The Domaine du Meteore winery in the south of France gets its name from a dramatic depression in the land where it grows grape vines. It turns out that the name is more than a marketing ploy. Geologist and cosmochemist Frank Brenker of Goethe University Frankfurt says it has been proven to be true.
Twenty years ago, geologists disagreed about how the 720-foot-wide (220 meters) and 100-foot-deep (30 meters) depression was formed. Some thought it might have been a meteorite impact. But others said no, thanks in part to the lack of a raised rim around the edge of the depression, and everyone went with that. Until now.
“Craters can form in many ways, and meteorite craters are indeed very rare,” Brenker said in a statement from Goethe University on Wednesday. “However, I found the various other interpretations of how this depression could be geologically inconclusive.”
Brenker carefully observed the depression and began looking for signs of a long-ago meteorite impact. A meteorite crater can be difficult to see. Over time, erosion and other geological processes cover the evidence. Brenker’s paper on the French winery crater (PDF link) notes that small impact craters (under 1,000 feet / 300 meters in diameter) are extremely rare and that proving their extraterrestrial origin is challenging.
Analysis has found evidence of cemented together rocks called breccia that can be associated with meteorite impacts. Brenker, geophysicist Andreas Junge and a team of students took a field trip to get a closer look. They measured a weak magnetic field at the site. “This is typical for impact craters because the impact shatters or even melts the rock, which contributes less to the Earth’s magnetic field,” said the university.
The team used a powerful magnet to pull up small spheres of iron oxide, another key ingredient found in other meteorite impact craters. A combination of geological and mineralogical evidence points to space rock as the culprit behind the depression.
Domaine du Meteore took on another origin story. The vineyard proudly proclaims, “These are wines from another dimension.”