The role of mass-movement in shore platform development along the Gisborne coastline, New Zealand

Abstract

Tidal shore platforms form a conspicuous part of the coastal scenery north of Gisborne, New Zealand. Some of these platforms are being extended landward under present-day conditions. Present widening results primarily from cliff-retreat by mass-movement. The coincidence in distribution of areas of wave convergence, mass-movement and shore platforms suggests a genetic connection between these marine and subaerial process and response elements. Various types of mass-movement are involved in cliff-retreat, notably slumps, flows, debris slides and soil and rock falls. While the products of such mass-movement forms are removed by wave action, extensive boulder fields on some shore platforms indicate that removal is not always complete. Not all of the shore platforms on this coast are being widened at present. Widening has ceased where active mass-movement is not occurring.