Kupe's Sail is on the eastern shore of Palliser Bay, about two-thirds of a mile north-west of Cape Palliser. The name was originally applied to two triangular patches of light-coloured cliff showing against the green vegetation of the surrounding hills. The original Maori spelling is Nga-ra-o-Kupe (the sails of Kupe) and the story connected with this, according to Percy Smith (History and Traditions of the Maori of the West Coast, North Island of New Zealand, prior to 1840, Polynesian Society, 1910, p. 40) is that Kupe and his companion Ngake were camped here on one occasion, when a contention arose as to who could succeed in first completing a canoe sail (ra). So each started to work in the evening to make a sail; Kupe had finished his a little after midnight, whilst Ngake did not complete his until dawn. Thus Kupe won. The sails were then hung up against the cliffs “and may be seen there to this day”.
Both patches of light-coloured cliff are composed of outcrops of late Miocene sandstone (about 12–14 million years old) dipping seawards at an angle of 45 degrees. The sandstone is compacted and well bedded, and one of the patches, immediately east of the mouth of Kupe Stream, is a very prominent dip slope. Nowadays the name “Kupe's Sail” is more usually applied to this outcrop in particular. Abundant marine fossils are in the sandstone and similar beds occur in Hurupi Stream and Putangirua Stream further to the west around Palliser Bay.
The light-coloured sandstone rests unconformably on dark-coloured greywackes and argillites which continue northwards to form the Aorangi Mountains. The greywackes and argillites are unfossiliferous, but are thought to be of early Cretaceous age (about 130 million years old). In Kupe Stream these rocks are intruded by igneous rocks; pillow lavas (altered submarine basalt flows) and tuff beds are interbedded with them at Cape Palliser. The sandstone has been tilted down along a north-east-trending fault cutting the coast close to the mouth of Kupe Stream. This down-tilting has preserved the sandstone along the fault line. Late Miocene beds formerly covered most of the greywacke and argillites of the Aorangi Mountains, but subsequent uplift and erosion have removed most of them except on the flanks and where they have been downfaulted, as at Kupe's Sail.
by Graeme Roy Stevens, M.SC.(N.Z.), PH.D.(CANTAB.), Paleontologist, New Zealand Geological Survey, Lower Hutt.