Transcript The Australian Environment before Human Habitation

The Australian
Environment
before Human
Habitation
Mat Hyland
Notre Dame College
Introduction
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4.6 billion years ago the earth was
formed
Humans (Aboriginals) arrived in
Australia approx. 46 000 years
ago.
Europeans arrived 212 years ago
(1788)
The 24 hour clock!
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Imagine that time on earth fits into
one whole day (A 24 hour clock).
Seeds
4.15 billion years to 3.5 billion years
(0220hrs - 0544hrs)
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At 2.00am on the clock the planet is still in the
process of birth. The seeds are being sown.
Meteorites bombard it incessantly, and heat
from these impacts, and from atomic decay in
the planets pressurised core, fuses it into a
ball of iron-rich magma.
Rocks as old a 4.16 billion years ago have
been found at Mt Narryer in Western Australia.
Signature
3.5 billion years to 2.5 billion years
(0544hrs - 1057hrs)
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At 6.00am on the clock our solar
system was born and planets start
to orbit the sun.
Carbon atoms link to other atoms
of which some can replicate.
It is this chemistry that leaves a
faint signature on future life.
Breath of Life
2.5 billion years to 1.8 billion years
(1057hrs - 1435hrs)
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At 11.00am the world is warm and
cloudy and its surface is largely
covered by shallow seas.
Each day (one revolution) lasts
only 18 hours.
Australia at this stage consists of
two major landmasses lying
relatively close to each other
somewhere near the north pole.
Bacteria have proliferated to trigger
major environmental change.
Invaders
450 million years to 350 years
(2139hrs - 2210yrs)
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Land is still barren
Some algae have adapted to
occasional exposure to air (O2).
With the aid of root cells and vascular
stems these algae colonise the
shoreline.
Miniature forests entice animals to
follow. The first of these are millipedelike vegetarians equipped with legs and
water tight skin. However they are
short lived.
Spur of Adversity
330 million years to 200 million years
(2127hrs - 2257hrs)
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Pangaea is formed. (All the earths
land massess accumulate on one
side of the earth distupting global
weather patterns).
At 10.20pm climates become
erratic and a new ice age is born.
Crustal drift carries Gondwana (the
southern half of Pangaea) from
one side of the pole to the other.
Migration of polar ice carves is way
across five continents.
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Almost all life forms are
extinguished.
However many new species
appear.
Two survival techniques to emerge
are the “seed” and the “egg”.
Stirring the Stew
200 million years to 130 million years
(2257hrs - 2319hrs)
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At 11.00pm most of the surface is already
inhabited by a multitude of forms that are
complex and well adapted to their
environments.
The day is slightly shorter than ours, the
climate is warmer and there is little or no
snow, even at the poles.
Ancient conifers now dominate hill sides.
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Ferns and tree ferns clothe the
valleys.
Some amphibians remain and with
the evolution of the reptile egg, the
first dinosaurs emerge.
An Omen
130 million years to 65 million years
(2319hrs - 2340hrs)
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At 11.20pm a comet bursts out of the
southern skies and plunges to earth
in the very centre of Australia.
Flooding is widespread cause of high
sea levels.
Life is thriving.
Conifer, cyad and tree fern forests
cover Australian & Antarctica
supporting a large dinosaur
population.
The evolution of the flower begins.
Last Exit
65 million years to 53 million years
(2340hrs - 2344hrs)
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In the last twenty minutes of our
time scale, temperatures take their
first serious plunge since the
previous ice age.
Vegetation everywhere undergoes
massive change and a series of
extinctions begins to sweep
through the animal kingdom. This
includes the disappearance of the
dinosaurs.
Anatarctica begins to separate
from Australia after a billion years.
Great Southern Ark
53 million years to 20 million years
(2344hrs - 2354hrs)
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Birds and Mammals now dominate
as Australia recovers from one of
the worst series of extinctions in its
history.
As the temperatures continue to
descend another ice age exists.
Australia drifts north towards the
tropics.
Plants and animals are forced to
look at defence mechanisms.
They must adjust to a new climate
and a shift in Latitude of 250
Gathering Storm
20 million years to 5 million years
(2354hrs - 2358hrs)
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Australia northern edge ploughs
into the Pacific Ocean Plate,
pushing up a series of islands
known as New Guinea Highlands.
With about four and a half minutes
to go, polar temperatures take
another plunge.
Grasslands spread throughout
temperate regions and large
grazing animals poliferate. Among
these are the ancestors of modern
kangaroos and wallabies.
Fire & Ice
5 million years
(2358hrs)
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With 90 secs to go the climate is much like
it is today.
Giant mammals thrive all over the world,
however in Australia this is limited due to
lack of water. Large birds survive well.
Huge flocks of pelicans, flamingoes,
swans, ducks and other large water birds
all congregate around the shrinking
remnants of ancient inland lakes.
With 30 secs to go, world temperatures
take a final plunge into yet another ice
age.
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In Africa a new kind of “hominid”
with a top heavy brain has evolved.
Behold, This Dreamer
2 million years
(2359hrs)
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We now enter the last few seconds
on the clock.
A more distorted primate brain
evolves as humans move through
Europe and down into Asia.
Eventually two types of Humans
arrive in Australia.
 One
from Java
 The other from Chinese origin
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Aborigines prevail to become the
worlds most sophisticated huntergatherer.