New Zealand Journal of Geology and Geophysics abstracts
Geomorphological evidence for a Pleistocene barrier at Matakana Island, Bay
of Plenty, New Zealand
M. J. SHEPHERD
H. D. BETTS*
Department of Geography
Massey University
Private Bag 11222
Palmerston North, New Zealand
B. G. MCFADGEN
Science and Research Division
Department of Conservation
P.O. Box 10420
Wellington, New Zealand
D. G. SUTTON
Centre for Archaeological Research
The University of Auckland
Private Bag 92019
Auckland, New Zealand
*Present address: Landcare Research, Private Bag 11052, Palmerston North, New
Zealand.
Abstract New Zealand's largest barrier island, Matakana
Island, consists of an elongate coastal sand barrier of Holocene age that
encloses Tauranga Harbour and adjoins an area of Pleistocene terraces and
terrace remnants. The lowest Pleistocene terrace is well preserved, with a
degraded marine cliff, vestiges of shore-parallel relict foredunes, and a
parabolic dune. These hitherto unrecognised coastal landforms are analogous to
those of the Holocene barrier and indicate that a prograded coastal plain
underlies the terrace. The original landforms of the coastal plain are now
mainly below sea level but survived the postglacial marine transgression
because at least 12 m of tephra accumulated on the surface, preserving the
topography, albeit in a subdued form. In a separate area of the island, the
present morphology may reflect the former presence of large parabolic dunes of
Pleistocene age. Morphological evidence indicates that coastal processes shaped
the island during both Pleistocene and Holocene times, and that the Holocene
barrier is welded to a Pleistocene "proto-barrier".
Keywords Matakana Island; Pleistocene; terraces; relict
foredunes; parabolic dunes; dunes; sea level; Tauranga Basin; barrier island
New Zealand Journal of Geology & Geophysics, 2000, Vol. 43:
579-586
0028-8306/00/4304-0579 $7.00/0 (c) The Royal Society of New Zealand
2000
PDF file of entire paper: medium quality (3599K); (scanned from paper original: notes about this process)
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