hhhmmmm...

I think, if the rock-art extends below ground level to a layer where the Neolithic finds are made then it might say that.

This was hinted at by a friend, so pehraps ...

The sites are on two rows of low mounds that are basically erath covered rocky outcrops. The careved stones are bedrock that protruddes from the soil. It reminded me of a couple of serpents' backs, complete with dorsal spines running across the landscape.