On
this page are some facts
about soil in Australia.
So why are the soils
red in Australia,
while the soils of many other parts of the world are black or grey?
The nature of soil depends on many factors like climate, time,
composition of the rock from which the soil forms, and others.
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In cool climates the
rock weathering is mainly physical, while in hot climate, chemical
weathering is more common.
One form of chemical weathering is
oxidation, and most of Australia has got a perfect dry oxidising
environment. It is the oxides that make the soil (and the rock from
which the soil forms) red.
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Another factor is time. Large areas in the Northern Hemisphere
experienced "recent" ice ages where glaciers scraped off the soils and
exposed the bedrock as they moved. There, the soils are only 1-2m thick
and no more than 5000 years old.
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With the exception of Tasmania
and parts of Victoria,
Australia hasn't "recently" (geologically
speaking)
been affected by ice ages, and most of Australian soils are very thick
and millions of years old, so the remnant iron oxides have accumulated
after millions of years of weathering. But no matter how colourful the
red soils make the landscape, there is not much use of them because
they are very poor in nutrients. The black soils of Northern Hemisphere
are much richer in organic matter than the red soils of Australia.
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.
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