Textbook Geoactive 2 (chapter2)

GEOactive 2

18

Yellow-footed rock wallaby and baby,Flinders Ranges, South Australia

No country in the world is the same as another,but Australia is particularly rich in physical characteristics that make it unique. In this chapter, we focus on the physical environment, including major landforms and drainage basins, patterns of climate, vegetation and natural resources, and flora and fauna.

A student:5.1 identifies, gathers and evaluates geographical

information5.2 analyses, organises and synthesises geographical

information5.3 selects and uses appropriate written, oral and graphic

forms to communicate geographical information5.4 selects and applies appropriate geographical tools5.5 demonstrates a sense of place about Australian

environments5.6 explains the geographical processes that form and

transform Australian environments5.10 applies geographical knowledge, understanding

and skills with knowledge of civics to demonstrate informed and active citizenship.

Using physical maps (page 23) Using topographic maps (page 25) Interpreting contour patterns (pages 267) Using vertical aerial photographs and topographic

maps (page 28) Interpreting climatic graphs (page 33) Interpreting synoptic charts (page 35) Using area and grid references (page 42)

Chapter 2

PHYSICAL CHARACTERISTICS

THAT MAKE AUSTRALIA UNIQUE

CHAPTER 2: PHYSICAL CHARACTERISTICS THAT MAKE AUSTRALIA UNIQUE

19

climate: the long-term variation in the atmosphere, mainly relating to temperature and precipitation

deposition: the laying down of material carried by rivers, wind, ice, ocean currents or waves

drainage basin: the area of land that feeds a river with water or the whole area of land drained by a river and its tributaries

drought: a period of below average precipitationecosystem: a system formed by the interactions of

the living organisms (plants, animals and humans) and physical elements of environments

endemic: native to a particular area and found nowhere else

erosion: the wearing away of soil and rock by natural elements such as wind and water

isobars: lines drawn on a map joining places of equal barometric pressure

marsupial: a mammal that keeps and feeds its young in a pouch for a few months after birth

mass movement: the movement of rock and soil down a slope due to gravity

monotreme: mammal that lays eggs; the only species are the platypus and echidna

monsoon: the seasonal change in wind direction that is experienced in much of the tropics

regolith: the layer of broken rock and soil on top of the solid rock of the Earths crust; also known as mantle rock

renewable resources: resources that can be replaced in a relatively short amount of time (for example, trees)

salinity: the presence of salt on the land surface, in soils or rocks, or dissolved in water in our rivers or ground water

species: a group of plants or animals of the same kind, able to breed with each other

synoptic chart: weather map that uses isobars and other symbols to show the movement of weather systems and patterns of temperature and rainfall

tectonic: refers to the forces or conditions within the earth that cause movements of the crust such as earthquakes, folds, faults and volcanoes

topography: physical features of an area of land its height and shape

unique: unlike anything else; the only one of its typeweathering: the breakdown of bare rock by water

and temperature changesWorld Heritage List: areas designated as being of

global importance for conservation and study

GEOactive 2

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The tectonic forces of folding, faulting and vol-canic activity have created many of the majorlandforms of Australia. Other forces that workon the surface of Australia and give our land-forms their present appearance are weathering,mass movement, erosion and deposition.

Weathering is the breakdown of bare rock bywater and temperature changes at the Earths sur-face. On a continental scale, weathering contri-butes to the development of only minor landforms.Its main impact is in the way it converts solid rockinto a layer of regolith, or broken rock and soil,which is more easily moved by other processes.

The gravitational movement of rock and soildownslope is called mass movement. This con-tributes to the appearance of local landforms. Forexample, the steep sides of parts of the BlueMountains are formed by a combination ofweathering and mass movement.

The main force that has created the presentappearance of our topography is erosion.Erosion is the wearing away of soil and rock bynatural elements, such as water, ice and wind.Water erosion by rivers and streams has beenresponsible for the carving of many valleys inAustralias higher areas. Small parts of the Aus-tralian Alps and Tasmania have been eroded byglaciers during the last Ice Age. Drier parts ofAustralia have experienced some wind erosion.

When streams, glaciers and winds slow down,they deposit or drop the load of rock, soil andparticles they have been carrying. This is calleddeposition. Many broad coastal and low-lyinginland valleys have been created by stream depo-sition. These areas are called flood plains. Winddeposition has created many sand dunes alongbeaches and in desert areas.

The topography or landforms of Australia can bedivided into four major regions: the CoastalPlains, the Eastern Highlands, the Central Low-lands and the Western Plateau. The Coastal Plains around Australias edge are

narrow and discontinuous. The plains oftentake the form of river valleys, such as those ofthe Fitzroy River near Rockhampton and theHunter Valley near Newcastle.

MAJOR LANDFORM REGIONS

The Eastern Highlands region (which includesthe Great Dividing Range) is mainly a series oftablelands and plateaus. Most of the area isvery rugged because rivers have cut deep val-leys across it. It is the source of most of Aus-tralias largest rivers including the Fitzroy,Darling and Murray. The highest part is in thesouth-east where a small alpine area is snow-covered for more than half the year.

Australias highest mountain is Mount Kosciuszko at2228 metres. Mount Everest the worlds highestmountain is 8848 metres.

The Central Lowlands is a vast area of veryflat, low-lying land which contains three largedrainage basins: the Carpentaria lowlands inthe north, the Lake Eyre basin in the centre,and the MurrayDarling basin in the south.

The Western Plateau is a huge area of table-lands, most of which is about 500 metres abovesea level. It includes areas of gibber (or stony)deserts and sandy deserts. There are severalrugged upland areas, including the Kimberleyand Macdonnell ranges.

2.1MAJOR LANDFORMS AND

DRAINAGE BASINS

Australias four major landform regions

0 250 500 750 km

Plains

Highlands

Western Plateau

Central Lowlands

Eas

tern

Hig

hlan

ds

Eastern Highlands

Tropic of Capricorn

N

Coastal Plains


21

King George Falls, the Kimberley. The King George River flows across the Western Plateau then plunges 60 metres over the eroding edge of the plateau into the ocean.

SAMPLE STUDYThe MurrayDarling basinThe MurrayDarling basin covers about one millionsquare kilometres and is drained by more than 20major rivers. It has a large variety of environments,ranging from alpine areas in the east to rangelandsin the west. The basin produces one-third of Aus-tralias food and 40 per cent of Australias total agri-cultural income. It supports one-quarter of thenations cattle, half the sheep and makes up almostthree-quarters of the irrigated land in Australia.

The MurrayDarling drainage basin is the largestand most important in Australia, but it is small byworld standards. The amount of water flowingthrough it in one year is about the same as theAmazon Rivers flow in one day.

The basin is facing severe problems: Only about 20 per cent of water flowing through

the basin ever reaches the sea. The rest isdiverted for agriculture, industry and domesticuse. In 1981 the Murray mouth closed for thefirst time since European settlement. It hap-pened again in 2002 and will probably closemore often unless natural flows are increased.

The Murray supplies about 40 per cent ofAdelaides drinking water. Within 20 years, ifwater quality continues to decline, salinitylevels will exceed World Health Organizationlimits for safe drinking water.

Approximately 5080 per cent of wetlands in thebasin have been severely damaged or destroyedand more than one-third of native fish speciesare threatened with extinction.

1. Briefly explain what is meant by the following terms: weathering, mass movement, erosion and deposition.

2. Which of these processes has been the most significant in the development of Australias landforms?

3. Observe the map of Australias major landform regions.(a) What are the four major landform regions?(b) Which region is:

(i) the largest? (ii) the smallest?(c) State the landform region in which each of the

following is located (refer to an atlas if necessary):

4. Name Australias largest drainage basin.5. What is the approximate size of the MurrayDarling

drainage basin?6. The MurrayDarling basin has a large variety of

environments. Explain how this would affect the potential for agriculture.

7. Why has the basin developed into such an important irrigation area?

8. Form small groups to use the Internet and/or library to research the problems facing the MurrayDarling basin. What could be done by individuals, groups and governments to improve the situation? Prepare a report and have one member present it to the class. To find out more, go to www.jaconline.com.au/geoactive/geoactive2 and click on the MurrayDarling Basin weblinks for this chapter.

Worksheets2.1 River systems

(i) Sydney(ii) Alice Springs(iii) Canberra

(iv) Kalgoorlie(v) Cairns(vi) Lake Eyre.

Timor Sea

Lake Eyre

Western PlateauIndian Ocean

Timor Sea

Gulf ofCarpentaria

North-eastCoast

BullooBancannia

MurrayDarling

South-eastCoastSouth Australian

Gulf

Tasmania

23.3%

23.3%

1.0%

1.7%

0.4%

0.2%

13.3%

10.6%

6.1%

0.3%

1.6% 21.1%

23.3%

Water catchment area name

Distribution of Australias run-off

0 250 500 km

South-westCoast

N

Australias drainage basins

GEOactive 2

22

Permanent rivers and streams flow in only asmall proportion of the Australian continent. Infact, Australia is the driest of all the worldsinhabited continents. It has: the lowest amount of run-off the lowest percentage of rainfall as run-off the least amount of water in rivers the smallest area of permanent wetlands the most variable rainfall and stream flow.

The MurrayDarling is Australias largestriver system. Other significant rivers are: the Burdekin River in Queensland the Hunter River in New South Wales the Murchison, Gascoyne, Ashburton, Fortescue,

De Grey, Fitzroy, Drysdale and Ord rivers in thenorth-west region

the Victoria and Daly rivers in the NorthernTerritory

the Leichhardt, Norman, Gilbert and Mitchellrivers in the Gulf of Carpentaria

the Tamar, Derwent and Gordon rivers ofTasmania, although these are relatively short.Australia has many lakes but they hold little

water compared with those found on other conti-nents. The largest are Lake Eyre and Lake Torrensin South Australia. During dry seasons, thesebecome beds of salt and mud. Yet an inland sea didonce exist in this area. It covered about 100000square kilometres around present-day Lake Eyreand Lake Frome. South Australia is the driest stateand has very few permanent rivers or streams.

RIVERS AND LAKES

Satellite image of Lake Eyre, March 1985. Once a freshwater lake, the region is now an evaporated saltpan. The crust of salt is shown as white in the image.

Satellite image of Lake Eyre, February 1984. Three or four times each century, the lake fills with water, transforming it into a haven for wildlife. Deep water is shown as black in the image.

Sour

ce:

Com

mon

wea

lth o

f Aus

tralia

, Lan

dsat

MSS

/TM

/ETM

sat

ellit

e im

ages

acq

uire

d by

ACR

ES, G

eosc

ienc

e Au

stra

lia. A

ll rig

hts

rese

rved

. Rep

rodu

ctio

n by

per

mis

sion

of t

he C

hief

Exe

cutiv

e Of

ficer

, ww

w.g

a.go

v.au

.

N

Van

Lake Argyle

King Sound

Roebuck Bay

Shark Bay

JosephBonaparte

Gulf

Geographe Bay

I N D I A N

O C E A N

T I M O RS E A Cape Ford

Cape Naturaliste

Cape Londonderry

Cape Leveque

Steep Point

HoodPointCape Leeuwin

BathurstIsland

Archipelago ofthe Recherche

Barrow Island

TimorSumba

Houtman Abrolhos Islands

LombokJava Bali

FloresSumbawa

0 200 400 600 800 km

Tropic of Capric

orn

TanamiDesert

S t u r tP l a i n

N or t

h W

e st S

h el f

HAMERSLEY RANGECARNARVON RANGE

Mt Meharry 1249 m

LakeDisappointment

G i b s o n D e s e r t

Lake Carnegie

D e s e r t

Lake Carey

Lake Lefroy

UNL L

A RB O

R

LakeBarlee

Lake Austin

K I M B E R L E Y

Mur

chis

on

River

RiverGascoyne

Fortescue River

Riv

erFitzroy

Victor

Percival Lakes

G r e a t S a n d yDe s e r t

Lake Gregory

Image WorldSat International Inc., 2001 www.worldsat.ca All rights reserved.Overlay by MAPgraphics Pty Ltd, Brisbane.

Desert

Forest

Lake

Mountains

Islands

River Sea mounts

Australia physical map


23

Using physical mapsThe natural features of a region are shown on physical maps. Mountain ranges, plateaus, rivers, seas and other physical features are highlighted. Information about towns and cities is kept to a minimum.

1. Observe the physical map of Australia and list the following:(a) the three highest mountain peaks in the Great

Dividing Range (b) two deserts in the Central Lowlands(c) four mountain ranges on the Western Plateau(d) three rivers in the MurrayDarling drainage

basin(e) three rivers in the

Indian Ocean drainage basin (see map on page 21).

2. Using information from the map, explain why Lake Torrens and Lake Eyre usually contain so little water.

3. Use information from the text and from the map to explain why the MurrayDarling river system has a small discharge for the size of its catchment and length.

4. On an outline map of Australia complete the following.(a) Draw the Great

Dividing Range and the MurrayDarling basin onto your map.

(b) Add Mount Kosciuszko to your map.

(c) Shade the areas of desert.

(d) Show the location of four seas near Australia.

(e) Show the approximate location of the area shown in the photographs on page 22. Add a label for this place.

(f) Provide a title, scale and key for your map.

(g) Use the scale to estimate the width of Australia at its widest point and the distance from the most northerly point of Australia to the most southerly point.

TOOLBOX

Lake Yamma Yamma

Buck

ingha

m

Ba

y

Torres Strait

Shelburne Bay

PrincessCharlotte

Bay

BroadSound

Lake Pedder

Spen

cer

Gul

f

Port Jackson

Moreton Bay

LakeWoods

P A C I F I CO C E A N

S E A

T A S M A NS E A

NGES

FL

IND

ER

S

RA

NG

ES

Mt Kosciuszko 2228 m

DAVENPORTRANGE

Mt Bartle Frere1611 m

Mt Bogong1986 m

Mt Woodroffe1440 m

South East Cape

Cape Arnhem

Cape NelsonCape Otway

Cape Howe

Cape Byron

Cape York

Tasmania

EyrePeninsula

CobourgPeninsula

King Island FurneauxGroup

Fraser Island

ThursdayIsland

MorningtonIsland

Groote Eylandt

Wessel Islands

KangarooIsland

Lord Howe Island

Moreton Island

New Guinea

G u l f

o fC a r p e n t a r i a

P A C I F I C

O C E A N

C O R A L S E A

B a s s S t r a i t

GR

EA

T

BA

R

RI E

R

RE

EF

Cape

Yo r k

Pen i nsu l a

A r n h e mL a n d

BA

RK L Y T A B L E L A

ND

L A I N

NGES

Rive

r

Darli

ng

Riv

er

River

Lach

lanRiver

Murray River

yMt Liebig1524 m

Uluru 868 m

Lake Amadeus

LakeEyre

Lake TorrensLakeFrome

Lake Gairdner

Sturt StonyDesert

Simpson Desert

Rive

r

Dia

man

tina

Georgina R

iver

GR

EA

TD

IV

ID

IN

GR

AN

GE

G RE A

TD

I VI D

IN

GR

AN

GE

Murrumbidge e

GEOactive 2

24

A topographic map is a map that shows theactual shape of the landscape and the variousheights of the landscape. The map allows geog-raphers to see the height and shape of the landby using contour lines. Contour lines are linesthat join together all points that have the sameheight above sea level. The height between con-tour lines is called the contour interval. The mapon the opposite page has various contour lineswith an interval of 50 metres. The numbers onthe contours show how high the land is above sealevel. Mount Florence, for example, is more than400 metres above sea level.

The map also shows that some contour lines areclose together while other contour lines are farapart. Close contours mean that the slope of theland is steep; contours well apart mean that theslope of the land is gentle. The closer the contours,the steeper the slope. The further apart the con-tours, the flatter the slope. Therefore, on the mapon this page, the land around X is steeper thanthe land around Y. The relative steepness of theslope is called the gradient.

Topographic maps also show in detail both thenatural and human features of the landscape.Natural features include rivers, lakes, swamps,hills and beaches. Human features include roads,towns, railways and dams. Topographic maps useconventional signs and symbols to show water,rivers, vegetation, roads, railways and buildings.The meaning of each sign or symbol is explainedin a key, or legend.

ColoursDifferent colours are also used on topographicmaps to indicate certain features, for example: brown is used for natural features, including

contour lines blue is used for all water and river features green is used for vegetation and ground cover black and red are used for human features

such as roads, railways and buildings.

CONTOURS

LEGEND

Topographic maps also use lines to help us locateplaces on a map. These lines are overprinted toform a grid. These grid lines are given as two-digit numbers that appear on the margins of themap. The lines that run up and down the map(northsouth) are called eastings because thenumbers increase the further east they are. Thelines that run across the map horizontally (eastwest) are called northings because the numbersincrease the further north they are. Whenstating location, the eastings are given first, thenthe northings.

Area references and contour lines on a topographic map

An area reference is a four-figure reference thattells us the grid square in which to find afeature. On the map opposite, the railway stationis located at 8640. The letters AR are usuallyplaced in front of an area reference, so the areareference for the railway station is AR8640.

A grid reference is a six-figure number thatshows an exact point in the grid square. Thethird and sixth figures represent one-tenth ofthe distance between the two grid numbers.However, these divisions are not written on themap, so they must be estimated. The letters GRare used in front of a grid reference. The gridreference for point Y on the map above isGR643146. There are no spaces between thedigits in references.

AREA AND GRID REFERENCES

14

13

12

11

60 61 62 63 64 65

350

Y

X

400

400

450

450

500550600

2.2TOPOGRAPHIC

MAPS


25

Using topographic mapsThe map below is a topographic map showing contours, grid references and a legend. Observe the map carefully and answer these questions.

1. What is the area reference for each of these points marked on the map? The first one is done for you.

2. What are the grid references for the same points? A is GR835486.

3. In which direction would you have to travel to reach point D from:

(a) A is AR8348.(b) D(c) G(d) B

(e) E(f) H(g) C(h) F

(a) B? (b) C? (c) E?

4. Using the legend, what is at each of these points?

5. What is the height of the land at points B, C, F and G on the contour map?

6. How high is Mount Florence? Which side of Mount Florence is the steepest?

7. If you walked from the railway station to Mount Florence:(a) would you be travelling uphill or downhill?(b) which part would be the flattest section of

your journey?(c) how many metres would you have to walk to

reach Mount Florence?8. Which human features can be found at the

following area references?(a) AR8640 (b) AR8940 (c) AR8441

9. Measure the distance between GR802440 and GR890453.

(a) A(b) B

(c) C(d) D

(e) E(f) F

TOOLBOX

A simple topographic map

Contour interval: 50 metresScale: 1 cm = 500 m

48

47

46

45

44

43

42

41

40

80 81 82 83 84 85 86 87 88 89 90 91 92 93

LEGEND

Built-up area

Railway

Lake

Swamp

Sealed road

Mountain

Stream

Height in metres250

E

G

BC

D

400

350

150

300

250

200

250

200

H

Railwaystation

Johnsville

F

N

Mt Florence

Dea

d Dog C

reek

A

GEOactive 2

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Interpreting contour patternsTopographic maps are used by many people for different purposes. They are used by surveyors, engineers, bushwalkers, real estate developers, geologists and by anyone who simply wants to have a detailed knowledge of a particular area. Many topographic maps were originally surveyed

for military purposes and were often referred to as military maps.

As you become more familiar with contour lines, you will be able to see the shape of the land just by looking at a contour map. Common features such as hills, cliffs, plateaus, valleys, ridges, spurs and saddles can be identified by their contour patterns. Some of these are identified in the map and illustrations below.

TOOLBOX

1000 800

600400200

200

400

400600 80

0100

0

1160

1000

800

600

400

600

850

N

2000 400 metres

1100

An extensive area of flat land that is higher than the land around it. Close contours surround a wide area that has no or few contours.

PLATEAU

ROUND HILL

A high round piece of land, not as large as a mountain. Contours form a circle or oval shape.

A high, steep, rocky slope formed by erosion or earth movements. Contours are on top of or nearly on top of each other.

CLIFF

Low land between hills or mountains. It usually has a river flowing through it. Contours form a U- or V-shape that points towards high land.

VALLEY

An area of land that sticks out like a finger from the side of a mountain or hill. Contours form a U- or V-shape that points away from high land.

SPUR

SADDLE

Two areas of high land with a dip between them. It is shown by two circular or sausage-shaped contours with a gap between them.

Long narrow hilltop. Closely spaced contours form a long sausage shape.

RIDGE

DELTA

OCEAN

2.3CONTOUR PATTERNS


27

Observe the Grampians map extract. Give the six-figure grid reference for:

(a) a cliff (b) a valley (c) a spur (d) a saddle (e) a ridge.

Topographic map extract of the Grampians, Victoria Commonwealth of Australia, Geoscience Australia. All rights reserved.

GEOactive 2

28

Katherine Gorge is located in Nitmiluk NationalPark in the Northern Territory. Vertical faults inthe ancient sandstone plateau have been deeplyeroded by the Katherine River, forming spec-tacular landforms including Katherine Gorge.Volcanic activity also occurred in this region inthe past. It has resulted in younger areas ofharder volcanic rock intruding into the oldersandstone. Many rapids and waterfalls haveformed along the river because the river haseroded areas of harder rock more slowly than thesofter sandstones.

Using vertical aerial photographs and topographic mapsVertical aerial photographs and topographic maps are very useful tools for the geographer. They give a clear visual impression of physical and human features of the landscape. (Find out more about topographic maps on pages 245.)

Observe the vertical aerial photograph and the topographic map and answer the following questions.1. Draw a sketch map of the area shown on the

aerial photograph using a colour key to show higher land, lower land, rivers, gorges and the escarpment.

2. Which features stand out on the aerial photographs due to shadows?

3. At what time do you think the aerial photograph was taken?

4. Find Katherine Gorge on the topographic map.(a) What symbol is used to show the gorge on the map?(b) Why has this symbol been used instead of contour lines?

5. Give a six-figure grid reference for every waterfall on the map.6. What type of vegetation dominates the region?7. In what direction would you be walking if you travelled from

Mount Shepherd (GR244074) to the following places?(a) The rock column (GR297054)(b) The river gauging station (GR194196)(c) The rapids (GR276160)

8. Use the scale to calculate the straight-line distances for each of the trips mentioned in question 7.

9. Name two human and two physical features of the environment at AR2115.

Worksheets2.2 Pick a landform Location of Katherine Gorge

TOOLBOX

Vertical aerial photograph of Katherine Gorge

an Diemen

Chambers Bay

Port Darwin

Clarence S

trait

Anson Bay

Daly

Adela

ide

Rive

r

Rive

r

RiverRoper

Dundas StraitVa n D i e m e n

G u l f

A R A F U R A S E A

RiverAlligator

Sth

(Katherine Gorge)National Park

2.4UNDERSTANDING LANDFORMS:

KATHERINE GORGE


29

Topographic map of Katherine Gorge Commonwealth of Australia, Geoscience Australia. All rights reserved.

GEOactive 2

30

The size and location of Australia ensures thatit has a wide range of climates. These can beseen on the map of climatic zones. Australia iswidely known as the dry continent. Around80 per cent of Australia has a rainfall of lessthan 600 mm per year and 50 per cent has lessthan 300 mm. Not only is the rainfall low but itis highly variable and droughts are a commonoccurrence.

Australian climatic zones

The main reason Australia is so dry is that muchof the continent lies in an area dominated byhigh pressure for most of the year. High pressuresystems drift from west to east across the conti-nent bringing dry, stable, sinking air. Thisresults in atmospheric conditions that are notfavourable for rainfall (see the weather map onthis page).

CLIMATE AND RAINFALL

PRESSURE SYSTEMS

Of all the inhabited continents, Australia has the lowest average yearly rainfall.

The movement of high pressure systems across the continent is the main reason why Australia is so dry.

As the rainfall maps opposite show, the wettestparts of Australia are the northern and easterncoastal areas and the west coast of Tasmania.

The northern part of Australia generally has asummer rainfall maximum. In summer, a troughof low pressure extends south from the Equatorand brings moist, unstable air in north-westerlywinds over the area (see the weather map).

Australia Eurasia NorthAmerica

Africa SouthAmerica

1800

1500

1200

900

600

300

0

Ave

rage

ann

ual r

ainf

all (

mm

)

Rainfall

H

2.5AUSTRALIAS PATTERN

OF CLIMATE AND VEGETATION

summers; dr

m all year; dr

pical wet and dr

m all year; dr


31

This can lead to widespread rain, particularlynear the coast. This is often referred to as thenorth-west monsoon.

A summer low pressure trough brings rain to northern Australia.

Also during the summer and autumn, tropicalcyclones can develop off the coast of northernAustralia and bring heavy rain, especially tocoastal areas. During winter much of the area isdominated by high pressure systems that havemoved further north. Dry and stable air from theinterior of Australia dominates the area andthere is little rainfall.

The southern part of Australia generally has awinter rainfall maximum. During winter, coldfronts in association with low pressure systemsmove further north over this area and bring coolmoist air and rain as the cold fronts passthrough. The heaviest rain falls on the coastalmargins, including the west coast of Tasmania.

The passage of a cold front over southern Australia in winter brings cool, moist air.

HH

Trough

H

H

L

The east coast receives rainfall throughout theyear. Much of this rain is brought by moist east-erly winds. The heavier falls of rain are generallyconfined to the coast and highlands as thewestern side of the highlands lies in a rain-shadow area from the moist easterlies.

Average rainfall in Australia for January and July

Average monthly rainfall (mm)

Perth

Darwin

Adelaide

Melbourne

Canberra

Sydney

Brisbane

Hobart

Perth

Darwin

Adelaide

Melbourne

Hobart

Canberra

Sydney

Brisbane

0 600 1200 km

0 600 1200 km

200 to 400

100 to 200

50 to 100

25 to 50

10 to 25

0 to 10

No rain

Over 400

January

July

N

N

Tropic of Capricorn

Tropic of Capricorn

JANUARY

JULY

GEOactive 2

32

The maps show the seasonal distribution oftemperature in Australia for January and July.Variations in temperature occur for severalreasons. One reason is that, at higher latitudes onthe Earths curved surface, solar radiation (heatfrom the sun) is spread more widely than at placesat lower latitudes (see the diagram). The suns raysthat reach the Earth near the Equator (that is, atlow latitudes) have a smaller area to heat than raysreaching the Earth at higher latitudes. Thisexplains why Darwin experiences higher tempera-tures than Melbourne (refer to the climatic graphs).

Places inland tend to be warmer in summerand cooler in winter than places on the coast.This is because of the moderating effect of theoceans on temperature. The oceans heat and coolmore slowly than the land and their tempera-tures vary less throughout the year. In winter,places near the ocean are warmer than placesinland, whereas in summer they are cooler.

Average temperatures in Australia for January and July

TEMPERATURE

5000

1000 km

5000

1000 km

Average temperature (C)

20 to 30Average temperature (C)

10 to 20

10 to 20

20 to 30

Over 30

0 to 10

Januar y

July

N

N

Tropic of Capricorn

Tropic of Capricorn

JANUARY

JULY

Temperatures are higher at low latitudes (closer to the Equator) because incoming solar radiation has a smaller area of the Earth to heat.

The size and latitudinal extent of Australia hasresulted in a wide variety of vegetation. The dryclimate has resulted in about 40 per cent of Aus-tralia being covered by grassland and shrubs. Inhigher rainfall areas, trees dominate. In themedium to high rainfall areas, much of thenatural vegetation has been cleared for agricul-tural and urban development.

Australian vegetation

60N

0Equator

Solar radiation

Solar radiation

AUSTRALIAS PATTERN OF VEGETATION

Rainforest

Wet eucalypt forest

Dry eucalypt forest

Mallee scrub

Mulga scrub

Mallee and Mulga scrub

Brigalow scrub

Woodland

Mountain moor

Swamp meadow

Grassland savannah

Heath

Saltbush

Desert

Vegetation type

Dry grassland short wiry grass

Dry grassland long tussock grass

0 550

1100 km

N

Tropic of Capricorn


33

1. Observe the weather map showing the movement of high pressure systems.(a) Describe the movement of high pressure systems

across Australia. (b) How do these high pressure systems contribute to

Australias dryness?2. Observe the maps showing Australias average

rainfall for January and July. (a) Moving in a line from Adelaide to Darwin,

describe the changes in rainfall that occur in January.

(b) Moving in a line from Brisbane to Perth, describe the changes in rainfall that occur in January.

(c) Moving in a line from Hobart to Darwin, describe the changes in rainfall that occur in July.

(d) Using information in the text, and with reference to the weather maps showing a summer low pressure trough and the passage of a winter cold front, explain the main reasons for the distribution of rainfall over Australia in January and July.

3. Observe the maps showing average temperatures in Australia in January and July. With the aid of an atlas:(a) rank the following towns and cities from the

warmest to the coolest for temperatures in January: Perth, Mount Isa, Mount Gambier, Hobart

(b) rank the following from coldest to warmest for temperatures in July: Alice Springs, Hobart, Darwin, Melbourne, Mackay

(c) explain why Alice Springs has higher average daily temperatures in January than Mackay, even though Mackay has a slightly lower latitude.

4. Imagine that you are a travel consultant advising agencies around the world on travel in Australia. You have received an email from a New York agency with a request for your advice on the climatic conditions a group would experience if they were visiting Perth, Alice Springs, Melbourne and Brisbane in August. Write a reply to the email (500 words maximum).

5. Observe the map of Australian vegetation. Moving in a line from Adelaide to Darwin, describe the changes in vegetation type. Account for these changes.

6. Explain how climate affects the patterns of Australian vegetation. To find out more about the relationship between climate and vegetation, go to www.jaconline.com.au/geoactive/geoactive2 and click on the Climatic Zones weblink for this chapter.

Worksheets2.3 Choropleth mapping skills

Interpreting climatic graphsA climatic graph is a combination of a bar graph and a line graph. Climatic graphs show the climateof a place over a 12-month period. The line graph section always shows average monthly temperature, and the bar graph represents average monthly rainfall. Be careful to read from the correct scale when studying climatic graphs. The right-hand scale represents average rainfall in millimetres. The left-hand scale represents temperature in degrees Celsius.

Observe the map of climatic zones on page 30 and the climatic graphs here.1. Observe the climatic graph for

Alice Springs.(a) What type of climate is this?(b) Describe the climate in

terms of temperature and rainfall.

2. Observe the climatic graphs for Perth, Darwin, Melbourne and Brisbane. (a) What type of climate does

each of these cities have?(b) Describe the climate for

each of these cities including the following: temperature; seasonal distribution of temperature; rainfall; seasonal distribution of rainfall.

3. Explain why Perth and Darwin have a different seasonal distribution of rainfall.

4. Observe the climatic graphs of Darwin and Melbourne. If you were to visit each of these cities tomorrow, what sort of weather would you expect to experience in each city? Check newspapers or go to www.jaconline.com.au/geoactive/geoactive2 and click on the Bureau of Meteorology weblink for this chapter. What is the forecast for Darwin and Melbourne? Are these normal weather conditions for this time of year?

10

20

0

30

40

0

100

200

400

300

ALICE SPRINGS

DNOSAJJMAMFJ

C

max.

min.

Average monthly temperatureand rainfall

0

10

20

30

40

0DNOSAJJMAMFJ

DARWINC


max.

min.

0

10

20

30

40

0DNOSAJJMAMFJ

max.

min.

BRISBANEC mm


0

10

20

30

40

0DNOSAJJMAMFJ

MELBOURNE mmC


max.

min.

10

20

0

30

40

0

100

200

400

300

PERTH

DNOSAJJMAMFJ

C


max.

min.

TOOLBOX

GEOactive 2

34

Weather maps, or synoptic charts, can appearrather complicated. But when you know what thelines and symbols mean you will find these mapseasy to use.

One of the most important features of the atmos-phere and one that is very frequently measured isair pressure, or the weight of the air. All air hasweight. While we cant feel it because we are con-stantly surrounded by it, sensitive instrumentscalled barometers can measure the air pressure.Atmospheric air pressure measurements aregiven in hectopascals (hPa). Several times a day,air pressure is read at various weather stationsaround the world. Many observers around Aus-tralia measure air pressure and other aspects ofthe weather and send them to the national andregional centres of the Bureau of Meteorology.These observations are combined with othersmade from satellites, aircraft, ships at sea and inother countries to prepare weather maps.

The main lines that we see on weather mapsare called isobars. Isobars are lines joining placesof equal pressure.

Highs and lowsThe average weight of air at sea level is 1013 hPa.If air pressure measures more than 1013 hPa, it isusually an area of sinking air and is generally anarea of high pressure. High pressure systems areoften called anticyclones. You can see from thetable opposite what a high pressure system lookslike and the anticlockwise direction the air travelsin a high pressure system. The moving air, knownas wind, always moves out of a high and into a lowpressure system.

If air pressure measures below 1013 hPa, it isusually an area of rising air, and is generally anarea of low pressure. Low pressure systems areoften called cyclones. You can see in our table whata low pressure system looks like and the clockwisedirection the air travels in a low pressure system.

Pressure systems generally move from west toeast as they move across Australia and around theworld. As they move they change in shape andoften change their latitudinal position.

PRESSURE SYSTEMS

Sometimes people confuse pressure systems withair masses. An air mass is a large section of theatmosphere containing air with a similar tem-perature and moisture content. A line drawn on aweather map to show where two different airmasses meet is called a front. There are two maintypes of fronts: cold fronts and warm fronts.

When we look at the direction of winds on aweather map we can work out if temperatures arewarmer, cooler or about normal for the time ofyear. In Australia, a northerly wind (coming fromthe north) means warmer than normal tempera-tures and a southerly wind, cooler than normaltemperatures. Easterlies and westerlies meantemperatures that are around normal.

AIR MASSES AND FRONTS

WINDS AND TEMPERATURE

SAMPLE STUDYSnowfalls to the south and central ranges of south-eastern AustraliaThe weather map below for 30 July 2003 shows a cold front moving into the Tasman Sea that has brought a cold snap to south-eastern Australia. Cold and moist air from the ocean to the south of Australia moved across Tasmania, Victoria and New South Wales bringing extensive snowfalls to the higher parts of the tablelands and ranges. Over 40 centimetres of snow fell in the Snowy Mountains and there were falls of up to 20 centimetres over the Central Tablelands. While such snowfalls are welcome news for skiers during the winter months, they often create difficult conditionsfor graziers who must take early precautions to protect their sheep from the very cold weather. Weather map, 30 July 2003

HIGH

LOWLOW LOW

1028

1024

1020

1016

1012

10081004

2.6UNDERSTANDINGWEATHER MAPS


35

1. What is another name for a weather map?2. List three differences between a low and a high

pressure system.3. What does a weather map indicate when:

(a) isobars are close together?(b) isobars are well apart?

4. What do we call the lines that are drawn on weather maps to separate different air masses?

5. Observe the weather map below.

(a) Estimate the wind direction in Adelaide. Is it windy or calm?

(b) Identify the pressure systems at A, B and C.(c) Identify the types of fronts at D and E.

AB

E

C

D

1012

1012

1020

1020

1024

1024

1028

1028

1032

1032

1016

1016

1016

(d) Describe the temperatures at Brisbane, Sydney, Melbourne, Adelaide and Perth, using the terms warmer, cooler, about normal for the time of the year.

(e) Name any of these cities in which you think it could be raining and give reasons for your answer.

(f) Which capital city is about to experience a cool change?

6. Observe the sample study.(a) What is the central pressure of the high

pressure system over South Australia?(b) What separates this high and the low further

west to the south of Western Australia?(c) Using your own words, describe the weather

being experienced over south-eastern Australia. Make sure you mention wind strength and direction, cloud cover, precipitation including snowfall and the temperature for this time of the year.

(d) Why did the weather situation bring widespread snowfalls?

7. Go to www.jaconline.com.au/geoactive/geoactive2 and click on the Weather Satellite weblink for this chapter. Select one satellite image and describe the pattern of cloud over Australia.

Worksheets2.4 Watch the weather

TOOLBOXInterpreting synoptic charts

Symbol Name Description Associated weather

Isobars Lines joining places of equal pressure

The closer the isobars are, the stronger the winds.

High pressure system

Area of sinking air Generally fine weather. Winds rotate around these systems in an anticlockwise direction.

Low pressure system

Area of rising air Generally cloudy weather and a good chance of rain. Winds rotate around these systems in a clockwise direction.

Tropical cyclone

Area of rapidly rising air Torrential rain, very strong and destructive winds in a clockwise direction. Given a name (e.g. Tropical Cyclone Pamela)

Cold front

Separates warm and cold air, with the cold air behind the front

Fall in temperature, may bring rain and storms. Front moves in the direction of the arrowheads.

Warm front

Separates warm and cold air, with the warm air behind the front

Increase in temperature; may bring light showers. Uncommon in Australia.

102010181016

10181016

1014

H

100810

101012

L

9981000

1002

T.C. Pamela

GEOactive 2

36

Natural resources are the wealth supplied bynature that is available for human use. Naturalresources include water, soil, forests, fish, energyand mineral deposits, and wildlife and naturalscenery. Australia has a greater value of naturalresources per head of population than any othercountry in the world. The main reason is that wehave a small population in a very large country.The United States and China, for example, are farbetter endowed with natural resources than Aus-tralia, but they have much larger populations.

Australia is rich in energy resources. On theworld energy scene, Australia is: the worlds main exporter of black coal a major uranium exporter a major exporter of liquefied natural gas.

At White Cliffs in far-western New South Wales, solar reflectors have the potential to make a significant contribution to the towns power needs. The installation is already the source of power for the small towns street lights, post office, hospital, school and community centre.

Australia has abundant quantities of bothblack and brown coal with about 8 per cent of theworld total of black coal and about 15 per cent ofthe worlds brown coal. The main black coalfieldsare in the Hunter Valley/Sydney Basin area ofNew South Wales and the Bowen Basin inQueensland. The main brown coalfields arelocated in Victorias La Trobe Valley. AlthoughAustralia has limited supplies of crude oil, vast

ENERGY

supplies of natural gas have been discovered,particularly in the North West Shelf area off thecoast of Western Australia. Australias uraniumresources are among the largest in the world.

Research and development of renewableresources is an important step towards a sus-tainable future. In Australia, there is consider-able potential for the use of renewable energysources, such as solar and wind energy.

Australia is also rich in mineral resources. ThePilbara region in Western Australia has some ofthe largest reserves of iron ore in the world.Large reserves of bauxite and aluminium exist atWeipa in Queensland and the Gove Peninsula inthe Northern Territory. Australia also producesmany other minerals, including silver, copper,nickel and tin. The main goldfields are located inWestern Australia.

Australia is: the worlds largest exporter of iron ore, bauxite,

lead, diamonds, zinc ores and mineral sands the worlds second-largest exporter of alumina the worlds third-largest exporter of gold.

Mount Tom Price is a huge iron ore mine in the Pilbara region in Western Australia. To learn more, go to www.jaconline.com.au/geoactive/geoactive2 and click on the Mining weblink for this chapter.

MINERALS

2.7AUSTRALIAS PATTERNS OF

NATURAL RESOURCES


37

AU STRALIA

Macquarie Island (1997)

Heard Island and McDonald Islands (1997)

N

0 250 500 km

Shark Bay(1991)

Great Barrier Reef(1981)

Fraser Island(1992)

Tasmanian Wilderness(1982)

KakaduNationalPark(1981)

Lord HoweIsland Group

(1982)

(1982)

Central EasternRainforest Reserves

(1986)

Wet Tropics ofQueensland

(1988)

Willandra LakesRegion (1981)

Uluru Kata TjutaNational Park

(1987)

Australian Fossil Mammal Sites(Riversleigh) (1994)

Australian Fossil Mammal Sites(Naracoorte) (1994)

Royal Exhibition Buildingand Carlton Gardens (2004)

Greater BlueMountains Area(2000)

Year of listing

PurnululuNational Park(2003)

Australia has generally poor soils, especially whencompared with those found on other continents,such as North America and Europe. Most Aus-tralian soils are low in nutrients, and in some partsof the continent, particularly the more arid areas,high salt content is also a problem. Most parts ofAustralia are suitable for only sheep and cattlegrazing rather than intensive agriculture, due tothe combination of low rainfall and poor soils.

There are patches of good soil scatteredthroughout the continent. These include soilsformed on rock of volcanic origin, such as those onthe Darling Downs in Queensland and aroundOrange in New South Wales. Alluvial soils arealso found in river valleys, such as those along theClarence River in New South Wales and aroundthe Margaret River in Western Australia.

Australia, with its unique flora and fauna, hasmany places of great natural beauty. The spec-tacular scenery attracts tourists from all over theworld. Several places in Australia are includedon the World Heritage List. This means thatthey are recognised as being of global importancebecause they are places of great natural or cul-tural significance. For example, Kakadu NationalPark is recognised as a World Heritage areabecause of its natural significance (includingexceptional natural beauty and biologicaldiversity) and cultural significance (includingAboriginal rock art and ceremonialsites). Other places of unique naturalscenery are the Great Barrier Reefand the Blue Mountains.

SOILS

NATURAL SCENERY

Apart from Antarctica which has no trees Australia is the worlds least forested continent.The prevailing vegetation in Australia is wood-land and shrubland. Before European settlementonly about nine per cent of Australia was for-ested. Today, about five per cent of the country isforested. Even though Australia exports timberand timber products, large amounts of timber,particularly softwoods, have to be imported.

1. Why is Australia considered to be rich in natural resources?

2. In which natural resources is Australia rich?3. In which natural resources is Australia comparatively

poor?4. Use a blank outline map of Australia as a starting

point to create a poster or PowerPoint presentation about Australias World Heritage sites. Search for information in your library, in magazines or go to www.jaconline.com.au/geoactive/geoactive2 and click on the World Heritage weblink for this chapter.

5. Research one important natural resource.(a) Where is it located?(b) What is the size or amount of the resource?(c) How is it used?(d) Describe the current state or condition of the

resource.

FORESTS

Australias World Heritage sites

GEOactive 2

38

The long geographic isolation of Australia fromother continents has resulted in an exceptionalvariety of plant and animal life. From arid cen-tral Australia to the tropical forests of northQueensland, no other country has such a variety.More than 80 per cent of Australias flora andfauna is found nowhere else in the world. Theestimated number of native and introducedspecies living in Australia about one million is more than twice the number of species inNorth America and Europe combined.

Due to the generally low amounts of rainfall andits unreliability, most of the flora in Australia ischaracterised by drought-resistant qualities. TheAustralian land flora comprise over 12 000 speciesand many of these are endemic to Australia that is, they occur naturally in Australia andnowhere else in the world. For example, most ofAustralias 500 different species of Eucalyptus(gum trees) are endemic. Some plant species arenot only unique to Australia but also unique tosmall areas of Australia. For example, about 75per cent of the flowering trees and shrubs in thesouth-west corner of Australia have been found tobe unique to this area.

Grass trees (Xanthorrhea sp.) are among the many plant species that are endemic they occur naturally only in Australia.

UNIQUE FLORA

The distribution of vegetation in Australia isstrongly influenced by climate. Only about five percent of Australia is forested. Most of this forest veg-etation occurs along the wetter eastern coast andhighlands area. The forests are dominated by euca-lypt trees, which are tough and durable and able towithstand the frequent fires that occur. As rainfalldecreases inland, trees decrease in number andbecome smaller and further apart. Eucalypts arestill the main types of tree found there. Furtherinland, as the climate becomes increasingly dry,grasslands and shrubs begin to dominate.

Most of the worlds marsupials are found inAustralia. They include the bandicoot, koala,kangaroo, wallaby, wombat and the Tasmaniandevil. Marsupials have pouches in which theysuckle and carry their young. Marsupial babiesare born in a tiny immature state and completemuch of their development in the pouch.

Despite the number of unique marsupials inAustralia, most of our native animals are not mar-supials. Most are placentals, which means that theyoung remain in the womb for much longer thanmarsupials and there is no pouch. Australian pla-cental animals include bats and rodents and suchmarine mammals as seals, dugongs and dolphins.

Most mammals reproduce by giving birth to liveyoung. Monotremes are unique in being the onlymammals that lay eggs. There are only threespecies of monotreme in the world: the platypusand two species of echidna. One echidna speciesoccurs in New Guinea but the platypus and theother species of echidna are uniquely Australian.

Loss of species in Australia has been largelycaused by habitat destruction and degradationand this problem is still occurring. Because mostAustralian species are found nowhere else, wehave a special responsibility to conserve them.

There are the same number of species ofreptiles in an average Australian back-yard as there are in the whole of England.

UNIQUE FAUNA

2.8AUSTRALIAS UNIQUE

FLORA AND FAUNA


39

1. Define the following terms: endemic, marsupial, monotreme.

2. What is a major reason for Australias variety of unusual plant and animal life?

3. What is the main characteristic of flora in Australia?4. Account for the distribution of vegetation in

Australia.5. Select two animals and explain how they have

adapted to survive in the desert.6. Use your knowledge of the evolution of the

Australian continent to explain why echidnas are found in New Guinea as well as in Australia.

7. Create a colourful poster, web page or report that explains the adaptations of flora and fauna to the Australian environment.(a) Select two species one animal or plant from

inland areas and one animal or plant from coastal areas.

(b) Use your library or the Internet to research the animals or plants.

(c) Include a sketch and label it to draw attention to the appearance and main characteristics of the animals or plants.

(d) Include a location map and interesting statistics.(e) Write a paragraph describing the habitat and

some of the characteristics that indicate how these animals or plants have adapted to their environments. Include any possible factors that might affect their survival as a species.

To find out more about Australias plants and animals, go to www.jaconline.com.au/geoactive/geoactive2 and click on the Flora and Fauna weblinks for this chapter.

Budgerigars feed on seeds produced by native plants. They are nomads, and in large flocks of a few thousand or more they follow the flowering cycles.

Honey ants store food and water in their abdomen, which swells up like a plastic bubble. When food is scarce, they vomit up the nectar to feed the colony.

The spinifex hoppingmouse does not sweat,its droppings are dry andits urine is very concentrated. A female feeds her young onconcentrated milk and drinks their urine.

Spinifex leaves roll into tight cylinders during the

hot desert day to reduce the surface area exposed

to the sun. Spinifex roots spread deep and wide to

pick up both ground and surface water.

Death adders are commonly found at

night, soaking up the heat from roads. Rock wallabies rest in

shady caves and crevices during the hottest part of the day. When no grasses are available, they can eat leaves, bark and roots.

Bilbies always stay close to one of several burrows they dig. These protect them from desert heat and predators.

South Australias desert spadefoot toad hibernates in burrows for most of the year, coming out to breed and lay eggs only when it rains.

The marsupial mole is blind because it has no need for eyesight when living underground. It moves underground by swimming through the sand.

Mulga have specially shaped leaves and branches that funnel rainfall to the base of the tree.

The camel has a double row of eyelashes on each eye to keep out glare and grit. It stores energy as fat in its hump and can swallow around 100 litres of water at a time.

Termites live in tall mounds of clay. They are protected inside the mound from the hot, dry desert winds.

Life is rather tough in a desert environment. Desert plants and animals face extremes of temperature, food shortages and a lack of readily available water. To survive, they have had to adapt to these harsh conditions.

GEOactive 2

40

The Daintree rainforest is located about two-hoursdrive north of Cairns in Queensland. The northernsection near Cape Tribulation borders the GreatBarrier Reef. The Daintree River flows through thesouthern section. The Daintree is part of the WetTropics World Heritage site, listed in 1988 becauseit satisfied the following four criteria: it shows major changes in the Earths evolution it shows ongoing evolution it has outstanding aesthetic value it is the home of endangered species, for

example, the cassowary.Much of the Daintree is inaccessible wilderness

in the higher areas, but very accessible in the hillsand river flats of the lower eastern parts. It has oneof the wettest and warmest climates in Australia.Over 400 species of trees have been identified inthe Daintree and a substantial number are foundonly within its borders. There are many otherferns, orchids, palms, mosses and lichens.

Over the last 200 years, human activity hasreduced the Daintree rainforest to one-fifth of itsoriginal area. This has resulted in plant andanimal species becoming endangered and extinct.The rainforest has been cleared for logging,mining, farming, roads and tourism.

AUSTRALIA

146E

16SCape Tribulation

Cow Bay

Mossman

Port Douglas

Cairns

Daintree River

DaintreeNationalPark

N

0 25 50 km

WorldHeritage area

DaintreeNational Park

The Daintree National Park is located within the Wet Tropics World Heritage area.

THE DISAPPEARING RAINFOREST

Clearing the rainforest has resulted in: changes to food webs and ecosystems the lower storey receiving more sunlight,

allowing eucalypts to enter the rainforest less leaf litter and therefore fewer nutrients fertilisers from farms running off into the sea,

killing coral the invasion of exotic plants and feral animals more fires.

Some rare animals live in the forest, includingtwo species of tree kangaroos and the Daintreering-tailed possum. The rainforest houses theworlds largest moth and the smallest bat. Thecassowary is endangered, with only about 50 birdsremaining in the Daintree. There are 1.5 millionidentified species of animals in the Daintree. It isestimated there are six million unidentifiedspecies of animals.

Humans have introduced animals into theenvironment, such as cats and pigs, which killnative animals or destroy the native habitat. Thefruit bat has been affected by the introduced paral-ysis tick. Introduced animals also spread diseases.

In the lowland rainforest areas of the Daintree,sometimes referred to as jungle, along the riversand creeks there is a large variety of animalsand plants. Two of the best known are crocodilesand mangroves.

CrocodilesOnly one type of crocodile inhabits coastal north-eastern Queensland: the dangerous estuarinecrocodile. It is the worlds largest crocodile. Thesecrocodiles inhabit the tidal rivers and creeks butcan occur kilometres upstream in fresh water.They take a variety of prey such as crabs, fish,birds, wallabies and domestic dogs, and humanson rare occasions. Larger crocodiles are scaven-gers and can walk several hundred metres fromwater and drag back a dead animal. They arecannibals and eat many smaller crocodiles.

ANIMALS IN THE RAINFOREST

CROCODILES AND MANGROVES

2.9FLORA AND FAUNA OF

THE DAINTREE RAINFOREST


41

Estuarine crocodile in the Daintree

MangrovesMangrove forests are dense communities of plants,consisting of different species of trees, creepers,vines, lichen, algae and sea grasses. They live inthe saline waterlogged soils where conditions fluc-tuate between high and low tide. They form analmost impenetrable maze of root systems alongthe shores of the waterways. Mangrove ecosystemshave important functions in the rainforest: They are vital spawning grounds for fish, crabs

and prawns. They support a large variety of specialist life

forms such as birds, mammals and insects. Flying foxes or fruit bats commonly feed on

blossoms and establish camps. They protect the coastline from strong winds

and erosion. They trap sediments that would otherwise be

washed into the sea, thus protecting manyfragile marine habitats.

The mangroves of the Daintree are an essen-tial part of the habitat of estuarine crocodilesthat feed on the rich sources of food within thewaterways.

1. Why was the Wet Tropics placed on the World Heritage List?

2. Describe the climate of the Daintree.3. List the adverse results of clearing the rainforest.4. Why do estuarine crocodiles thrive in the lowland

forest of the Daintree?5. Explain why mangroves are so important in the

lowland areas.6. Read the story of Old Gummy. Imagine the

government decided estuarine crocodiles were dangerous and should be eliminated. Outline an argument to save Old Gummy.

7. Create a web page with weblinks about endangered Daintree wildlife. To get started, go to www.jaconline.com.au/geoactive/geoactive2 and click on the Daintree weblink for this chapter.

There have been 11 fatal crocodile attacksin Australia in the past 20 years. Croco-diles are unpredictable creatures. The keyto understanding crocodiles is that theyare waters-edge predators and are veryopportunistic. When there are oppor-tunities for prey, they take them.

SAMPLE STUDYOld GummyOld Gummy is an estuarine crocodile that isprobably over sixty years old. He is nearly sixmetres long and weighs close to two tonnes. OldGummy is the dominant crocodile in a stretchof the lower Daintree River. He has a harem ofabout ten female crocodiles with whom hemates. Old Gummy prevents other males frommating with his females by attacking andusually killing them. Like most old crocodileshe bears the scars of many battles. He has lostall of his teeth from encounters when he hascrushed his victims. Once he targets a victim,he swims unseen below the water surface toattack. He explodes upwards from the waterand grabs the animal in his massive jaws. Hethen drags his prey below the water, thrashingand rolling over and over in a death roll todrown the victim. His own offspring are notsafe from attack, and the males are killedbefore they are large enough to be a threat.

GEOactive 2

42

Using area and grid referencesGrid lines running up and down topographic maps (northsouth) are called eastings because the numbers increase the further east they are. Lines running across the map (eastwest) are called northings because the numbers increase the further north they are. When stating location, the eastings are given first, then the northings.

An area reference is a four-figure number that tells us the grid square in which to find a feature. A grid reference is a six-figure number that shows an exact point in the grid square. The third and sixth figures represent one-tenth of the distance between the two grid numbers. However, these divisions are not written on the map, so they must be estimated.

Observe the section of the Rumula map.1. Identify the main form of vegetation in:

(a) AR3566 (b) AR3255 (c) AR3870.2. What is the main form of land use in:

(a) AR3869? (b) AR2569?Can you suggest reasons for this form of land use?

3. What are the main landforms in:(a) AR3365? (b) AR3963? (c) AR2752?

4. Using the terms flat, gentle or steep, describe the gradients in:(a) AR3858 (b) AR3770 (c) AR2159.

5. Locate Lyons Lookout (GR284704).(a) What type of landform is it?(b) What is the altitude of this landform?(c) Describe what you would observe if you stood

on this landform and looked:(i) north (ii) south-west.

6. Identify the main built features at:(a) GR225643 (b) GR241631 (c) GR216551.

7. What is the distance from:(a) GR210604 to 231628?(b) GR222540 to 214570?(c) GR379691 to 356718?(d) What built features would you observe on the

western side of the road as you travelled between the points in:(i) (a)? (ii) (b)? (iii) (c)?

TOOLBOX

The Daintree includes more than one type of rainforest. Here mangrove forest can be seen at the waters edge, with inland lowland rainforest rising behind it.


43Topographic map of the Rumula area of the Daintree

GEOactive 2

44

Use the map opposite to answer the following questions.1. What is the distance from Denham to Monkey

Mia? a. 20 kilometres c. 32 kilometresb. 26 kilometres d. 37 kilometres

2. What is the distance from Denham to Hamelin by road?a. 105 kilometres c. 131 kilometresb. 111 kilometres d. 141 kilometres

3. Wooramel Seagrass Bank is the worlds largest seagrass meadow, stretching 129 kilometres from Gladstone Bay almost toa. Long Point. c. Carnarvon.b. Bush Bay. d. Dubaut Point.

4. In what direction would a boat travel from Carnarvon to Dorre Island?a. West c. North-westb. East d. South-west

Use the photographs and map to answer the following questions.5. What have tourists to the south-eastern tip of Shark

Bay come to see?a. Dugongs c. Dolphinsb. Stromatolites d. Burrowing bettong

6. What have tourists to the eastern shore of the Peron Peninsula come to see?a. Dugongs c. Dolphinsb. Stromatolites d. Burrowing bettong

7. What important habitat is on Bernier and Dorre islands?a. Cliffs c. Sandhillsb. Mountains d. Trees

8. Outline why Bernier and Dorre islands are home to a number of endangered species.

9. Suggest three reasons why Shark Bay was given World Heritage status in 1991 as a unique environment worth preserving.

Broadsheet: Shark Bay

Once common over southern Western Australia, the banded hare-wallaby is now restricted to scrub on Bernier and Dorre islands in Shark Bay. Its decline was mainly due to the spread of farming. The last mainland sighting was in 1906.

The burrowing bettong was once found over most of mainland Australia. The introduction of foxes, rabbits and the use of poison grain have all contributed to its decline. It is now found only on Bernier and Dorre islands in Shark Bay and on Barrow and Boodie islands.

Once abundant in the shrubs and sand ridges of arid Australia, the western barred bandicoot is now found only in the sandhills on Bernier and Dorre islands. It is thought the introduction of feral goats and pigs, rabbits, foxes and cats was responsible for its decline.

The largest population of dugong in the world is found in Shark Bay where they graze on the seagrass.

Stromatolites growing in Hamelin Pool are among the oldest forms of life on Earth.


45

Carnarvon-Gasc

oyne

Jun cti on Ro

ad

Northw

est Coastal

Highw

ay

Usele

ss Lo

op

Road

Tamala

HamelinOverlanderRoadhouse

Carbla

Nanga BayCaravan Park

Carrarang

Useless Loop

Denham

Monkey MiaPeron

Faure

Dirk Hartog

Yaringa

WooramelRoadhouse

Wooramel

Callagiddy

Carnarvon

DisappointmentLoop

Henri Freycinet

Harbour

Hamelin Pool

Gladstone Bay

Herald Loop

Lharidon

Bight

Red Cliff Bay

Hopeless Reach

DisappointmentReach

Faure Flat

Boat Haven Loop

Use

less

Lo

op

Blin

d S

trai

t

South Passage

Freycinet

Reach

Crayfish Bay

Thunder BayBlowholes

False EntranceBlowholes

HeraldHeights

Herald Bay

Louisa Bay

Little Lagoon

Seagrass

Bank

Herald BightLake Montbazin

Broadhurst Bight

Turtle Bay

Naturaliste Channel Wooram

el

Gascoyne

River

Bush Bay

SHARK BAY

Denham

Sound

Big Lagoon

Depuch Loop

Cape Ronsard

Cape CoutureCape Boullanger

Quoin Bluff North

Castle Point

Cape St Cricq

Long PointCape Inscription

Cape Levillain

Quoin Head

Steep Point

Cape Peron North

Guichenault PointHerald Bluff

Cape Lesueur

Quoin Bluff South

Notch Point

Cape BellefinCape Heirisson

Eagle Bluff

Dubaut Point

Petit Point

Goulet Bluff

Garden Point

Giraud Point

Zuytdorp

Cliffs

Flint Cliff

Booldah Well

Yaringa Point

Kopke Point

Faure Island

Pelican Island

Dorre

Island

Bernier

Island

DIRK

HARTOG

ISLAND

+Mount Dorrigo113 m

SaltEvaporationPonds

SaltEvaporationPonds

HEIRISSONPRONG

BELLEFINPRONG

PERON

PENINSULAMiddle Bluff

Zuytdorp Point

SalutationIsland

ProposedAirstrip

26

19

18

14

19

20

15

6

70

9

17

39

27

1

1

Highway

Airstrip

Major road

Track

6Road, Distance in kilometres

0 25 50 km

Weste rnAus t ra l i a

PERTH

to Port Hedland

to Perth

McNeillClaypan

CARRARANGPENINSULA

False Entrance

N

113E 114E

25S

26S

114E113E

26S

25S

Shark Bay, on the west coast of Western Australia

At Monkey Mia, where hand-feeding of dolphins is a popular attraction, tourist numbers increased from 10 000 in 1984 to over 200 000 in 1998.

ContentsChapter 2 PHYSICAL CHARACTERISTICS THAT MAKE AUSTRALIA UNIQUEGlossary2.1 MAJOR LANDFORMS AND DRAINAGE BASINSMAJOR LANDFORM REGIONSSAMPLE STUDYActivitiesRIVERS AND LAKESGEOskills TOOLBOX

2.2 TOPOGRAPHIC MAPSCONTOURSLEGENDAREA AND GRID REFERENCESGEOskills TOOLBOX

2.3 CONTOUR PATTERNSGEOskills TOOLBOX

2.4 UNDERSTANDING LANDFORMS: KATHERINE GORGEGEOskills TOOLBOX

2.5 AUSTRALIA'S PATTERN OF CLIMATE AND VEGETATIONCLIMATE AND RAINFALLPRESSURE SYSTEMSTEMPERATUREAUSTRALIA'S PATTERN OF VEGETATIONActivitiesGEOskills TOOLBOX

2.6 UNDERSTANDING WEATHER MAPSPRESSURE SYSTEMSAIR MASSES AND FRONTSWINDS AND TEMPERATURESAMPLE STUDYGEOskills TOOLBOX

2.7 AUSTRALIA'S PATTERNS OF NATURAL RESOURCESENERGYMINERALSSOILSNATURAL SCENERYFORESTSActivities

2.8 AUSTRALIA'S UNIQUE FLORA AND FAUNAUNIQUE FLORAUNIQUE FAUNAGEOfactsActivities

2.9 FLORA AND FAUNA OF THE DAINTREE RAINFORESTTHE DISAPPEARING RAINFORESTANIMALS IN THE RAINFORESTCROCODILES AND MANGROVESGEOfactsSAMPLE STUDYActivitiesGEOskills TOOLBOX

Broadsheet: Shark BayAnswersIndexBlackline MastersBack to Start

whl: World Heritage List: areas designated as being of global importance for conservation and studyunique: unique: unlike anything else; the only one of its typetect: tectonic: refers to the forces or conditions within the earth that cause movements of the crust such as earthquakes, folds, faults and volcanoesweather: weathering: the breakdown of bare rock by water and temperature changestopo: topography: physical features of an area of land - its height and shaperego: regolith: the layer of broken rock and soil on top of the solid rock of the Earth's crust; also known as mantle rockmass: mass movement: the movement of rock and soil down a slope due to gravitydeposition: deposition: the laying down of material carried by rivers, wind, ice, ocean currents or wavesdrain: drainage basin: the area of land that feeds a river with water or the whole area of land drained by a river and its tributarieserosion: erosion: the wearing away of soil and rock by natural elements such as wind and waterclimate: climate: the long-term variation in the atmosphere, mainly relating to temperature and precipitationdrought: drought: a period of below average precipitationsynoptic: synoptic chart: weather map that uses isobars and other symbols to show the movement of weather systems and patterns of temperature and rainfalliso: isobars: lines drawn on a map joining places of equal barometric pressurerenew: renewable resources: resources that can be replaced in a relatively short amount of time (for example, trees)species: species: a group of plants or animals of the same kind, able to breed with each othermono: monotreme: mammal that lays eggs; the only species are the platypus and echidnamarsup: marsupial: a mammal that keeps and feeds its young in a pouch for a few months after birthendem: endemic: native to a particular area and found nowhere elseeco: ecosystem: a system formed by the interactions of the living organisms (plants, animals and humans) and physical elements of environmentssalin: salinity: the presence of salt on the land surface, in soils or rocks, or dissolved in water in our rivers or ground watermonsoon: monsoon: the seasonal change in wind direction that is experienced in much of the tropics

Textbook Geoactive 2 (chapter2)

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