[2] These volcanoes are part of the eastern Northland volcanic belt which includes the monogenetic Kaikohe-Bay of Islands volcanic field and the volcanoes of the Whangārei Heads and the Hen of the Hen and Chickens Islands which are not part of the field.

Rather the volcanoes of the Whangārei Heads are usually related to the now extinct predominantly andesitic Taurikura volcanic complex and its caldera, although the close proximity, overlap in time, and dacite eruptive centres possibly reflects a continuum.

The hilly landscape to the west of Whangārei is from uplifted Waipapa Terrane greywacke deposits from ocean floor sediments first laid down several hundred millions ago off the coast of Gondwanaland.

There are some coal measures, sandstone, and limestone from late Eocene and Oligocene (Te Kuiti Group) sediments laid on top of the greywacke basement.

On top of these contributing to many hills are often more clay like deposits originally from the floor of the Pacific Ocean of 80-25 million years ago.