| Title | Impact cratering on Earth |
| Download | Download (whole publication) |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Grieve, R A F |
| Source | A synthesis of geological hazards in Canada; by Brooks, G R (ed.); Geological Survey of Canada, Bulletin 548, 2001 p. 207-224, https://doi.org/10.4095/212219
 Open Access |
| Image |  |
| Year | 2001 |
| Publisher | Natural Resources Canada |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| Related | This publication is contained in A synthesis of geological
hazards in Canada |
| File format | pdf |
| Province | Canada |
| NTS | 1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65;
66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560 |
| Lat/Long WENS | -141.0000 -50.0000 90.0000 41.7500 |
| Subjects | extraterrestrial geology; structural geology; meteorite craters; craters; metamorphism, shock; frequency distributions; extinctions, biotic; structural analyses; structural features; structural basins;
health hazards; Distribution |
| Illustrations | photographs; aerial photographs; graphs; sketch maps |
| Released | 2001 04 01 |
| Abstract | Approximately 160 known terrestrial impact structures are distributed worldwide, with concentrations in geologically stable areas. The basic types are simple' craters, up to 4 km in diameter, with
uplifted and overturned rimrocks surrounding a bowl-shaped depression, and complex' structures, generally over 3 km in diameter, with a central uplifted peak and/or ring, an annular trough, and a slumped rim. Morphology is used only to identify
possible impact structures. The impact origin of smaller craters can often be determined by the presence of fragments of the impactor. At large craters, however, the impact commonly melts or completely vapourizes the impactor and verification is
based on shock metamorphism. The formation of impact craters as small as 20 km reduces sunlight and disrupts temperature in a manner similar to a nuclear winter. A large impact event at the Cretaceous Tertiary (K T) boundary is the most likely
cause of impactor mass extinctions that occurred at that time. |
| GEOSCAN ID | 212219 |
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