Best bet out there is to find some of the dolerite boulders floating around the countryside (long black looking linear piles of boulders) and do your own thing. The dolerite might be a bit weathered, and seriously hot in the sun. Used to live in Lime Acres for a while where there are some brittle, loose ugly steps in the banded iron stone (not recommended should you see them).
Closer to Curuman there is a small dolomite wall outside a cave that is being archaeologically excavated. Can't remember if there are any feasible lines on that.
The map is pretty blank in that area!