The evolution of climateBrooks, C. E. P. (Charles Ernest Pelham)
Science
The evolution of climate
Brooks, C. E. P. (Charles Ernest Pelham)
Climatology; Paleoclimatology
In the south-east a great moraine has been described at the south end
of Lake Wakatipu and others at the north-east ends of Lakes Manapouri
and Te Anau, but none are found nearer the sea-coast. The glaciated
area of New Zealand was at least ten times the present ice-covered
area, and the Tasman, the longest glacier in New Zealand, was
expanded from its present length of 16 miles to at least 30 miles.
Much of the apparent fall of temperature shown by this glaciation
was probably due to the great elevation, but apart from this the ice
had a marked influence on climate. Outside the limits of glaciation
on the east is a thick deposit of typical loess, which extends up
to a level of 1000 feet on the flanks of the hills. The occurrence
of this loess points to a steppe climate with dry, cold, southerly
winds on the lee side of the glaciated mountains, and is probably
also connected with the increase of land area. Further north, north
of Auckland in North Island, the present treeless plains were covered
by forests; for Kauri gum, apparently very old, has been found. The
sub-antarctic islands—Campbell, Antipodes, etc.—were not covered by
either New Zealand or Antarctic ice, but were the centres of local
severe glaciations of their own.
The next stage was a great subsidence, during which the glaciers
retreated. The land sank below its present level, raised beaches
probably of interglacial age being found at various heights ranging
from 10 feet above the sea at Manukau in the centre of North Island
to 150 feet at Taranaki, 200 feet at Cape Palliser, 400 feet on
the west coast of South Island, 500 feet at Amuri Bluff, and even
800 feet in the entrances to the south-western sounds. This great
submergence was associated with the deposition of extensive gravel
deposits by the rivers.
The interglacial was followed by a second period of elevation. It is
not certain how far this went. Submerged peat-bogs have been found at
a depth of nearly 600 feet below sea-level near Canterbury, but these
may belong to the early stages of the interglacial and not to the
post-Glacial period. On the other hand, the submerged forests which
are found at many points on the coast of New Zealand are evidently
post-glacial and indicate a slight rise above present level. At the
same time there was a renewal of the glacial conditions, but the ice
was confined to the valleys and had a much less extent than in the
first glaciation. This period seems to have been followed by a slight
submergence and a temporary warm period.
BIBLIOGRAPHY
David, T. W. E. “Australasie. Les conditions du climat aux époques
géologiques.” _Rep. Congr. Geol. Internat._, 10, 1906, pp. 275-98.
Süssmilch, C. A. “An introduction to the geology of New South
Wales.” Sydney, 1914.
Gagel, C. “Beiträge zur Geologie von Kaiser-Wilhelms Land.” _Beitr.
geol. Erforsch. deutsch. Schutzgebieten_, Berlin, 1913, H. 4.
Public-domain text, read in full here on John Shaqi.
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