In reply to Matthew Newhouse:
Rocky rambles in Snowdonia is a decent book as a start point, but the routes are scrambles at most, not climbs.
Straining my brain a little (it was 20 plus years ago) Carlo Forte I'm sure has some geology or similar background from chats we had on an MIA assessment course. Also Mike Raine has published a nature book. If they can't help I'm sure they can point you in the right direction. Just google up their contact details.