The Rakaia terrane rocks, of Permian to late Triassic age (300–200 Ma), occur south of Rangiora.

At the boundary between these two terranes is the Esk Head Belt, an 11-kilometre (6.8 mi) wide mélange of broken and deformed rocks.

The greywacke of the Torlesse composite terrane was deposited on the eastern side of New Zealand from the Late Carboniferous through to the Middle Cretaceous.

At the end of the canyon the turbidity current spreads out and creates giant fans of sediment that blanket the deep seafloor.

These sediments may have derived in part from the granitic rocks of northeastern Australia, as suggested by studies of the mineral grains.