Eyup Pilgrim,

I guess the copyright thing is probably best left alone if you're not sure :(

Regarding books on cup marks, the works of The Remarkable Stan Beckensall are always worth a look, though they emphasise the more complex carvings, he does pay attention to the humble cup.

A good one to start with would be his 'British Prehistoric Rock Art' (ISBN 0 7524 2514 5)
More emphasis is to be found on simpler motifs in 'Prehistoric Rock Art of County Durham, Swaledale and Wenselydale' co-authored with Tim Laurie. (ISBN 1 897585 45 4)

Whilst out of print, Ronald Morris' 'The Prehistoric Rock Art Of Argyle' (ISBN 0 85642 059 X) can still be found, but the emphasis is again on more complex motifs (and boy! Do they look good!)

Then for another out of print but still findable, there's 'The Carved Rocks On Rombalds Moor' by the Ilkley Archaeology Group (ISBN 86181 008 2) which is a bit more cup-orientated.

Bear in mind that most rock art books don't like to theorise about meanings, but tend to content themselves being catalogues. A readable exception to this is Richard Bradley's 'Rock Art and the Prehistory of Atlantic Europe' (ISBN 0 415 16536 9 )

Generally speaking, if you can't think of a 'modern' (i.e. post roman) explanation for a cup-like mark, if there are no similar natural features on nearby rocks, then it's a contender as prehistoric. Especially if there are peck marks. People tend not to argue with peck marks.

There are allegedly some down Dartmoor. Someone on here is bound to know more of this. Where there's one or two cups, there'll be more hiding. It's a good excuse to go a-wandering on the moor ;)