Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Late Quaternary geomorphology of the Manawatu coastal plain, North Island, New Zealand Journal Paper

Clement, Alastair J.H.; Sloss, Craig R.; Fuller, Ian C.
Journal / Source
Quaternary International
Publisher / Organisation
Quaternary, Manawatu, Holocene, floodplain, estuarine deposition
This review examines the geomorphological evolution of the Manawatu coastal plain from the Last Glacial Maximum through the Holocene post-glacial marine transgression (c. 7500 cal yr BP) until the present, providing a context within which to examine the extent to which the Holocene evolution of the lower Manawatu valley follows tripartite evolutionary models of incised-valley infill. During the last glaciation the Manawatu River incised a broad, deep valley, while tributaries within the catchment dissected relict marine terraces. This occurred concurrently with the formation of a parabolic dune field at Koputaroa, with sediment sourced from the bars of the Manawatu River. During the post-glacial marine transgression rising sea-levels inundated the incised-valley. At the culmination of the Holocene marine transgression, the Himatangi anticline and Poroutawhao High restricted oceanic influences in the proto-Manawatu estuary, which was partially infilled with estuarine sediment. Estuarine deposition was quickly succeeded by fluvial deposition and floodplain due to high volumes of fluvial sediment introduced by the Manawatu River. A lack of characteristic bay-head delta development may be explained by rapid infill and consequent sediment bypass.