list of cryptovolcanic structures. The recognition of a projectile signal at Rochechouart and progressively at other impact structures and especially at the K-T boundary a few years later, definitely terminated the era of cryptovolcanism and skepticism toward impact cratering. Age The age of the Rochechouart impact is a matter of debate. The ages (within the error bars) spans from less than 150 million years ago to over 240 million years. Since late 1990s the spreading has reduced and the last four determinations (since 2010) are converging toward an age between 203 and 207 million years during the Rhaetian, two to five million years older than the Triassic-Jurassic boundary. Hypothetical multiple impact event Geophysicist David Rowley, working with John Spray and Simon Kelley, suggested that Rochechouart may have been part of a hypothetical multiple impact event which also formed the Manicouagan impact structure in northern Quebec, Saint Martin crater in Manitoba, Obolon' crater in Ukraine, and Red Wing crater in North Dakota. All of the impact structures had previously been known and studied, but their paleoalignment had never before been demonstrated. Rowley has said that the chance that these impact structures could be aligned like this due to chance are nearly zero. However, more recent work has found that the craters formed many millions of years apart, with the Saint Martin crater dating to 227.8 ± 1.1 Ma. While the Manicouagan impact structure dates to around 214 ± 1 million years ago. Geological setting The Rochechouart impact structure is located on the margin of the French Massif Central. The target rocks exposed both in the center of the structure below the deposit, and radially outward are largely dominated by gneisses (blue and green on the map) and granites (pink on the map). These metamorphic and intrusive rocks were emplaced some 350-300 million years ago during the Variscan orogeny. The latter also referred as to Hercynian orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between the tectonic plates of Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. This caused the rise of Himalaya-like mountain ridges of the Massif Central, among others. The mountains were already eroded and transformed into a peneplain at the time of the impact. The center of the structure is only from the closest sediments. The later were deposited after the impact. Yet the impact has most probably taken place on the margin