The image shows a dromedary camel, easily identified by its single hump. These camels are well-suited to hot, arid environments, as indicated by the dry, sparse landscape in the background. Their adaptations for such climates include the ability to store fat in their hump for energy, conserve water efficiently through their kidneys and nostrils, and tolerate high body temperatures. Their wide feet also prevent them from sinking into the sand, making them effective means of transport in desert regions.
The vegetation visible is minimal and appears to be drought-resistant, further supporting the inference of an arid climate. The ground is dry and uneven, typical of desert or semi-desert terrain. The overall scene suggests a region where water is scarce and only specialized plant and animal life can thrive.
Therefore, the climate experienced in the region shown in the picture is most likely a hot, arid climate, characterized by high temperatures, low rainfall, and sparse vegetation, perfectly suited to the adaptations of the dromedary camel.
DISCUSS
Why are the Eastern Highlands called the Great Dividing Range ?
Ans:
The Eastern Highlands are called the Great Dividing Range primarily because they create a significant watershed. This high ridge effectively separates the direction of river flow across eastern Australia. Rivers east of the range generally flow towards the Pacific Ocean, while those to the west flow inland. This physical barrier acts as a clear division in the continent’s drainage systems.
The eastern slopes, exposed to moisture-bearing winds from the ocean, receive higher rainfall and support more lush vegetation. This difference in climate and vegetation further emphasizes the “dividing” nature of this prominent geographical feature.
THINK AND ANSWER
Why can’t Australia’s exotic flora and fauna be found anyw here else in the world ?
Ans:
Australia’s “exotic” (to the rest of the world) plants and animals are mostly endemic, meaning they evolved and exist only there. This uniqueness stems from Australia’s prolonged geographical isolation after splitting from Gondwana around 135 million years ago. This long separation allowed its flora and fauna to evolve independently, without the influence or competition from species on other continents.
Over millions of years, Australia also developed its own distinct environmental conditions, such as nutrient-poor soils, widespread aridity, and specific fire patterns. These unique pressures favored the survival and adaptation of species with specialized traits not commonly found elsewhere. The early absence of dominant placental mammals also allowed unique marsupials and monotremes to flourish and fill ecological roles different from those on other continents.
Continental drift and subsequent climate changes further shaped Australia’s biodiversity, leading to extinctions and the evolution of new, uniquely Australian forms of life. Essentially, Australia’s long isolation and unique environmental history created a natural evolutionary experiment, resulting in a remarkable collection of plants and animals found nowhere else on Earth.
EXERCISES
EXERCISES
A. Fill in the blanks
Australia is located between latitudes 10°S and 40°S and , between longitudes 114°E and 154°E. So, this Island continent lies wholly in the Southern hemisphere. Australia is the sixth largest country in the world but is the smallest continent. The name Australia comes from the Latin word ‘Australis’ meaning Southern. The official name is the Commonwealth of Australia. Some other popular names are the ‘Land of Migrants’ and the ‘Island Continent’.
B. Choose the correct answer
1. The Great Dividing Range is so called because:
- it divides Australia into two halves
- it is very high
- it acts as a watershed between the rivers flowing to the east and those flowing westwards
Ans : it acts as a watershed between the rivers flowing to the east and those flowing westwards
2. The Lake Eyre Basin is called an area of inland drainage because :
- the area keeps changing
- the rivers flowing in this area have no outlet to the sea
- it is a low-lying lake
Ans : the rivers flowing in this area have no outlet to the sea
C. Answer the following questions in brief
Question 1.
Name the water bodies that surround Australia.
Ans:
Australia’s maritime borders are defined by several major water bodies:
- East: The Pacific Ocean, including both the Coral Sea and the Tasman Sea.
- West and South: The Indian Ocean, which surrounds much of the continent.
In essence, Australia is flanked by the Pacific Ocean to the east and the Indian Ocean to the west and south, with northern seas serving as natural connectors between these expansive waters.
Question 2.
Identify and name the important line of latitude that passes through the middle of Australia.
Ans:
The significant line of latitude that crosses through the central part of Australia is the Tropic of Capricorn.
Question 3.
Why are the Eastern Highlands also called the Great Dividing Range?
Ans:
The Eastern Highlands are also named the Great Dividing Range because they form a significant watershed. This extensive mountain system acts as a natural separator for the primary river systems of the continent.
Conversely, rivers on the western side generally flow inland, often contributing to the extensive Murray-Darling basin or terminating in inland lakes. This physical barrier effectively divides the drainage patterns across eastern Australia.
Furthermore, the range plays a role in shaping the climate, creating a climatic divide. The eastern slopes, exposed to moisture-laden winds from the Pacific Ocean, experience higher levels of orographic rainfall, supporting more abundant vegetation. This contrast in rainfall and plant life further underscores the “dividing” characteristic of this prominent mountain range.
Question 4.
What is an ‘aquifer’?
Ans:
An aquifer is a subsurface layer of permeable rock or loose materials like gravel or sand that can store and transmit groundwater. Imagine it as a natural underground area where water collects and flows through connected spaces within the earth’s structure.
Key features include:
- Permeability: The material has interconnected openings that allow water to pass through.
- Underground Location: Aquifers exist beneath the land surface.
- Water Storage: The porous nature of the aquifer enables it to hold significant amounts of groundwater.
- Water Movement: The connected pathways within the aquifer allow water to move.
Question 5.
What is meant by ‘inland drainage’? Give an example.
Ans:
Inland drainage describes a situation where rivers and streams flow into a contained area within a continent and do not reach the ocean. Instead of flowing to the sea, the water typically evaporates, soaks into the ground, or collects in a salt lake or a dry lake bed (playa).
Example:
Several rivers, such as the Diamantina River and Cooper Creek, flow towards Lake Eyre, a large, shallow salt lake located in the central Australian desert. These rivers do not have an outlet to the ocean. The water they carry either evaporates in the dry climate or accumulates in Lake Eyre, which itself does not drain into the sea. While Lake Eyre can fill up during significant rainfall events, it eventually shrinks again due to evaporation.
Question 6.
Which breed of sheep is mainly reared in Australia ?
Ans:
Australia has a long history of Merino farming, and the breed has been selectively bred over generations to thrive in the Australian climate and produce high-quality wool yields. While other sheep breeds are also raised in Australia for meat and coarser wool, the Merino significantly dominates the sheep population and wool production.
Question 7.
Identify the four main sheep-rearing states of Australia.
Ans:
The four main sheep-rearing states of Australia are:
- New South Wales (NSW): Traditionally the leading sheep-producing state, known for its large Merino flocks.
- Victoria (VIC): While smaller than NSW and WA, Victoria still supports a substantial sheep industry, including both wool and meat breeds.
- South Australia (SA): Another key sheep-producing state, with a focus on Merino sheep adapted to its drier conditions.
D. Answer the following questions in one or two paragraphs
Question 1.
Mention two differences between the rivers that flow down the western and eastern slopes of the Great Dividing Range.
Ans:
Here are two key differences between the rivers that flow down the western and eastern slopes of the Great Dividing Range in Australia:
- Direction of Flow and Destination:
- Eastern Slope Rivers: These rivers are generally shorter and flow eastward directly towards the Pacific Ocean.
- Western Slope Rivers: These rivers tend to be longer and flow westward into the inland drainage systems, such as the Murray-Darling basin, or terminate in inland lakes and depressions; they do not directly reach the ocean.
- Water Volume and Permanence:
- Eastern Slope Rivers: Due to higher rainfall on the eastern slopes from moisture-bearing winds off the Pacific, these rivers tend to have a more consistent flow and are often perennial (flowing year-round).
- Western Slope Rivers: Located in the rain shadow of the Great Dividing Range, these rivers experience lower and more variable rainfall. As a result, they often have a lower water volume and can be intermittent or ephemeral (flowing only seasonally or after significant rainfall).
Question 2.
Explain an artesian basin and an artesian well.
Ans:
An artesian basin is an underground geological formation where a water-bearing layer (aquifer) is trapped and pressurized between impermeable rock or clay layers. Picture a water-filled sponge (the aquifer) squeezed between two slices of non-porous material (impermeable layers). The edges of this formation are typically higher than the center, allowing rainwater to seep into the aquifer at these elevated recharge areas.
An artesian well is a borehole drilled into this pressurized aquifer within an artesian basin. The internal pressure of the confined water forces it to rise up the well, often without the need for a pump. It’s like piercing that pressurized water-filled sponge – the water will naturally rise through the opening. Artesian wells can provide a reliable water source due to the large volume of water stored in the artesian basin and the natural pressure that brings it to the surface.
Question 3.
Why is most of the underground water not suitable for human consumption agriculture?
Ans:
Most of the underground water is not suitable for human consumption or agriculture due to a variety of natural and human-induced contamination issues. While groundwater is often perceived as clean because it’s filtered through layers of soil and rock, this natural filtration doesn’t remove all harmful substances.
Here’s a breakdown of the key reasons:
Natural Contamination:
- Dissolved Minerals: As groundwater travels through rocks and sediments, it can dissolve various minerals. High concentrations of naturally occurring substances like arsenic, fluoride, iron, manganese, and salts can make the water unsafe or unsuitable for drinking and can harm crops. For example, high salinity can impede plant growth.
- Radioactive Elements: In some geological formations, naturally occurring radioactive elements like radon and uranium can leach into the groundwater, posing health risks.
- Pathogens: While soil can filter out many bacteria and viruses, some naturally occurring pathogens can still persist in groundwater, especially in shallow or poorly protected aquifers.
Human-Induced Contamination:
- Industrial Waste: Discharge of untreated or poorly treated industrial wastewater can introduce a wide range of toxic chemicals, heavy metals (like lead, mercury, and chromium), and synthetic organic compounds into groundwater sources. These contaminants can be extremely harmful to human health and the environment.
- Agricultural Runoff: The use of pesticides, herbicides, and fertilizers in agriculture can lead to these chemicals leaching into the groundwater. High levels of nitrates from fertilizers, for instance, can be dangerous, especially for infants.
- Sewage and Septic Systems: Inadequate or failing sewage treatment plants and septic systems can contaminate groundwater with pathogens (bacteria, viruses, parasites), nitrates, and other organic matter, making it unsafe for consumption and potentially polluting agricultural land.
- Landfills and Waste Disposal Sites: Leachate from landfills, containing a complex mixture of chemicals, heavy metals, and organic pollutants, can seep into the underlying groundwater.
- Mining Activities: Mining operations can release heavy metals and acidic drainage into groundwater, contaminating it over large areas.
- Leaks from Storage Tanks and Pipelines: Underground storage tanks (for fuel or chemicals) and pipelines can leak, introducing petroleum hydrocarbons and other hazardous substances into the groundwater.
- Saltwater Intrusion: In coastal areas, excessive pumping of freshwater aquifers can lead to the intrusion of saltwater from the sea, making the water too saline for drinking and most agricultural uses.
Question 4.
How are corals formed?
Ans:
Corals are created by tiny marine animals known as coral polyps. These organisms produce a hard outer layer made of calcium carbonate, which serves as their protective shell.
A key factor in the growth of many reef-building corals is their partnership with microscopic algae called zooxanthellae. These algae live within the coral’s tissues, using sunlight to carry out photosynthesis. This process generates energy that supports the coral’s growth, especially in forming its rigid skeleton.
Coral polyps reproduce by cloning themselves, forming large colonies.The solid remains of earlier polyps form a base on which new ones can grow, enabling the reef to expand over time.
To sum up, coral reefs develop through a long-term cycle where polyps, supported by their algae partners, build and stack calcium carbonate skeletons. This natural process depends heavily on stable environmental conditions, including clean water and suitable temperatures.
Question 5.
Write three interesting points about the Great Barrier Reef.
Ans:
- The World’s Most Extensive Biogenic Structure: Stretching for over 2,300 kilometers along the Queensland coastline of Australia, this colossal coral reef system represents the largest formation on Earth built by living organisms and is visible from space.
- A Center for Ocean Life Diversity: This thriving ecosystem harbors an extraordinary range of marine species, providing habitat for over 1,500 kinds of fish and approximately 400 types of coral. It also supports numerous species of mollusks, sea turtles, sharks, dolphins, and a multitude of other marine creatures. It acts as a vital sanctuary for a vast array of ocean life, with many species found exclusively within its boundaries.
- A Geological History Stretching Back Millions of Years: Parts of the Great Barrier Reef possess a surprisingly ancient history, with formations dating back millions of years. While the present living reef structure began to develop around 20,000 years ago atop the remains of older reefs, the underlying geological structures and ancient coral formations could be up to 20 million years old, illustrating a long and complex history of growth and evolution.
E. Map work
On the outline map of Australia given here, neatly mark and label the following :
- the capital cities of the states
- The narrow stretch of water that separates Tasmania from Australia
- The longest perennial river of Australia
- The ocean that lies west of Australia
- A ridge-like feature made up of coral
- write SHEEP FARMING in an appropriate place on the map where it is practised.
Ans:
F. Picture Study
This is a photograph of Australia’s Great Barrier Reef. Why do you think this reef is Australia’s biggest tourist attraction?
Ans:
because its home for bright coloured tropical fishes and crustaceans that abound in this underwater paradise.
LET’S DO SOMETHING
Question 1.
On an outline map of Australia, mark the boundaries of South Wales-Victoria border different from the other borders ? Find out why.
Ans:
The primary reason for the relatively straight and somewhat arbitrary nature of the NSW-VIC border lies in its historical survey and agreement, rather than being based on significant natural features.
Here’s a more detailed explanation:
- Surveyed Line of Latitude: The majority of the border between New South Wales and Victoria follows a line of latitude, specifically the 36th parallel south. This was determined through surveying efforts in the mid-19th century. Surveyors were tasked with establishing a clear boundary between the two rapidly growing colonies.
- Lack of Prominent Natural Boundaries: Unlike some other state borders in Australia that follow rivers, mountain ranges, or coastlines (which are natural and easily identifiable features), a significant portion of the NSW-VIC border doesn’t adhere to such geographical landmarks. While some smaller sections might follow creeks or minor features, the dominant characteristic is its straight, latitudinal alignment.
- Agreement and Practicality: Establishing a border along a line of latitude was a practical solution for clearly demarcating the territories of the two colonies at the time. It provided a relatively straightforward way to define jurisdiction for land ownership, administration, and other purposes. While not based on natural divisions, it was a result of agreement and the surveying technology available.
- Contrast with Other Borders: Many other Australian state and territory borders do utilize natural features. For example:
- The border between Queensland and New South Wales follows the Macintyre River and a range of hills for a significant stretch.
- The border between South Australia and Victoria has a long straight section but also uses the Murray River as part of its boundary.
- The border between Western Australia and South Australia is largely a straight line but also incorporates some topographical features.
Question 2.
Collect information about the Great Barrier Reef from encyclopaedias or the Internet and write a diary describing all you have learnt about it in your scrapbook.
Ans:
My Great Barrier Reef Insights!
Date: August 5th, 2025
Today’s exploration was a deep dive into the wonders of the Great Barrier Reef, using encyclopaedias and online resources as my guides. The discoveries I made were truly captivating, and I’m dedicating a special section in my scrapbook to these amazing facts.
Firstly, the sheer scale of this natural marvel is breathtaking. Extending over 2,300 kilometers along the Queensland coast of Australia, it’s not a solitary reef but a sprawling, interconnected system of nearly 3,000 individual reefs and numerous islands. This makes it the world’s most extensive structure built by living organisms, a monumental creation formed by countless minute coral polyps secreting their calcium carbonate frameworks. Its vastness is so significant that it can even be observed from space, a testament to the collective power of these tiny architects.
Beyond its impressive size, the reef is a thriving center of biodiversity. It’s akin to an underwater treasure chest brimming with life. I found that it shelters over 1,500 varieties of fish – showcasing a spectrum of colours and patterns. The corals themselves exhibit remarkable diversity, with more than 400 distinct species, each contributing to the reef’s intricate architecture and vibrant hues. In addition to fish and coral, the reef provides habitat for a multitude of other fascinating creatures: graceful sea turtles, playful dolphins, migrating whales, and a rich array of sponges and molluscs. Notably, many of these species are endemic, existing nowhere else on Earth, underscoring the reef’s crucial role in global marine conservation efforts.
Finally, I investigated the temporal depth of this natural wonder. While the current living reef began to develop approximately 20,000 years ago upon the remnants of older reefs, the underlying geological formations and ancient coral structures tell a story stretching back millions of years – with some estimations reaching 20 million! This immense timescale highlights a long history of growth and transformation. It’s a landscape profoundly interwoven with their cultural heritage, spiritual beliefs, and traditional practices.
