[1] Known locally as The Bluff,[2][3] it is set in a 495 hectares (1,220 acres) scenic reserve and rises 459 metres (1,506 ft) above sea level.

Studies using remote sensing indicate these basalt layers form part of an eroded basalt shield volcano, originally centered about 10 kilometers west of Maunganui Bluff, with an estimated width of 50 kilometers.

[7] Comparatively, other Miocene basalt shield volcanoes, such as those at Banks Peninsula, Dunedin, and the Auckland Islands, each spanned roughly 20 to 30 kilometers.

Maunganui Bluff consists of layered basalt flows between 2 and 10 meters thick, interspersed with thin beds of rubbly breccia and oxidized volcanic ash.

[8] Numerous vertical dikes, formed from intruding basalt lava, cut through these layers, representing fractures within the ancient Waipoua shield volcano during its formation.