Ries Crater

The Nördlinger Ries is a depression 25 kilometers wide and up to 150 meters deep embedded in the Swabian-Franconian Cuesta Landscape. The bottom today is a plain created by post-impact Ries-Lake sediments and a Pleistocene loess veneer. The structure belongs to the class of “complex” impact craters in which uplifts form an inner ring (Stöffler et al., 2013). Originally the impact of a 1 kilometer asteroid created a primary crater 11 kilometers wide that subsequently was modified by crater floor uplift and marginal collapse (“megablock zone”), which enlarged the crater. As in very few cases on Earth, most of the blanket of ejected masses is preserved. Different rock types are existent, which have been modified or created by the impact. “Bunte breccia” is a polymict breccia with fragments of all stratigraphic, predominantly Mesozoic, \units. Polymict crystalline breccias consist of fragments of the crystalline basement. Most characteristic is the iconic “suevite”, an impact breccia composed of rock and mineral fragments with “glass bombs” of crystalline basement melt. It was deposited from the ejecta plume, a hot, glowing cloud. Because of its similarity with volcanic tuff, the Ries structure formerly was interpreted to have been formed by a kind of volcanic explosion.