
Nördlingen is surrounded by a city wall. The St. George's church is in the middle of the town.
There is a nice geological museum in Nördlingen which is worth a visit. Among other interesting things is a piece of Moon rock. This rock is a gift from the Apollo-11 crew. Neil Armstrong and Buzz Aldrin had various training sessions in a nearby quarry prior to their mission to the moon. They trained skills to handle special tools for picking up samples of moon rock.
As if it isn’t already exciting enough, there is one more interesting aspect about the rocks that are so widely used to build houses in Nördlingen. The rocks that were hit by the meteorite contained graphite (graphite-bearing gneiss) which was turned into diamonds by the immense pressure (60 GPa) exerted by the impact explosion. These diamonds are microscopic (up to 0.3 mm) and have therefore no value as gemstones. However, there are trillions of them. Their estimated total mass is more than 70,000 tons (concentration in rocks reaches 0.7 ppm which is 0.7 grams per one ton of rocks). Hence, the houses in Nördlingen are built from diamonds and impact glass and breccia. I wonder whether people anywhere else in the world have such a noble taste for building materials.
This story is my contribution to the Accretionary Wedge #42.
Suevite from Aumühle quarry which is also located inside the crater. Blue is glassy impact melt. The whole rock is a special type of breccia created by a powerful impact event. The width of the rock is approximately 10 cm.
Another piece of suevite from Aumühle quarry. Suevite from Ries is the original suevite. The place where this rock type was first described. The width of the rock is approximately 10 cm.
Suevite is still mined in Aumühle quarry inside the crater.
One of the guard towers (made of suevite) and city wall.
City wall of Nördlingen offers splendid views to the town from every direction.
Typical houses of Nördlingen. Can you see suevite?
Lovely and a bit out of shape fachwerk-house.
The doors of the church and suevite walls surrounding it. Image: Andreas Praefcke/Wikimedia Commons.
Definitely the most unusual building stone I have seen. Thanks for your post.
Great explanation. I would like to add, that very likely there have been two meteorites. The larger one created the ‘Nördlinger Ries’ the smaller one the “Steinheimer Meteor Crater” only 25km SW. It is believed that the smaller Steinheimer meteorite did orbit around the larger Nördlinger meteorite. There is also a nice little museum in Steinheim. So within 30 km you can get two impact craters and two impact crater museums. If you add 10 more kilometers, you are at a Jurassic coral reef (with museum) and 20 more kilometers you are at Holzmaden, with the world famous Jurassic fossil finds.
Link about the impact crater: http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1443.pdf
Link to WoGE221 : http://woge-felix.blogspot.com/2010/11/i-found-peter-luffis-woge220-within-2.html#comment-form
Wonderful explanation and examples, plus superb photos. Looks like a fascinating place to visit. Thanks for sharing this.
Felix, thanks for the info. I visited Steinheim crater also and have one picture of it taken from the crater rim. I will probably use it later to illustrate some of my future posts. I didn’t stop there for longer though. There are so much interesting geology in Germany. I am sure I will go back some day for a longer visit. Harz mountains which I have briefly visited deserve much more attention and the Eifel volcanic field is very interesting among many other things.
Siim,
thank you for sharing this. I live some kms west of Nördlingen and would have loved to meet you then.
Just to clarify why there is a moon rock at the Nördlingen Geological Museum, I’d like to let you know that this was a gift from the Apollo-11-crew. Neil Armstrong and Buzz Aldrin had various training sessions in a nearby quarry prior to their mission to the moon. They trained skills to handle special tools for picking up samples of moon rock.
Frank, thanks for explaining this. I’ll add it to the article.