Australia is in current location because of the formation and break-up of the
supercontinent Pangaea around 220 million years ago. Continental drift and plate tectonics caused the break up of Pangaea. In the short animation below, the continents
move with the plate tectonics in the asthenosphere underneath
the lithosphere.
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| Photo Animation credit of Wikipedia: Pangaea |
All three types of plate tectonics were
responsible for the break-up of Pangaea; divergent tectonic movement separated
Australia from Antarctica, creating a coastal landscape, while the
Indian-Australian plate moved northward due to convergent tectonics and
subducting under the Pacific plate. The northward movement melted the southern glacial
climate into a dry, arid landscape as Australia moves towards the equator.
In the separation of
Pangaea, the Indian-Australian plate did not converge with any other continents,
meaning Australia formed as an island because the entire continent is located
in the middle of the single large plate. Without any converging fault lines,
Australia did not form any significant mountains making present-day Australia
the flattest continent on the planet.
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| This topographic relief map of the state of Victoria, AU demostrates how minimal the elevation is. The highest point above sea level is the tiny portion of the rust red color at about 1,100 metres or 3,600 feet. Photo Credit: http://vro.dpi.vic.gov.au/dpi/vro/map_documents.nsf/pages/vic_elevation |
Since landscapes develop over millions of years, the visibility
of changes to the Southeastern Australian landscape in the next ten years would not be noticeable to
the untrained human eye. But the physical coastal landscape constantly changes due to the process of
dissolution, also called chemical weathering. The weathering process is influenced by the moon’s gravity
that creates tides, causing waves to crash into the soft sandstone coastline of
Southeastern Australia. Over the next
ten years, it is possible that some of the current "Twelve Apostles"/stacks will
collapse because the continual process of fluvial erosion. This is predictable because the current sea stacks are evidence of where the Australian coastline used to be, and has eroded to its current location. The collapse of the sea stacks will occur as the wave cut notches at the base diminishes the strength due to the undercutting and eventually the top heavy stacks will collapse into the Southern Ocean.
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| The Apostle stack that collapsed in 2006 is incredibly close to the coastline. As the coastline continues to erode, the Great Ocean Road which allows tourists to view the length and beauty of the Southeastern shore, will eventually erode into sea stacks, and collapse into the ocean below. Photo Credit: http://www.theage.com.au/articles/2005/07/03/1120329326001.html |
While the coast has frequent rainfall, the climate dramtically changes a few miles inland to desert. The extreme aridity of Australia's climate is significant because there is only one major river flowing through all of Southeastern Australia, called the Yarra River, with several tributaries that diverge throughout the region. The development of human civilization is therefore relatively sparse and settlements are generally located along the tributary banks of the Yarra River. Civilization in the next one hundred years is unlikely to spread too much further inland into the arid climate.
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| Major human civilization is all located along the banks of the Yarra River in Southeastern Australia. Photo Credit: Wikipedia: Yarra River |
The cyclical process of La Niña and El Niño that transitions about every seven years from seasonal rainfall to relatively dry, respectively, that led
to the numerous deadly fires throughout the region in the early 21st
century will likely continue for the next one
hundred years, causing severe droughts and fires that threaten lives and
property. If sea temperatures rise, the strength of El Niño will increase the severity of the dryness and fire dangers.
In the next one thousand years, the Earth could begin a shift from its current interglacial period into a glacial period. If that happens, as glaciers and polar ice caps refreeze, sea level will drop. As a coastal region, Australia will be more affected by changing sea levels. If the sea levels drop, the receding coastline would cause the current-day continental shelf to surface.
Alternately, if the sea levels rise, life will have to cope with the submersion of coastline and move further inland into the arid climates with the freshwater Yarra river deltas intermingling with the high salinity of the Pacific and Southern Oceans.
