>Although the prominent outcrops may be older we just have no way of knowing that.

But dare we infer it by ethnographic comparison with say, Australian ancient RA?

No. 'Cos then we'd get told off. 'Cos ethnographic comparisons are verboten, as they don't prove anything.

However, it ain't gonna stop me wondering how much closer to being able to devise a provable theory we'd be if such comparisons were used as a kind of halfway-house between random conjecture and proof.