The town of Nordlingen in the Donau-Ries district of western Bavaria, Germany, is unlike any other town in the district. In fact, it's unlike any other town on the whole planet. This pretty medieval town, with a population of 20,000, is situated entirely inside a massive meteorite crater 25 km across. This crater called the Nördlinger Ries, was formed some 14.5 million years ago when a meteor about a mile across slammed into Earth. It was only in the 1960s that evidence emerged confirming the town’s extraordinary origin.
The city of Nördlingen. Credit: Wikimedia Commons
For years, it was believed that the shallow depression in the middle of which the town is situated was a volcanic crater. Then in 1960 two American scientists, Eugene Shoemaker (of comet Comet Shoemaker-Levy 9 fame) and Edward Chao, proved that the depression was in fact, caused by meteorite impact. While visiting a church in the town of Nordlingen, Shoemaker reportedly scratched its walls to see what it was made of and was delighted to discover shocked quartz, a type of rock that can only be formed by the shock pressures normally associated with meteorite impact. Subsequent exploration of the strange rock formations of the Ries conclusively established that the crater was caused by a meteor impact.
The Ries asteroid hit what is today the Franconian-Swabian Alb—a mountain range that stretches 220 km from southwest to northeast across Swabia—with a speed of at least 20 km/s. The impact released energy equivalent to 120,000 megatons of TNT and shook the earth with an earthquake of Richter magnitude 8.0. A shock wave swept across the Alb like a hurricane, and the landscape caught fire up to a hundred kilometers away. The explosion gouged the earth creating a crater 500 meters deep and 25 kilometers across. Below the crater, a shock wave speeded through the rock, and the bedrock was shattered kilometers deep. Rock material was ejected from the crater, and a blanket of debris—now called Bunte Breccia— covered the surrounding landscape. A mixture of vaporized and molten rock and ash rose in an explosion cloud and then fell back to the earth’s surface. The solidified mixture formed the impact rock suevite embedded with millions of tiny diamonds. It is this rock the town’s church is made of.
Saint George's church, Nördlingen. Credit: Wikimedia Commons
The catastrophic event of impact and cratering probably lasted about ten minutes, after which all life within a radius of 100 kilometers was extinguished. However, life soon returned to the region: a lake formed in the crater and a diverse flora and fauna settled there. The crater lake was dried up after about two million years and the crater was eventually filled up with sandy-clay sediments.
There is another impact crater the Steinheim crater, about 3.8 km in diameter, located about 42 kilometers west-southwest from the centre of Ries. These two craters were originally believed to have formed nearly simultaneously by the impact of a binary asteroid, but a study published in 2020 suggests that Steinheim could actually be about 500,000 years younger than Nördlinger Ries.
The city of Nördlingen was established in the late 9th century. Under the rule of the Bishops of Regensburg, Nördlingen grew into an important market town. In 1215, Nördlingen was granted city rights by Emperor Frederick II and became imperial city of the Holy Roman Empire. In that year, the first city wall was built, the footprint of which is still visible today. The present-day circular wall was built in 1327, and in 1427 construction of St. George's Church began with rocks quarried from the crater’s outer rim.
Credit: Wikimedia Commons
Despite being a small town, Nördlingen went through a lot of history. It was the site of a well documented witch trials during the late 16th century when 34 women and one man were burned at the stake for the crime of witchcraft. Nördlingen is also the place where in 1604 a shortened and simplified version of William Shakespeare's Romeo and Juliet was performed, and that was one of the first performances of any Shakespearean play outside England.
Nördlingen served as the site of two historic battles, and marked a turning point in the Thirty Years' War. In the first Battle of Nördlingen in 1634, the Swedish Protestant forces sieged the city and the city lost more than half of its population due to hunger and illness. In the early 18th century, during the War of the Spanish Succession, the city was further affected by the impact of nearby battles of Höchstädt. The wars forced trade to shift to the seaports, and as a result, Nördlingen lost its importance as a trading center. In part due to this forced economic standstill, Nördlingen's medieval cityscape remained well preserved.
Part of the crater rim of Nördlinger Ries. Credit: Wikimedia Commons
Nördlinger Ries, Germany. The city of Nördlingen is visible in the far left. Credit: Wikimedia Commons
References:
# “The Nördlinger Ries impact crater”. Digital Geology
# “Nördlingen”. Wikipedia
# Elmar Buchner, Volker Sach, Martin Schmieder. “The Ries-Steinheim crater pair and two major earthquakes – New discoveries challenging the double-impact theory”. Research Square
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