File:Libyan Desert Glass tektite (Oligocene, 28.5 Ma; Libyan Desert, Egypt) 2.jpg
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Summary
[edit]DescriptionLibyan Desert Glass tektite (Oligocene, 28.5 Ma; Libyan Desert, Egypt) 2.jpg |
English: Libyan Desert Glass from the Oligocene of Egypt. (public display, meteorite museum at Odessa Impact Crater, Texas, USA)
Large & small impacts have affected Earth since its formation 4.55 billion years ago. Compared with the intensely pitted and cratered Moon, Earth has relatively few preserved impact craters, because they have been destroyed by water & glacial erosion. Impact events are accompanied by tremendous amounts of heat, resulting in melting of much of the ejected pulverized bedrock at ground zero. The melted material cools quickly, and falls back to Earth in the form of impact splash glasses (a.k.a. tektites). Tektites are principally composed of amorphous silica (SiO2). Broken surfaces show a conchoidal fracture. Tektites from different impact events are given different names. Tektites called Libyan Desert Glasses are known from a large area in western Egypt’s Libyan Desert. These nearly pure silica glasses range in color from pale yellowish to yellowish-green to brownish. Their surfaces have been sculpted by wind-blown sand abrasion. Available age information indicates that these rocks formed during the mid-Oligocene (28.5 million years ago). The responsible impact crater(s) have not been identified with certainty. |
Date | |
Source | https://www.flickr.com/photos/47445767@N05/14609848638/ |
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@N05/14609848638 (archive). It was reviewed on 27 January 2020 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
27 January 2020
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 21:27, 27 January 2020 | 2,080 × 1,555 (1.93 MB) | Ser Amantio di Nicolao (talk | contribs) | User created page with UploadWizard |
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Metadata
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.
Camera manufacturer | NIKON CORPORATION |
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Camera model | NIKON D70s |
Exposure time | 1/60 sec (0.016666666666667) |
F-number | f/5.6 |
Date and time of data generation | 16:13, 27 August 2007 |
Lens focal length | 200 mm |
Orientation | Normal |
Horizontal resolution | 300 dpi |
Vertical resolution | 300 dpi |
Software used | Adobe Photoshop CS2 Macintosh |
File change date and time | 15:40, 31 July 2014 |
Y and C positioning | Co-sited |
Exposure Program | Not defined |
Exif version | 2.21 |
Date and time of digitizing | 16:13, 27 August 2007 |
Meaning of each component |
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Image compression mode | 4 |
APEX exposure bias | 0 |
Maximum land aperture | 5 APEX (f/5.66) |
Metering mode | Pattern |
Light source | Unknown |
Flash | Flash fired, strobe return light detected, auto mode |
DateTime subseconds | 80 |
DateTimeOriginal subseconds | 80 |
DateTimeDigitized subseconds | 80 |
Supported Flashpix version | 1 |
Color space | sRGB |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Scene type | A directly photographed image |
Custom image processing | Normal process |
Exposure mode | Auto exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Focal length in 35 mm film | 300 mm |
Scene capture type | Standard |
Scene control | Low gain up |
Contrast | Normal |
Saturation | Normal |
Sharpness | Normal |
Subject distance range | Unknown |
Supported Flashpix version | 1 |
Image width | 2,080 px |
Image height | 1,555 px |
Date metadata was last modified | 11:40, 31 July 2014 |