Australia
is the world’s oldest, flattest and driest populated continent.
The
main reason for its fantastic landscape and impressive rock formations
is its geological stability.
Devil's Marbles. Poster by AllPosters. Click on thumbnail
to buy
Australian Geological Stability
Away from tectonic plate boundaries, volcanoes don’t erupt and mountain
ranges don’t rise. In contrast to the neighbouring geologically
active New Zealand, Australian continent hasn’t changed,
other than
eroded, since the uplift of the Great Dividing Range 80 million years
ago.
Australian geology. Poster by AllPosters. Click on
thumbnail to
buy
This geological stability has given erosion a lot of time to
flatten
the land and expose some of
the world's oldest
rocks and most strange
rock formations,
like Twelve Apostles in Victoria, Remarkable Rocks and Murphy’s
Haystacks in South Australia, pinnacles in Nambung National Park and
Wave Rock in Western Australia; and Devil’s Marbles, Kata Tjuta and
the world’s largest monolith Ayers Rock in Uluru
Kata Tjuta National Park in the Northern
Territory.
Uluru. Poster
by AllPosters. Click on thumbnail to buy
Australian Red Desert Soil
These fantastic rock
formations are often surrounded by the reddest soils
you have probably ever seen.
It’s so beautiful and it makes the whole landscape so
colourful, particularly when the sun sets.
Australian geology. Poster by AllPosters. Click on
thumbnail to
buy
So why is it? Why is it that
in Europe the soils are black and in Australia they are red? It’s
because of the climate. Soil is the product of
rock erosion, and the erosion is caused by weathering. In cold climate,
like in Europe and most of the North America, the main form of
weathering is physical, such as jointing, frost wedging, and in places
the impact of ancient glaciers. In hot climate
like in Australia and in
south-eastern USA, the weathering is chemical. Reactions like
hydrolysis, hydration and oxidation happen – and the red colour is a
result of oxidation, more exactly – iron oxides,
just like rust.
If you
are interested in Australian geology, there is one exellent book.
It explains everything about Australia's Precambrian
as well as Gondwanan - past, through every period, and it also mentions
places (and has photos of) where in Australia you can see the different
features. It explains a lot of geology that you see when you travel
around in Australia.
It's
got great photos and it is written in a language that is easy to
understand. So it is not like a boring, hard-to-understand
geology
book, it is really reader friendly.
History of Australian Geology
Australia in the Geological
Time
Scale
During most of the Precambrian Eon all the
world's
continents were joined in the supercontinent Pangaea.
At the end of Precambrian, Pangaea broke up and formed two different
supercontinents - the northern Laurentia, and the southern Gondwana.
Australia was part of Gondwana continent roughly from Cambrian Period
until the end of Mesozoic - the era of dinosaurs (it started breaking
off in the Jurassic Period and was completely separated only during the
Cenozoic Era).
Poster by AllPosters. Click on thumbnail to buy
Australian Geology during
Precambrian
Precambrian is the oldest eon in the Earth's history, and Australia's
oldest rocks are some large old shields (cratons) in South and Western
Australia.
Australian precambrian
rocks
also contain some large orebodies and some evidence of glaciation.
Western Australia's famous stromatolites and Banded Iron Formations
also originate from this time.
Poster by AllPosters. Click on thumbnail to buy
Australian Geology during
Phanerozoic
The next eon, Phanerozoic,
started with Cambrian
Period
evolution when an amazing amount of species
evolved during only a few millions of years, something that came to be
called the ,
and the rocks we have from this period suddenly showed a big change in
fossils. It was a big step in animalCambrian Explosion.
The eastern third of Australia was under the ocean, and shallow seas
covered much of central Australia, where many Cambrian fossils can be
found in
sedimentary rocks in places like MacDonnells
Ranges in Northern Territory and Flinders
Ranges in South Australia.
Cambrian animal. Poster by AllPosters. Click on thumbnail
to buy
During Ordovician,
the eastern third of
Australia was still under the ocean, although Cape
York and Gulf
Savannah had emerged from the water. Across central
Australia, a
shallow sea called Larapinta Seaway crossed the continent from west to
east and divided it to a southern and a northern half. In the south,
near Canberra,
volcanoes were erupting.
Ordovician fossil. Poster by AllPosters. Click on
thumbnail to
buy
During Silurian,
the uplift of eastern Australia continued and most of Queensland
now emerged from
the water while New
South
Wales, Victoria
and Tasmania
remained under the water. In central and Western Australia, sand dunes
formed and sediments were laid, that later turned to sedimentary rocks
that carry the first evidence of an animal on the land in Australia.
Silurian fossil. Poster by AllPosters. Click on thumbnail
to buy
During Devonian,
eastern Australia emerged from the water, and there was a lot of
volcanism in Victoria, New South Wales and eastern and north
Queensland. In Western
Australia, sediments that later formed the limestones and sandstones of
the Kimberley
region were deposited.
Devonian. Poster by AllPosters. Click on thumbnail
to buy
Carboniferous
period was named after the carbon-bearing coal deposits that
formed
in the
Northern Hemisphere where the climate was much warmer than in the
southern Gondwanaland.
Fossils from these times represent a cold climate flora and fauna with
no coral reef. Australia was freezing cold, covered in ice and
geologically active with a lot of volcanism. It was during this period
as Australia's youngest mountain range, the Great Dividing Range,
was formed.
Permian. Poster by AllPosters. Click on thumbnail to buy
In the end of Permian
Period
the climate got warmer and after Permian
Extinction - the world's largest mass extinction
where 80% of species were wiped out, it was time for the era of dinosaurs.
It was the Mesozoic Era
and Australia continued being geologically active throughout it, with
active volcanism, and the climate continued being warm and tropical.
Triassic. Poster by AllPosters. Click on thumbnail to buy
Cenozoic. Poster by AllPosters. Click on thumbnail to buy
Only after that did the mammals get a chance to start flourishing, and Cenozoic
is the era of mammals. Only now did Australian geology
become inactive (volcanism also stopped with the exception of
Glasshouse
Mountains). And it was
only now that
Australia was completely separated from Gondwana continent.
Jurassic Park Movie
Jurassic Park is one of the
world's most
successful movies ever made. It was based on the 1990
novel
Jurassic Park written by
Michael Crichton.
The science fiction adventure movie was filmed on Hawaii and in
California, and came out in
1993. The scene is a fictional island in central America, in
an
amusement park with cloned dinosaurs. I
won't say any more, you watch
the rest of the thriller!
Note:
This site uses
British English, which is the English we use in Australia. You will
find words like "traveller", "harbour" and "realise", and they are all
correct in the language used in Australia.
Disclaimer: Although
best efforts have been made to ensure
that all the information on this site is correct,
gondwananet.com is not to be blamed should there be a mistake.
Copyright notice:
All contents of this website are strictly protected
by the Law of Copyright. What
does that mean?