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Uploaded on:
12/03/2009 10:56:04
Type:
Digital Asset
File Size:
104.06 KB
Dimensions:
1000 x 667 pixels
81 views 4 downloads
P number: P524306
Caption: Photomicrograph of tachylite. Light: PPL, Magnification x 2. Camas na Cairdh, Muck, Invernessshire.
Description: The image is an unusual photomicrograph of a thin section of a tachylite rock which has bright mineralised gas vesicles within a black opaque glassy volcanic matrix. Alteration of the rock is seen as a series of radial fractures emanating from the vesicles. British Geological Survey Petrology Collection sample number S 97037. Light: PPL, Magnification x 2. Light: PPL, Magnification x 2. The volcanic basaltic rock cooled so quickly when it was erupted that there was insufficient time for crystals to grow. Therefore the liquid lava was frozen as a very fine-grained rock with a glassy texture. Bubbles of gas trapped in the lava were preserved as vesicles. Extensive subaerial volcanism marked the start of the Tertiary era in the Hebrides with the extrusion of huge amounts and great thicknesses of plateau lavas over a wide area from Mull, Rum and the Small Isles to Skye and Raasay and also Northern Ireland. Lava effusion appeared to be gentle, flows followed each other building up flat-lying successions. The plateau lavas on Muck have been dated at 63 Ma.
Date taken: 01/01/2003
Photographer: Hyslop, E.K.
Copyright statement: NERC
X longitude/easting: 141400
Y latitude/northing: 780500
Coordinate reference system, ESPG code: 27700 (OSGB 1936 / British National Grid)
Orientation: Landscape
Size: 104.06 KB; 1000 x 667 pixels; 85 x 56 mm (print at 300 DPI); 265 x 176 mm (screen at 96 DPI);
Average Rating: Not yet rated
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