Germany's Ries and Steinheim craters were formed at the same time by a binary asteroid impact.

The Nördlinger Ries and Steinheim Basin in southern Germany are only about 40 kilometres apart. Both are Miocene impact craters, and for decades they were treated as a classic terrestrial crater pair formed by a binary asteroid: two objects arriving together and striking almost simultaneously.

That interpretation had already begun to weaken before 2022. Fossils and crater-lake sediments suggested that the two structures might not be exactly the same age.

A 2022 study added a particularly direct stratigraphic test. At several sites around the craters, researchers identified two separate layers of sediment deformed by strong seismic shaking. Between them lay roughly 10 to 15 metres of undisturbed sediment and an entire European land-mammal biozone.

The lower disturbed layer matched the time of the Ries impact, while the upper layer matched Steinheim. The evidence placed the events roughly half a million to one million years apart, with Steinheim younger.

The craters remain a striking geographic pair, but they are no longer a good example of one binary asteroid producing two simultaneous impacts.