and those of Onerahi facies in the South Hokianga district. Yet Finlay and Marwick (1947) have referred the “hydraulic limestone,” more particularly as developed in the Kaipara region, to the Mid-Bortonian stage (Mid-Eocene), so that, unless there are hydraulic limestones developed at two different horizons. Onerahi beds must be unconformable to the Otamatea ones. Suggestion of such unconformity is, indeed, presented in the writer's area at a small headland ¾ mile north of the southern end of Ocean Beach, for a matrix of argillaceous limestone indistinguishable from that typical of the Onerahi beds includes well-rounded but unsorted pebbles and boulders up to 2 ft. 6 in. in diameter of a sandstone indistinguishable from the concretionary greensandstones of Otamatea Series. (Fig. 8.) 4. Onerahi Series (? Mid-Bortonian–Mid-Eocene) The beds referred to this series by the present writer are mainly an argillaceous limestone (the “hydraulic limestone” of local usage) and occasional siliceous or argillaceous phases associated with the more calcareous rock. A greensand exposed in a small quarry at the end of Robinsons Road, which runs from Taurikura towards Ocean Beach, may also belong to this series instead of to the Otamatea Series to which it has provisionally been referred above. The inclusion of these beds with the Onerahi beds of Ferrar (1934) is based purely on lithology; as already mentioned, Finlay and Marwick (1947) have placed them in the Mid-Bortonian, but this correlation is doubtful in view of recent discoveries of the Geological Survey.* Personal communication from Mr. B. F. Hay. Though invariably greatly disordered by acute compressive forces, the Onerahi beds fail to show any decipherable structure in the writer's area, for bedding lamination is not present. A little north of Calliope wharf, near Urquharts Bay, and, to a less extent a few chains south of the outcrop of Whangarei beds towards the middle of McLeods Bay, the Onerahi beds include interesting sedimentary dykes which are dealt with in detail in a later section. 5. Whangarei Series. (Lower to Mid-Oligocene. ? Whaingaroan to Waitakian) This series includes basal conglomerates, which generally are fine in texture, argillaceous or glauconitic sandstones and limestone of varied purity which is crystalline in appearance owing to the abundance of broken echinodermal remains that it contains. The beds outcrop at Whangarei Heads wharf at the south shore of McLeods Bay, near Darch Point south-west of this, at the middle and northern shores of McLeods Bay (Fig. 10) and at various localities on the shores of Parua Bay. In contrast with the preceding Onerahi beds, they are relatively little disturbed except by faults. Ferrar (1925; 1934) has shown that folding and erosion followed the deposition of the beds of Onerahi Series, so that Whangarei strata rest unconformably either on these latter or on the Trias-Jura greywacke basement.