P number: | P007662 |
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Old photograph number: | A13448 |
Caption: | Craig-y-cwm, rear wall. |
Description: | Craig-y-cwm, rear wall. Calcrete beneath fining-upwards cycle of pebbly grit. The Quartz Conglomerate Group (Upper Old Red Sandstone) contains a dull red, trough and festoon cross-bedded pebbly and gritty sandstone, laterally equivalent to coarse quartz pebble conglomerates. The grit is 1.6 m. - 2.3 m. thick at Craig-y-cwm with a basal 0 - 0.2 m. lag with cornstone clasts. Towards the top, thin discontinuous beds of planar cross-laminated medium-grained green sandstone occur. The grit is interpreted as the channel-fill of a braided river with scour and fill; as current activity wanes, slip faces on the bar margins accumulate sandstone. The grit irregularly but sharply overlies a lenticular concretionary cornstone, 0.22 m. - 0.68 m. thick, interpreted as an immature calcrete (pedogenic carbonate). The calcrete rests on a calcareous poorly-bedded green sandstone with decomposed marl clasts on the cross-bedded foresets. |
Date taken: | Sun Jan 01 00:00:00 GMT 1978 |
Photographer: | Pulsford, J.M. |
Copyright statement: | NERC |
Acknowledgment: | This image was digitized with grant-in-aid from JIDI the JISC Image Digitization Initiative |
X longitude/easting: | 328270 |
Y latitude/northing: | 208840 |
Coordinate reference system, ESPG code: | 27700 (OSGB 1936 / British National Grid) |
Orientation: | Landscape |
Size: | 334.47 KB; 1000 x 678 pixels; 85 x 57 mm (print at 300 DPI); 265 x 179 mm (screen at 96 DPI); |
Average Rating: | Not yet rated |
Categories: | Unsorted Images, Geoscience subjects/ Sedimentary features/ False-bedding, cross, current and dune |
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