No, I'm just thinner than you RM, so didn't need to break them

Or maybe you got a bit further.
Looked to me like a bedding plane draining surface water, certainly no way on without mining it.
Would be interested to have a look at the survey.
Oh, Andy F - hrock is in foreign parts, namely Mendip
Or maybe Jordan. Easy to confuse the 2, except he appears to have found some cave in Jordan!