C ARING F OR O UR C OUNTRY Outcomes: By the end of this topic you should be able to: Describe how Australia’s land surfaces have undergone continuous weathering and erosion at rates that are very slow in comparison to worldwide averages Explain why soil is a resource that requires careful management Explain the relationship between salinity or soils and water Explain the effect of ecessive use of fertilisers and the long term consequences Describe the importance of the maintenance of environmental flows and natural processes Describe the results of the industrial Revolution on the atmosphere and hydrosphere Describe the depletion of the ozone layer Describe the rehabilitation and safe use odf previously contaminated sites

T OPIC O VERVIEW There are 7 parts to this topic 1. Australia’s land surfaces exhibit the effects of long periods of weathering and erosion 2. Soil as a resource that requires careful management 3. Salinity of soils and water 4. The effect of excessive use and long term consequences of using some pesticides 5. Maintenance of environmental flows and natural processes in water 6. The results of the Industrial Revolution on the atmosphere and hydrosphere 7. Rehabilitation and safe use of previously contaminated sites

P ART 1-L ESSON 1 The Development of Australian Soils

I NTRODUCTION The Australian continent is very old and because of that soils are highly leached and often mineral deficient. Farmers going back as early as the first settlers have had to alter the natural environment in order to grow crops. This has caused significant damage to the environment

I NTRODUCTION Today attempts are being made to reverse some of these negative results and to prevent further damage.

I NTRODUCTION Farmers are not the only ones who have created problems for our environment. Our cities and industry also have negative effects on the environment.

I NTRODUCTION For example mining can damage and destroy environments. Towns produce huge amounts of waste that needs to be disposed of. And the burning of fossil fuels in automobiles and industry is changing the worlds climate.

I NTRODUCTION Such environmental issues are often segmented in today's news headlines. These problems are being addressed however are/should we take them seriously and are we moving fast enough?

T HE D EVELOPMENT OF A USTRALIAN S OILS Australia has some of the oldest exposed rocks in the world. This is because the Australian continent has been tectonically stable for a long time. Why has Australia been stable for so long?

P OOR S OILS Australia is located in the centre of the Indo- Australian plate. Because of this, it prevents most of the continent from coming into other continents which we know causes surface changing processes such as: uplift, mountain building, volcanism and earthquakes.

P OOR S OILS As a result of this stability, Australian rocks have had a very long time to weather and erode into soils leaving a very low relief terrain.

P OOR S OILS Lack of weathering and erosion results in a reduction of new sediments being transported to replenish old soils.

P OOR S OILS Leeching is another contributor. This is the process where soluble nutrients are transported from top layers to lower layers often into ground water where plants are unable to access them.

P OOR S OILS The ancient Australian soils have experienced weathering and leeching for up to 300 million years removing nutrients and producing fragile soils with low fertility. Does Australia have areas of good soil?

G OOD S OILS What causes good soils? In the Northern Hemisphere recent periods of glaciations has dumped large amounts of freshly ground up rocks which weather to create fertile soil.

G OOD S OILS Most of Australia’s better soils are a result of recent volcanism. About 40 million years ago Australia passed over a hot spot which created small volcanoes along the East coast.

G OOD S OILS These volcanoes are now extinct however as they erode, basalt and other volcanic rocks produce very fertile soils. Extinct volcanoes and their basaltic lavas can be found from Cairns to Melbourne.

C OMPARISON OF A USTRALIAN S OILS Soil CharacteristicBasalt derived soil (Eastern Australia) Deeply Weathered Lateritic Soil (Western Australia) ColourBlackRed Nutrients PresentNitrates, PhosphatesNone MineralsMagnesiuum, zircon, iron Iron and Aluminium StructureBlockyThin, sandy under hardened crust Water RetentionGoodPoor Organic ContentHighLittle or none AgeLess than 10 million years Up to 300 million years

R EFLECTION Long periods of leeching nutrients from the soil, low relief of the country and continental stability for hundreds of millions of years have all contributed toward the low fertility of Western Australian soils. Recent volcanic activity (10-20mya) along the East Coast of Australia has resulted in black fertile soils.

H OMEWORK Read pages HSC Spotlight Text Update Electronic vocabulary Complete ‘To Think About’ page Complete DOT Point 1.1 pg 54