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Just a small portion of a
continent almost half of Australia’s size or
approximately the size of Western Europe (almost
four million square kilometers), most of New
Zealand’s land area (continent) known as Zealandia
is 93 per cent underwater.
The actual continent is uncommonly thin and long. It
extends from the nineteenth degree latitude south
(New Caledonia’s tropical north) up to fifty six
degrees south (in NZ’s south in the austere islands
of sub-antarctic).
The deep ocean basin floors consist of dense,
volcanic basalt rocks. These rocks are made on
extending ridges in the center of bodies of oceans.
Ridges that spread have large cracks in the crust of the
earth that squeeze out molten rock. These rocks cool and
spread in outward direction on the ridge’s sides weaving its
way across the floor basin.
Moving at the same speed as the growth of a
fingernail, the cooled rocks travel in the direction
of the corners of the oceans. The further away they
travel from the ridge, the heavier, colder, and
older they become. |
Upon reaching the
boundary of the plate, the rocks on the ocean floor may subduct or sink into the interior of the earth.
Continents are very stable as compared to ocean basins.
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After the rocks have sunk into the interior
of the earth, the residue that has deposited on the
ocean floor for millions of years is scoured off
onto the surface of the continent. Almost 10 times
older than the most ancient oceanic rocks,
continental rocks are mostly really old. Continents
are actually formed over hundreds of millions of
years, starting from sediments from the ocean that
are painstakingly added to basin’s edge over a
really long period of time.
Generally, continents are twenty five to thirty
kilometers thick, and are buoyant and light that
they float on the mantle of the earth, that layer of
rock that is semi-molten that lies beneath the crust
of the earth.
Because of the general thickness and bouyancy of continents, they usually ride high on
the earth’s mantle, above the water level of oceans.
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Because it is pushed by the continuously moving
ocean basins, a large portion of New Zealand’s
shallow sea beds are moving too. The seabed is
ripped apart by submarine faults, either oozing out
hot fluids rich in minerals, push the seabed
together to build a new mass of land, or tear it
apart sideways.
Movements of faults create earthquakes that cause submarine
landslides a whole lot more intense than those that occur on
land.
The continent of New Zealand is primarily made up of 2
virtually parallel ridges. These are mostly underwater and
move towards the north-west through the Pacific Ocean’s
southern region. Included in the western ridge are the
Campbell Plateau and Lord Howe Rise. The eastern ridge is
narrower and forms Norfolk Ridge, New Caledonia, the Chatham
Rise, and the New Zealand Northland peninsula.
Both the western and eastern ridges form a sea floor
approximately a thousand to a thousand and a half meters
deep, with the occasional rising above of rocky islets in
the water. These new islands help outline the edge of the
huge Exclusive Economic Zone of New Zealand.
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