Journal of the Royal Society of New Zealand abstracts
Palynology, sedimentology and environmental significance of Holocene swamps
at northern Kaitoke, Great Barrier Island, New Zealand.
M. Horrocks1, J. Ogden2, S. L. Nichol3, B.
V. Alloway4, D. G. Sutton1
1 Centre for Archaeological Research, University of
Auckland, Private Bag 92-019, Auckland, New Zealand
2 School of Environmental & Marine Sciences, University of
Auckland, Private Bag 92-019, Auckland, New Zealand
3 Department of Geography, University of Auckland, Private Bag
92-019, Auckland, New Zealand
4 Institute of Geological & Nuclear Sciences, P.O. Box
30-368, Lower Hutt, New Zealand
Pollen and sediment analyses of two cores from coastal freshwater swamps at
northern Kaitoke (Kaitoke Swamp and Police Station Swamp), Great Barrier
Island, show that c. 7300 calibrated yr B.P. Kaitoke Swamp was an estuary with
tidal flats.
Avicennia, now absent from the swamp area, was present in
the estuary. By c. 4500 yr B.P. fresh water conditions had developed at the
Kaitoke Swamp site as marine influences decreased. Around the same time, fresh
water swamp conditions commenced at the Police Station Swamp site on the
surface of a low lying area of a Late Pleistocene dune. A sandy layer at
Kaitoke may represent rapid infilling followed by a dry soil surface until c.
1000 yr B.P. Conifer-hardwood forest on the hills surrounding the sites c.
7300-c. 1800 yr B.P. was dominated by
Dacrydium and
Metrosideros.
During this period, environmental conditions were relatively stable, with
little change in forest composition. Between 1800 yr and 800 yr B.P. Kaitoke
Swamp was reflooded, and the Police Station Swamp extended as a shallow lake
over the nearby dune flat. These new shallow swamps were invaded by swamp
forest (mainly
Dacrycarpus with some
Laurelia). The presence of
charcoal and
Pteridium spores above the Kaharoa Tephra suggests that
major Polynesian deforestation at northern Kaitoke began c. 600 calibrated yr
B.P.
Keywords palynology; sedimentology; Holocene; coastal
geomorphology; disturbance; Kaharoa Tephra; Rotoehu Tephra; Great Barrier
Island
(c) Journal of The Royal Society of New Zealand,
Volume 30, Number 1, March 2000, pp 27-47
PDF file of entire paper: medium quality (1235K); (scanned from paper original: notes about this process)
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