File:Cougar Point Welded Ash-Flow Tuff (Miocene, 10.5-12.5 Ma; near Grasmere, Idaho, USA) 1.jpg
![File:Cougar Point Welded Ash-Flow Tuff (Miocene, 10.5-12.5 Ma; near Grasmere, Idaho, USA) 1.jpg](https://upload.wikimedia.org/wikipedia/commons/thumb/0/05/Cougar_Point_Welded_Ash-Flow_Tuff_%28Miocene%2C_10.5-12.5_Ma%3B_near_Grasmere%2C_Idaho%2C_USA%29_1.jpg/780px-Cougar_Point_Welded_Ash-Flow_Tuff_%28Miocene%2C_10.5-12.5_Ma%3B_near_Grasmere%2C_Idaho%2C_USA%29_1.jpg?20221112192401)
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[edit]DescriptionCougar Point Welded Ash-Flow Tuff (Miocene, 10.5-12.5 Ma; near Grasmere, Idaho, USA) 1.jpg |
English: Rhyolitic welded tuff from the Tertiary of Idaho, USA. (public display, Ashfall Fossil Beds State Historical Park, Nebraska, USA)
Volcanic tuff is a clastic-textured, extrusive igneous rock. Such rocks form from explosive volcanic eruptions. Tuff is composed of fine-grained particles - it's basically a solidified volcanic ash deposit. The original ash may have been deposited after falling from the sky (ash fall tuff) or after rushing across the landscape (ash flow tuff). Sometimes, the ash deposit is so hot that it self-lithifies before burial - it becomes a welded tuff. Occasionally, the heat is sufficient to melt the ash particles; with cooling, this results in glass. Seen here is a welded ash flow tuff sample from a Miocene-aged volcanic center in southwestern Idaho called the Bruneau-Jarbidge Caldera. The volcano is part of the Yellowstone Hotspot track in southern Idaho. Volcanoes in this chain have large, explosive eruptions. Lava flows from effusive eruptive activity cover parts of the hotspot track in southern Idaho's Snake River Plain. The Bruneau-Jarbidge Caldera has been identified as the source volcano for a famous fossiliferous ash deposit in northeastern Nebraska - Ashfall Fossil Beds. Numerous skeletons of Miocene vertebrates are preserved in the ash. From exhibit signage: FROM THE CRATER This rock solidified from a cloud of glowing hot ash ejected from a huge volcano in Idaho. Rock name: Cougar Point Welded Ash-Flow Tuff Composition: Rhyolitic - very rich in silica (Equivalent to granite, but much finer grained.) Location: Southwestern Rim of Bruneau-Jarbidge Caldera, 8 miles southwest of Grasmere, Idaho on State Highway 51. Age: 10.5 to 12.5 million years. This deposit was named by Bill Bonnichsen of the Idaho Bureau of Mines. He first identified the Bruneau-Jarbidge Caldera as the source of the Ashfall ash in 1982. Locality: exposure along Route 51, about 8 miles southwest of the town of Grasmere, southwestern Idaho, USA |
Date | |
Source | https://www.flickr.com/photos/47445767@N05/52354835249/ |
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@N05/52354835249. It was reviewed on 12 November 2022 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
12 November 2022
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current | 19:24, 12 November 2022 | ![]() | 2,565 × 1,972 (5.19 MB) | Ser Amantio di Nicolao (talk | contribs) | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/52354835249/ with UploadWizard |
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Camera manufacturer | NIKON CORPORATION |
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Camera model | NIKON D70s |
Exposure time | 1/125 sec (0.008) |
F-number | f/7.1 |
ISO speed rating | 400 |
Date and time of data generation | 13:31, 5 August 2011 |
Lens focal length | 90 mm |
Width | 3,008 px |
Height | 2,000 px |
Bits per component |
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Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 300 dpi |
Vertical resolution | 300 dpi |
Software used | Adobe Photoshop Elements 18.0 (Macintosh) |
File change date and time | 06:04, 13 September 2022 |
Y and C positioning | Co-sited |
Exposure Program | Not defined |
Exif version | 2.21 |
Date and time of digitizing | 13:31, 5 August 2011 |
Meaning of each component |
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Image compression mode | 4 |
APEX shutter speed | 6.965784 |
APEX aperture | 5.655638 |
APEX exposure bias | 0 |
Maximum land aperture | 4.8 APEX (f/5.28) |
Metering mode | Pattern |
Light source | Unknown |
Flash | Flash fired, strobe return light detected, auto mode |
DateTime subseconds | 20 |
DateTimeOriginal subseconds | 20 |
DateTimeDigitized subseconds | 20 |
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 | 135 mm |
Scene capture type | Standard |
Scene control | None |
Contrast | Normal |
Saturation | Normal |
Sharpness | Normal |
Subject distance range | Unknown |
Serial number of camera | 200638ad |
Lens used | 18.0-200.0 mm f/3.5-5.6 |
Date metadata was last modified | 02:04, 13 September 2022 |
Unique ID of original document | 94B4D5062991432DB6E5EA1773F6CCDA |
IIM version | 12,651 |