CARING FOR OUR COUNTRYOutcomes: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

TOPIC OVERVIEWThere are 7 parts to this topic1. Australia’s land surfaces exhibit the effects of long

periods of weathering and erosion2. Soil as a resource that requires careful management3. Salinity of soils and water4. The effect of excessive use and long term

consequences of using some pesticides5. Maintenance of environmental flows and natural

processes in water6. The results of the Industrial Revolution on the

atmosphere and hydrosphere7. Rehabilitation and safe use of previously

contaminated sites

PART 1-LESSON 1The Development of Australian Soils

INTRODUCTION 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

INTRODUCTION Today attempts are

being made to reverse some of these negative results and to prevent further damage.

INTRODUCTION Farmers are not the only ones who have

created problems for our environment. Our cities and industry also have negative effects on the environment.

INTRODUCTION 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.

INTRODUCTION 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?

THE DEVELOPMENT OF AUSTRALIAN SOILS 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?

POOR SOILS 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.

POOR SOILS 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.

POOR SOILS Lack of weathering and erosion results in a

reduction of new sediments being transported to replenish old soils.

POOR SOILS 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.

POOR SOILS 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?

GOOD SOILS 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.

GOOD SOILS 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.

GOOD SOILS 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.

COMPARISON OF AUSTRALIAN SOILSSoil Characteristic Basalt derived

soil (Eastern Australia)

Deeply Weathered Lateritic Soil (Western Australia)

Colour Black RedNutrients Present Nitrates, Phosphates NoneMinerals Magnesiuum, zircon,

ironIron and Aluminium

Structure Blocky Thin, sandy under hardened crust

Water Retention Good PoorOrganic Content High Little or noneAge Less than 10 million

yearsUp to 300 million years

REFLECTION 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.

HOMEWORK

Read pages 109-110 HSC Spotlight TextUpdate Electronic vocabulary Complete ‘To Think About’ page 110-112Complete DOT Point 1.1 pg 54