The Ries and Steinheim impacts
The crater that proved impacts shape the Earth, and the source of moldavite.
Key facts
- When
- about 14.8 million years ago
- Where
- Bavaria and Baden-Württemberg, Germany
- What hit
- an asteroid about 1 to 1.5 km across for the Ries; a much smaller one for Steinheim
- Era
- Deep time
- Location
- 48.88° N, 10.57° E
Roughly 100,000 megatons of TNT, give or take a factor of a few.
Several million times the Hiroshima bomb; a thousandth or so of Chicxulub.
What happened
The Nördlinger Ries is a round, flat basin about 24 km across in southern Germany, with the medieval town of Nördlingen near its middle. For a long time it was thought to be volcanic. In 1960 the American geologists Eugene Shoemaker and Edward Chao found coesite, a form of quartz made only at very high pressure, in the local building stone, a rock called suevite. That proved the Ries was made by an impact, and it became one of the first craters on Earth confirmed this way.
About 40 km to the south-west lies the smaller Steinheim Basin, 3.8 km across, with a central hill. The two have long been thought to have formed together, perhaps from an asteroid with a small moon, although some researchers have recently questioned whether they are exactly the same age.
Effects
Rock and debris were thrown up to around 200 km away, burying the landscape nearby. Molten surface rock was flung even further, cooling into green glass that fell in what is now the Czech Republic, up to about 450 km away: the gem-like tektites called moldavites. A lake later filled the crater and laid down sediments rich in fossils.
The evidence
Coesite, stishovite and shocked quartz in suevite, shatter cones at Steinheim, the matching age of the moldavites, and drilling and geophysical surveys of the basin.
Did you know?
The tower of St George's Church in Nördlingen is built from suevite, which contains tiny impact diamonds.
Apollo astronauts trained in the Ries in 1970 to learn how to recognise impact rocks on the Moon.
Related pages
How is impact energy measured? See energy explained, or try the impact calculator.