The crack of doom on the Rhosyfelin pseudo-proto-orthostat

I have had another look at that crack of doom which runs across the top of the famous stone at Rhosyfelin.  It isn't, after all, related to the two dipping fractures which are visible on the south face of the block, but when one looks carefully at the north face one sees that the fracture runs deep into the heart of the block, with a depth of 27 cms.  That's almost half the depth of the block.  It seems to terminate at another foliation plane which we can see as a little projecting ledge.  Yet again this is evidence that the fractures at Rhosyfelin are 'local' and discontinuous.  But this does mean that the strength and stability of this slab is seriously compromised, and I am more convinced than ever that it could never have been moved anywhere without breaking in half.