Geograph - photograph every grid square

For a view of the whole stone in its wider context, see NS3678 : Traces of ancient mud cracks.

The raised ridges are more widely spaced towards the right (the northern end of the boulder), where the enclosed spaces are up to 30cm across, as compared with only 10cm or so at the other end.

I have not elsewhere encountered any report or discussion of these particular stones or their surface patterns, but if this sandstone slab was originally the other way up, it has functioned like a cast by preserving the form of the ancient mud cracks: the cracked surface of the dried mud became covered with sand, which filled the cracks; the sand eventually formed this rock. Another possibility is that this surface is the right way up, and that the original mud cracks became filled with a material that was more resistant to erosion, and which therefore now stands above the surrounding surface. I leave it to geologists to decide which of these two scenarios is correct.

The boulder is located in NS3678 : Carman Quarry. At the time of submission, some smaller examples could be seen elsewhere in the quarry: NS3679 : Traces of ancient mud cracks.