Geomorphological evidence for a Pleistocene barrier at Matakana Island, Bay of Plenty, New Zealand

New Zealand's largest barrier island, Matakana Island, consists of an elong ate coastal sand barrier of Holocene age that encloses Tauranga Harbour and adjoins an area of Pleistocene terraces and terrace remnants. The lowest P leistocene terrace is well preserved, with a degraded marine cliff, vestige s of shore-parallel relict foredunes, and a parabolic dune. These hitherto unrecognised coastal landforms are analogous to those of the Holocene barri er and indicate that a prograded coastal plain underlies the terrace. The o riginal landforms of the coastal plain are now mainly below sea level but s urvived the postglacial marine transgression because at least 12 m of tephr a accumulated on the surface, preserving the topography, albeit in a subdue d form. In a separate area of the island, the present morphology may reflec t the former presence of large parabolic dunes of Pleistocene age. Morpholo gical evidence indicates that coastal processes shaped the island during bo th Pleistocene and Holocene times, and that the Holocene barrier is welded to a Pleistocene "proto-barrier".