Upper Quaternary warping and uplift rates in the Bay of Plenty and west coast, North Island, New Zealand

Abstract

Abstract Coastal terraces around the Bay of Plenty are examined from Waihi to East Cape. The tephra stratigraphy described by other authors is extended; in particular a pumiceous tephra formation immediately underlying Hamilton Ash Formation is named the Little Waihi Formation. Two terraces can be traced confidently around the Bay; the younger (BOP2) is capped by Rotoehu Ash and younger tephras and the older (BOP3) is capped by Little Waihi or Hamilton ashes and younger tephras. Wave-cut surfaces beneath the mantling deposits vary in height around the Bay, indicating warping. Near Maketu, both BOP2 and BOP3 cut surfaces are within 2 m of sea level; near East Cape they are about 50 m and 100 m, respectively. West coast terraces are traced from Kaipara and south-west Auckland into north Taranaki and thence to Wanganui. The following formations are correlated: (a) Waioneke—Waiau B—Rapanui; (b) Shelly Beach—Waiau A—Ngarino; (c) Parawai— Brunswiak; and (d) Nihinihi and upper Kaihu Formations—Kaiatea Group of T...