Purser, B. H. 1961 Geology of the Port Waikato region (Onewhero sheet N51). Wellington: Government Print. New Zealand Geological Survey bulletin 69 35 p.
Abstract: A succession of Middle and Upper Jurassic strata, 21,300 feet thick, has been subdivided and mapped according to Marwick's (1953) biostratigraphic classification. The Puaroan Stage has been subdivided into two zones. The Huriwai plant beds at the top of the succession have been classed as a new formation. The petrography of the Jurassic sediments, and especially of the several intraformational conglomerates suggests that the parental landmass was dominantly volcanic. The Jurassic sediments have been folded, elevated and deeply eroded. A Tertairy succession ranging from Lower Oligocene to Pliocene, which thickens southwards, overlies the regional post-Hokonui unconformity. The Tertiary beds have been gently folded by an orogeny that probably began in the Miocene or Pliocene, and a resulting system of faults striking north-north-west and east-north-east has disrupted the fold pattern. Basaltic cones and flows are situated near these fractures.