File:Impact breccia (Cretaceous-Tertiary boundary, 65 Ma; Boltysh Impact Structure, Ukraine) 2.jpg
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| Description |
English: Impact breccia from Cretaceous-Tertiary (K-T) boundary times in Ukraine. (cut & polished surface; ~10 centimeters across at its widest)
Earth experienced a major mass extinction 65 million years ago, at the Cretaceous-Tertiary (“K-T”) boundary. The most famous victims of this event were the dinosaurs, but many other groups of organisms also disappeared. The cause of the K-T extinction has long been a major mystery in geology. Starting in the late 1970s, abundant evidence has accumulated indicating that the dinosaurs & company were wiped out by the effects and aftermath of a gigantic impact event. An approximately 6-mile large object (“bolide”) hit what is now Mexico’s Yucatan Peninsula to form the Chicxulub Crater. Enormous quantities of debris were kicked up into the atmosphere. This material settled out all over Earth to form the K-T boundary clay. It turns out that Earth at end-Cretaceous times experienced a shower of impacting bodies. These include the Kara Impact at 70 Ma, the Boltysh Impact at 65 Ma, the Chicxulub Impact at 65 Ma, and the Shiva Impact at 65 Ma. The rock seen here is an impact breccia from the Boltysh Impact Structure in Ukraine. Impact breccias have a mix of small and large, angular fragments. Clasts include basement rock fragments derived from the Ukrainian Shield - early Mesoproterozoic granites and Paleoproterozoic gneisses. Isotopic dating shows the Boltysh Impact occurred almost simultaneously with the Chicxulub Impact in Mexico. Locality: drill core from 803 meters depth in the Boltysh Impact Structure, central Ukraine Info. at: en.wikipedia.org/wiki/Boltysh_crater |
| Date | |
| Source | https://www.flickr.com/photos/47445767@N05/51469006106/ |
| Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/51469006106. It was reviewed on 12 October 2021 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 18:03, 12 October 2021 | | 4,821 × 2,687 (10.25 MB) | Ser Amantio di Nicolao (talk | contribs) | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/51469006106/ with UploadWizard |
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