Trias-Jura rocks of the Awakino-Mahoenui area constitute part of the western limb of the Kawhia Syncline in its southern-most exposure. The syncline is approximately meridional in alignment and pitches northwards at a low angle. Strata have dips varying from nearly vertical in the west of the area to about 15° east at the top of the succession in the east. The strata form the Herangi Range which originated as a north-south fold or the peneplained surface resulting from the post-Hokonui orogeny. This fold is believed to be faulted on its western edge, but while this is also the case on the eastern limb farther north, in the Awakino-Mahoenui area faulting seems not to have occurred at the surface.