P number: | P002395 |
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Old photograph number: | C02756 |
Caption: | Columnar jointing in basalt lava, Clamshell Cave, Staffa, Argyllshire. |
Description: | Columnar jointing in basalt lava, Clamshell Cave, Staffa, Argyllshire. Two sets of columnar joints intersect and become parallel in a Tertiary basalt lava flow. The beach in foreground is littered with large basalt blocks broken from the columns. Columnar jointing is a characteristic feature of many minor intrusions. It is especially obvious in sills where the columns are commonly vertical. They originate by the development of a regular series of contraction joints perpendicular to the cooling surface as the rock cools from molten magma to the solid state. The columns are commonly hexagonal in pattern when viewed end-on. |
Date taken: | Thu Jan 01 00:00:00 GMT 1920 |
Photographer: | Manson, W. |
Copyright statement: | Crown |
Acknowledgment: | This image was digitized with grant-in-aid from SCRAN the Scottish Cultural Resources Access Network |
X longitude/easting: | 132500 |
Y latitude/northing: | 735500 |
Coordinate reference system, ESPG code: | 27700 (OSGB 1936 / British National Grid) |
Orientation: | Landscape |
Size: | 254.32 KB; 1000 x 756 pixels; 85 x 64 mm (print at 300 DPI); 265 x 200 mm (screen at 96 DPI); |
Average Rating: | Not yet rated |
Categories: | Best of BGS Images/ Images from the archives, Geoscience subjects/ Structural features/ Jointing, in igneous rocks, Geoscience subjects/ Igneous features/ Lava flows |
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