Maharashtra Board Class 11 Geography Solution Chapter 6 – Ocean Resources
Balbharati Maharashtra Board Class 11 Geography Solution Chapter 6: Ocean Resources. Marathi or English Medium Students of Class 11 get here Ocean Resources full Exercise Solution.
Std |
Maharashtra Class 11 |
Subject |
Geography |
Chapter |
6 |
Chapter Name |
Ocean Resources |
1) Complete the chain:
A | B | C |
1) Continental Shelf | 1) deeper part | 1) Manganese nodules |
2) Oceanic microorganisms | 2) Abyssal plains | 2) Whales |
3) Oceanic trenches | 3) fishing | 3) Sunda |
4) Vast flat area | 4) plankton | 4) Dogger Bank |
Answer – The completed chain will be as follows : –
A | B | C |
1) Continental Shelf | 1) Fishing | 1) Dagger Bank |
2) Oceanic microorganisms | 2) Plankton | 2) Whales |
3) Oceanic trenches | 3) Deeper part | 3) Sunda |
4) Vast flat area | 4) Abyssal plain | 4) Manganese Nodules |
Q.2) Identify the correct correlation :
A : Assertion; R : Reasoning\
1) A : Continental shelf is a storehouse of mineral oil and natural gas.
R : Continental shelf receives large quantities of load from continental areas.
1) Only A is correct
2) Only R is correct
3) Both A and R are correct and R is the correct explanation of A.
4) Both A and R are correct but R is not the correct explanation of A.
Answer – 4) Both A and R are correct but R is not the correct explanation of A.
2) A: More deposition occurs in the continental slope.
R: The slope is steeper here.
1) Only A is correct
2) Only R is correct
3) Both A and R are correct and R is the correct explanation of A.
4) Both A and R are correct but R is not the correct explanation of A.
Answer – 2) Only R is correct
3) A : The islands are actually peaks of submerged mountains
R : Some peaks of submerged mountains come above the sea level
1) Only A is correct
2) Only R is correct
3) Both A and R are correct and R is the correct explanation of A.
4) Both A and R are correct but R is not the correct explanation of A.
Answer – 3) Both A and R are correct and R is the correct explanation of A.
4) A: The abyssal plains are the deepest parts of the ocean
R: They lie at the bottom of the ocean
1) Only A is correct
2) Only R is correct
3) Both A and R are correct and R is the correct explanation of A.
4) Both A and R are correct but R is not the correct explanation of A.
Answer – 2) Only R is correct
5) A : Sodium chloride and potassium are parts of inorganic oceanic resources.
R : Salt extraction is a major activity in coastal areas.
1) Only A is correct
2) Only R is correct
3) Both A and R are correct and R is the correct explanation of A.
4) Both A and R are correct but R is not the correct explanation of A.
Answer – 4) Both A and R are correct but R is not the correct explanation of A.
Q.3) Give geographical reasons.
1) Fishing has developed in continental shelves.
Answer – That portion of the continent, or part of the land mass of the continent that is submerged under water or borders the coastal areas is known as a continental shelf. The continental shelf is of extreme importance and occupies around 7.6% of the oceanic area. They are often broad, shallow and quite gently-sloping plains covered by water. The continental shelf does not extend uniformly into the ocean as near some coastal areas, it is narrow while in some other parts it may extend for several hundreds of kilometres. For example, they are almost absent or very narrow along the coasts of Chile (in South America), Sumatra (Indonesia) etc. while the Siberian coast near the Arctic Ocean is around 1500 km in width.
Normally, its depth from the sea level is approximately 180 to 200 m. As the sunlight reaches this part of the ocean bed, it is rich in plankton which form a favourite food for fish.
Thus millions of fishes thrive here and the continental shelf has some of the richest fishing grounds in the world, eg, the Grand Banks and Georges Bank in North America. As a matter of fact, fishing in these continental shelves form the backbone of the fisheries industry the world wide.
2) Our knowledge regarding the oceanic trenches is limited.
Answer – Oceanic deeps and trenches – On the oceanic floor, several deep, narrow and steeply sloping depressions are found which are called ocean deeps or ocean trenches. Depending on their depth, the shallow ones are called deeps whereas deeper ones are called trenches. Therefore, it could be said that the oceanic trenches are the deepest parts of the oceans. These trenches could be thousands of metres deep and generally occur along plate boundaries and are often associated with active volcanoes and strong earthquakes. Foe Example the Mariana Trench in the Pacific Ocean is around 11 km deep while the Java trench in Indian Ocean is around 7.7 km deep.
Human knowledge of ocean trenches is limited because of their great depths and there remoteness in access
3) The ocean is a storehouse of minerals.
Answer – The ocean is a storehouse of minerals because of the following reasons –
Continental shelves – Continental shelves are often known to contain the largest source of Oil & Natural gas reserves. Eg Mumbai High in the Arabian Sea. Minerals like diamonds, chromite, magnetite, gold, platinum and phosphorite deposits are also present in mineable quantities in the continental shelf parts of the ocean.
Silica, sand gravel aggregates are often extracted for industrial purposes near the off shore zone.
Common salt or sodium chloride is the most common resource obtained from the oceans, by drying sea water.
Abyssal plain is also known to contain minerals like manganese, iron, nickel and copper
The oceanic floor also contains potassium in large quantities and also at some places, oil and natural gas reserves.
Gypsum deposits are also mined, having formed by evaporation of sea water and formation of Plaster of Paris, used in construction and interior decoration.
4) Like the land, there are landforms below the ocean too.
Answer – There are landforms below the ocean too, just like the land –
Continental shelf – The coastal land or part of the continental edge that gently slopes into the ocean is the continental shelf. These are the gentle slopes or low lying areas eventually getting submerged into the oceans.
Abyssal plains – The oceanic floor consists of extensive flat plains extending several miles called the Abyssal plains. These are just like plains formed on the surface of the earth.
Seamounts and Ridges – Just like Mountains, ranges are landforms that extend for several metres above the sea level on the land, there are seamounts and ridges on the ocean floors. Eg the Mid Indian Ridge. Some of the oceanic ridges are known to have flat tops extensive tops called oceanic plateaus. Eg Chagos Plateau in the Indian Ocean.
Deeps or Trenches – Kuril trench in the Pacific Ocean in Japan are examples of deeps or trenches in oceans which are deep, narrow and steep sloping depression in the oceanic floor much like the V- shaped valleys on the surface of the earth.
Similarly, Canyons and gorges found on the earth’s surface are found on the ocean floor as well.
4) Write short notes on:
1) EEZ
Answer – EEZ stands for Exclusive Economic Zone.
Just like dividing the Earth’s terrain (Continental area) and establish geographic boundaries on land, the oceans have no apparent surface features – just a flat, vast expanse. Therefore, it is apparently difficult to divide, and so ultimately, previously we all used to own the oceans. When ships were first developed they could carry humans and even cargo across the globe. Previously, the governments of all countries agreed that no one owned the oceans. This informal agreement was referred to as the Law of the Sea.
However, the modern foundation of ownership of the Oceans is by the United Nations Convention on the Law of the Sea (UNCLOS 1982). This law says that a country may claim an area extending 12 nautical miles from its coast as its own territorial sea. Additionally this country can exploit 200 nautical miles of the water beyond its coast as its exclusive economic zone EEZ. Ie. the resources, minerals etc. found there can be exploited by that country alone.
International Resources : There are international institutions which regulate the ocean resources. The oceanic resources beyond 200 nautical miles of the Exclusive Economic Zone belong to open ocean and no individual country has the right to utilise these without the concurrence of these international institutions.
India has got the exclusive rights to mine manganese nodules from the bed of the Indian Ocean from that area which lies beyond the exclusive economic zone.
2) Oceanic tourism
Answer – Over the years, ocean tourism has developed immensely in several countries with coastal areas. Ocean tourism may be in the form of cruises, scuba-diving, fishing, beach tourism, etc. Such activities are becoming increasingly popular. Massive new tourist development hubs have been built in many areas, which may include resorts and marinas.
However, on one side though economically these activities are proving to be beneficial and providing livelihood to the people around, on the other hand, due to the adverse affects, it is spoiling the ocean habitats, the flora, fauna and polluting the environment immensely as such.
It has even been estimated that by mid 21st century, many countries may face a problem of food security. Besides food, there may be scarcity of other resources of minerals, drinking water, mineral oil etc. These resources are largely available in oceans rather than on land where they are available in minor quantities that too in specific areas. Therefore, it would be right to say that our future on the earth may depend on our knowledge of the oceans and the way we utilise our wisdom to exploit it for our benefit, in an increasingly over crowded world.
3) Abundance of minerals in oceans
Answer – There is an abundance of minerals in oceans, to the best of our knowledge because –
Continental shelves – The Continental shelves are often known to contain the largest source of Oil & Natural gas reserves. Eg Mumbai High in the Arabian Sea. Minerals like diamonds, chromite, magnetite, gold, platinum and phosphorite deposits are also present in mineable quantities in the continental shelf parts of the ocean.
Silica, sand gravel aggregates are often extracted for industrial purposes near the off shore zone. Silica, as we know is used to making semiconductor chips and microprocessors for computers and cell phones.
Common salt or sodium chloride is the most common resource obtained from the oceans, by drying sea water.
Abyssal plain is also known to contain minerals like manganese, iron, nickel, copper and cobalt.
The oceanic floor also contains potassium in large quantities and also at some places, oil and natural gas reserves.
Gypsum deposits are also mined, having formed by evaporation of sea water and formation of Plaster of Paris, used in construction and interior decoration.
4) Deposition and continental slope
Answer – As we move further into the sea, after the continental shelf is over, there is a sharp decline observed in the depth of the ocean floor. The steepness of the slope in this region can vary between 2° to 5° and this is part is known as the Continental Slope.
The depth of this slope seems to extend from around 200 m to 4000 meters below the sea level. Due to this gradient of steepness, the continental slope stretches over a limited area only and therefore, the deposition of sediments is also limited in this part. It could further be said that, the continental slopes are considered as boundaries of continents. It is said to cover about 8.5 percent of total ocean area. Methane hydrate, a chemical compound formed from the reaction of methane with water, is present on the continental slopes. e.g. The Krishna-Godavari offshore basin covering an area of 1400 sq km, is rich in methane hydrate. On the Continental slope, many traces of submarine landslide activity can be found, like ocean canyons and huge avalanche fans. For example, Congo Canyon is a submarine canyon found near Africa.
5) Answer in detail:
1) The marine pollution is ultimately going to be harmful to the man himself. Discuss.
Answer –Importance of the ocean to humans is increasing by his understanding it as a reservoir of resources like various minerals, oil, natural gas and therefore his dependence on oceans is also likely to increase manifold in the days to come. However, the oceanic waters are getting polluted on a large scale, due to increasing economic activities of the humans, thereby causing a deterioration of the natural quality of the ocean water. Further, the leakages of oil from oil transporting ships, drilling of oil in the coastal basins, disposal of solid wastes containing radioactive matter, nuclear and atomic tests etc. are causing large scale pollution of the oceanic waters. The effluents from the chemical factories brought by river discharges, the disposal of waste from coastal cities, the waste from industries and other factors are polluting the oceanic waters. As a result, the very existence of marine life both flora and fauna is being threatened.
Plastic bags have been found at the bottom of the Pacific Ocean, the world’s deepest point – The Marina Trench . The plastic bag was made 30 years ago. This has highlighted the extent of pollution our oceans have gone through.
Numerous international teams are working around the world but a lot has to be done in order to save humans from mass extinction and the sooner the better.
2) There is similarity in the relief on the land surface and the ocean bottom.
Answer -There is similarity in the relief on the land surface and the ocean bottom –
Continental shelf – The coastal land or part of the continental edge that gently slopes into the ocean is the continental shelf. These are the gentle slopes or low lying areas eventually getting submerged into the oceans. They are just like low lying areas with gentle slopes on the land.
Abyssal plains – The oceanic floor consists of extensive flat plains extending several miles called the Abyssal plains. These are just like plains formed on the surface of the earth.
Seamounts and Ridges – Just like Mountains, ranges are landforms that extend for several metres above the sea level on the land, there are seamounts and ridges on the ocean floors. Eg the Mid Indian Ridge. Some of the oceanic ridges are known to have flat tops extensive tops called oceanic plateaus. Eg Chagos Plateau in the Indian Ocean.
Deeps or Trenches – Kuril trench in the Pacific Ocean in Japan are examples of deeps or trenches in oceans which are deep, narrow and steep sloping depression in the oceanic floor much like the V- shaped valleys on the surface of the earth.
Similarly, Canyons and gorges found on the earth’s surface are found on the ocean floor as well
3) Discuss how development of oceanic tourism should be carried out without disturbing marine life.
Answer – Oceanic tourism has been developed by many countries as an important economic activity with an aim to attract tourists and this has played some role in the recent times for elevating the GDP of several countries with long coastlines.
However oceanic tourism has also been associated with mass pollution of the oceanic waters which could be prevented if practiced with care, without disturbing marine life. Preventing pollution is the best way to minimise it. Some important steps that could be taken are –
There are existing laws by the governments of individual countries to help protect beaches, marine flora and fauna, reduce debris from the cruises or ships, and take steps to regulate marine dumping. However, these laws need to be made stricter with tough penalties, since they do have loopholes as they have not been able to prevent the pollution as per the current scenario and suitable regulating bodies must be appointed for implementing such laws.
Renewable energy sources like wind and solar power should be used for off shore drilling of oil, natural gas and minerals.
Waste water treatment plants should be set up in plenty to prevent industrial wastes, sewerage and other polluted water from being drained directly into the rivers, since eventually all rivers make their way into the oceans.
Encourage organic farming, use of manures and natural insecticides, pesticides like neem water etc instead of chemical fertilisers and insecticides so that the ground water and river waters do not get polluted.
Sewage treatment plants and proper waste management techniques in an eco friendly manner to recycle wastes into usable carbon, nitrogen or phosphorous
compounds which could be used as fertilisers in agriculture and also prevent pollution of our rivers.
Main aim of most of the above points is to minimise spillage of polluting chemicals and other harmful ingredients into the oceans whether through the rivers or through sewerage or canals etc.
6) Show the following on the map of the World:
1) Chagos Range
2) Mariana Trench
3) Dogger Bank
4) Mumbai High
5) Sunda Deep
6) Grand Banks
Also See: Global Climate Change Chapter 5 Solution