4-1032: The Earth Impact Database is a database of confirmed impact structures or craters on Earth . It was initiated in 1955 by the Dominion Observatory , Ottawa, under the direction of Carlyle S. Beals . Since 2001, it has been maintained as a not-for-profit source of information at the Planetary and Space Science Centre at the University of New Brunswick , Canada. As of April 2019, the database lists 190 confirmed impact sites. Other lists are wider in scope by including more than just confirmed sites, such as probable, possible, suspected and rejected or discredited impact sites on their lists. These are used for screening and tracking study of possible impact sites. Sites will appear first in these lists while under study and may be incorporated into UNB's Earth Impact Database after confirmation and collection of enough information about
8-417: A planetary surface , whatever the stage of erosion of the structure. In contrast, an impact crater is the surface expression of an impact structure. In many cases, on Earth, the impact crater has been destroyed by erosion, leaving only the deformed rock or sediment of the impact structure behind. This is the fate of almost all old impact craters on Earth , unlike the ancient pristine craters preserved on
12-684: The Moon and other geologically inactive rocky bodies with old surfaces in the Solar System . Impact structure is synonymous with the less commonly used term astrobleme meaning "star wound". In an impact structure, the typical visible and topographic expressions of an impact crater are no longer obvious. Any meteorite fragments that may once have been present would be long since eroded away. Possible impact structures may be initially recognized by their anomalous geological character or geophysical expression. These may still be confirmed as impact structures by
16-674: The site to satisfy the database's strict entry criteria. A previous list was maintained by the Impact Field Studies Group at the University of Tennessee, Knoxville. The Catalogue of the Earth's Impact structures is maintained at the Siberian Center for Global Catastrophes. Impact structure An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on
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