Geograph - photograph every grid square

This feature can be seen NS3974 : At the foot of Dumbarton Rock; it is located in the grey area (composed of shale) that can be seen at the centre of that photo. The upright structure at the centre of the image is a block formed of cementstone concretions, and measures 50cm from left to right. It is surrounded by calcite veins; similar veins were evident in many of the rocks in the area, some of them 2cm or more in width; page 91 of the book "Wildlife Around Glasgow" (Richard Sutcliffe, 2010) mentions, regarding this location, that "thin veins of calcite cut the rocks".