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A circular depression deep in the Democratic Republic of the Congo (DRC) has been confirmed as the first known impact crater in central Africa, a new study says. The find brings the number of known meteor craters on Earth to 182.
The so-called Luizi structure was first described in a German geological report from 1919. But without further fieldwork, it was impossible to say for sure that the 10.5-mile-wide (17-kilometer-wide) feature had been made by a meteor impact.
On other planets, such as Mercury and Mars, it's easier to identify impact craters based only on their shapes, since these worlds no longer have geologic forces making major changes to their surfaces.
(Related: "Martian 'Lake Michigan' Filled Crater, Minerals Hint.")
But on Earth, many older craters have likely been erased by tectonic activity or erosion, while others are so covered with dense vegetation or sediments, like Luizi, that they're almost impossible to spot without satellites.
What's more, the crater-like structures we do see may have been made by volcanoes, collapsed underground chambers, and other forces that have nothing to do with impacts, said study leader Ludovic Ferrière, curator of the rock collection at the Natural History Museum of Vienna in Austria.
Read more: http://news.nationalgeographic.com/...ere-science/?source=link_tw20110308news-congo
