File:Coquina (Anastasia Formation, Pleistocene or Holocene; Cayo Costa Island, Florida, USA) (26032505336).jpg
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Summary
[edit]DescriptionCoquina (Anastasia Formation, Pleistocene or Holocene; Cayo Costa Island, Florida, USA) (26032505336).jpg |
Coquina from the Quaternary of Florida, USA. Sedimentary rocks form by the solidification of loose sediments. Loose sediments become hard rocks by the processes of deposition, burial, compaction, dewatering, and cementation. There are three categories of sedimentary rocks: 1) Siliciclastic sedimentary rocks form by the solidification of sediments produced by weathering & erosion of any previously existing rocks. 2) Biogenic sedimentary rocks form by the solidification of sediments that were once-living organisms (plants, animals, micro-organisms). 3) Chemical sedimentary rocks form by the solidification of sediments formed by inorganic chemical reactions. Most sedimentary rocks have a clastic texture, but some are crystalline. Limestone is a common biogenic sedimentary rock composed of the mineral calcite (CaCO3), which bubbles in acid. Many geologically young limestones are composed of aragonite (also CaCO3). Numerous varieties of limestone exist (e.g., fine-grained limestone/micritic limestone/lime mudstone, coquina, chalk, wackestone, packstone, grainstone, rudstone, rubblestone, coralstone, calcarenite, calcisiltite, calcilutite, calcirudite, floatstone, boundstone, framestone, oolitic limestone, oncolitic limestone, etc.). The most distinctive type can be given the generalized name fossiliferous limestone, which is composed of abundant whole & fragmented fossil shells and skeletons, usually mixed with mud. Most limestones represent deposition in ancient warm, shallow ocean environments. The sample shown above is a distinctive variety of fossiliferous limestone called coquina. It is composed of mollusc shells and fragmented shells (typically clam and snail shells - bivalves and gastropods). Coquinas have high porosity - a significant amount of empty space exists between the grains. This results in coquina having a spongy appearance. Coquina had military significance in early American history. Some military forts in Florida were constructed with coquina walls. The coquina essentially absorbed any cannonballs that were shot at the fort. Coquina is a fairly common sedimentary rock in the Quaternary of Florida. Stratigraphy: Anastasia Formation, Pleistocene or Holocene Locality: loose piece on marine beach near the southern end of the western shoreline of Cayo Costa Island, Gulf of Mexico coast of southwestern Florida, USA (vicinity of 26° 36' 51.30" North latitude, 82° 13' 24.39" West longitude) |
Date | |
Source | Coquina (Anastasia Formation, Pleistocene or Holocene; Cayo Costa Island, Florida, USA) |
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@N05/26032505336. It was reviewed on 14 August 2016 by FlickreviewR and was confirmed to be licensed under the terms of the cc-by-2.0. |
14 August 2016
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 17:35, 14 August 2016 | 2,849 × 2,000 (3.39 MB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via Flickr2Commons |
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Metadata
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Camera manufacturer | NIKON CORPORATION |
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Exposure time | 1/800 sec (0.00125) |
F-number | f/11 |
ISO speed rating | 400 |
Date and time of data generation | 09:23, 29 August 2009 |
Lens focal length | 105 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 13.0 (Macintosh) |
File change date and time | 22:19, 26 March 2016 |
Y and C positioning | Co-sited |
Exposure Program | Not defined |
Exif version | 2.21 |
Date and time of digitizing | 09:23, 29 August 2009 |
Meaning of each component |
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Image compression mode | 4 |
APEX shutter speed | 9.643856 |
APEX aperture | 6.918863 |
APEX exposure bias | 0 |
Maximum land aperture | 4.9 APEX (f/5.46) |
Metering mode | Pattern |
Light source | Unknown |
Flash | Flash did not fire, compulsory flash suppression |
DateTime subseconds | 00 |
DateTimeOriginal subseconds | 00 |
DateTimeDigitized subseconds | 00 |
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 | 157 mm |
Scene capture type | Landscape |
Scene control | None |
Contrast | Normal |
Saturation | Normal |
Sharpness | Hard |
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 | 16:19, 26 March 2016 |
Unique ID of original document | 07456389319A9B640EE35A8D0E62D344 |