[4] The South Island portion of Zealandia is divided from the point of view of basement rocks into an older "Western Province", consisting mainly of greywacke, granite and gneiss, down the West Coast and in a swing to Steward Island and an "Eastern Province", consisting mainly of younger greywacke and schist.

On a tributary of the East Eweburn near Naseby the stream cuts through formations that include a greater than 8 m (26 ft) thick layer of rhyolitic pumice[5][6] tuff.

The Maahunui volcanic field terminated activity 11 million years ago and is potentially associated with the similar timing Banks Volcano.

These formed by intraplate volcanism through continental crust approximately eleven to eight million years ago (Miocene).

The portion of crater rim lying between Lyttelton Harbour and Christchurch city forms the Port Hills.

[2] The Alpine Dyke Swarm of volcanic intusion took place about 25 million years ago and is located near Lake Wānaka in the Southern Alps.