German Suevite and a Mysterious Crater

Written by Connor Clinton, Science Communication Student at the University of Sheffield

This specimen of German Suevite stands out in the collection because of its modern looking label. The suevite was presented to the Sedgwick Museum by Dr Peter Friend, a retired member of the Department of Earth Sciences at the University of Cambridge. He received it in 2017 from a member of the Ries Crater Museum during a field trip to the Nӧrdlinger Ries, a 16 mile-wide crater located in Southern Germany. In the 1960s, two American scientists, Eugene Shoemaker and Edward Chao, uncovered the truth behind the crater’s formation.

During the early 20th century, geologists suspected the crater had been formed by volcanic activity due to its shape and the presence of what appeared to be volcanic rocks. It was only in 1960 that its true origin was revealed, when Shoemaker and Chao visited Nӧrdlingen, a small town located in the crater. They were investigating the geological history of the crater, doubtful of its proposed volcanic origins. As the story goes, while standing at St. George’s Church, Shoemaker scratched its walls and was amazed to see shocked quartz, a mineral only formed by extreme instantaneous pressures associated with high-impact events.

Shoemaker and Chao subsequently analysed rock from the church and the surrounding crater. They found suevite containing coesite, a rare form of quartz they had previously identified at Meteor Crater in Arizona. This discovery prompted further studies that provided strong evidence the crater was not volcanic, but the result of an asteroid impact. It is now widely accepted that an asteroid struck the area 15 million years ago, carving out a crater 500 metres deep. The impact threw up a cloud of ash and a mixture of vaporised and molten rock, which then fell back to the ground and solidified into suevite. A sample of this impact rock now resides in Watson's collection.