They are formed of what is called "Papa." This is a blue, calcareous clay often found with limestone, which it somewhat resembles.

The Maori word "papa" is applied to any broad, smooth, flattish surface, as a door, or to a slab of rock.

The smooth, slab-like, papa cliffs are often curiously marked--tongued and grooved, as with a gouge, channelled and fluted.

Sometimes horizontal lines seem to divide them into strata.

Again, the lines may be winding and spiral, so that on looking at certain cliffs it might be thought possible that the Maoris had got from them some of their curious tattoo patterns.