Abstract The Otaua Group of west Northland is interpreted as comprising three phases of sedimentation: (1) a locally preserved, bathyal, upward‐fining sequence of grit, sandstone, and mudstone of late Waitakian age (Harnetts Formation, new); (2) a deltaic and regressive sequence of sandstone and mudstone (Waitiiti Formation), sandstone and grit (Otueka Formation, new), and conglomerate (Waiwhatawhata Conglomerate, including the new Smoothy Member), deposited at upper bathyal to shelf depth in the late Waitakian ‐ Otaian (first cycle); and (3) a second regressive sequence of sandstone and mudstone (Pokas Formation, new) and conglomerate (Omapere Conglomerate) deposited in upper bathyal to terrestrial conditions in the Otaian (second cycle). The Otaua Group is overlain conformably and unconformably by the late Otaian‐Altonian Waipoua Subgroup of the Waitakere Group, comprising basaltic volcanics (Waipoua Basalt), which contain near‐basal lacustrine sediment in the east (Rhine Member, new) and which are over...