File:USGS Decorah crater.jpg
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This is a file from the Wikimedia Commons. The description on its description page there is shown below.
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Summary
| Description |
English: Recent airborne geophysical surveys near Decorah, Iowa are providing an unprecedented look at a 470- million-year-old meteorite crater concealed beneath bedrock and sediments.
The recent geophysical surveys include an airborne electromagnetic system, which is sensitive to how well rocks conduct electricity, and airborne gravity gradiometry, which measures subtle changes in rock density. The surveys both confirm the earlier work and provide a new view of the Decorah Impact Structure. Models of the electromagnetic data show a crater filled with electrically conductive shale and the underlying breccia, which is rock composed of broken fragments of rock cemented together by a fine-grained matrix. |
| Date | 27 February 2013, 23:03:42 |
| Source |
USGS resistivity map of the Decorah crater, url=http://www.usgs.gov/newsroom/article.asp?ID=3521. Archived 2013-03-09 at the Wayback Machine. Additional archives: 2013-03-09. |
| Author | USGS |
| Object location |  | View this and other nearby images on: OpenStreetMap |  |
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Licensing
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This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey, an agency of the United States Department of the Interior. For more information, see the official USGS copyright policy.
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Original upload log
The original description page was here. All following user names refer to en.wikipedia.
- 2013-03-07 17:11 Vkil 2404×2404× (2057822 bytes) Uploading a public-domain item using [[Wikipedia:File_Upload_Wizard|File Upload Wizard]]
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| Date/Time | Dimensions | User | Comment | |
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| current | 07:07, 28 September 2015 | 2,404 × 2,404 (1.96 MB) | OgreBot | (BOT): Uploading old version of file from en.wikipedia; originally uploaded on 2013-03-07 17:11:25 by Vkil |
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