Class 8 Structure of Ocean Floor class 8 geography question anwers.
Class 8 geography chapter 4 Structure of ocean floor question answers – Structure of ocean floor std 8 answers pdf – Structure of ocean floor question answers
Q 1. Choose the correct option:
(a)
Like there are landforms on land, ocean floor also has submerged landforms
because ……
(i) There is land under water
(ii) There are volcanoes under water
(iii) Land is continuous and there is water in deeper parts.
(iv) Though land is continuous, its level is not the same everywhere like that of water.
Ans: Though land is continuous, its level is not the same everywhere like that of water.
(b)
Which part of the ocean floor is most useful to the man ?
(i) Continental shelf
(ii) Continental slope
(iii) Abyssal plains
(iv) Marine deeps
Ans: Continental shelf
(c)
Which one of the following option is related to marine deposits?
(i) Rivers, glaciers, remains of plants and animals
(ii) Volcanic ash, continental shelf, remains of plants and animals
(iii) Volcanic ash, lava, fine particles of soil
(iv) Volcanic ash, remains of plants and animals, abyssal plains
Ans:
Class 8 geography chapter 4 question answers pdf – Geography class 8 question answer pdf – Geography chapter 4 class 8 solution
Q 2. (a) Name the landforms shown in the figure.
Ans:
1)Submerged hills and mountains
2)Mid-oceanic Ridge
3)Abssal plain
4)Marine Trench
5)Continental slope
6)Continental
shelf
(b) Which of these landforms is useful for deep sea research?
Ans:
The
Mid-oceanic submerged hills, and marine trenchers are the most useful landforms
for deep sea research as they are very deep from the sea level.
(c) Which of these are appropriate to be used for the protection of marine borders and naval-base building?
Ans:
The
continental shelf and the continental slopes are appropriate to be used for the
protection of marine borders and naval-base building.
Geography chapter 4 class 8 question answer – Geography chapter 4 question answer Maharashtra board- Class 8 geography question answer solution
Q 3. Give geographical reasons:
(a) The study of ocean floor is useful to man.
Ans:
1)Land submerged below oceanic water is called the ocean floor. The ocean floor relief consists of all submerged landforms.
2)The continental shelf is very important from the point of view of humans. Extensive fishing grounds are found in the continental shelf. 3)Natural gas, mineral oil and various minerals can be obtained by mining the continental shelf.
4)The mid-oceanic submerged hills and marine trenches are geologically the most active areas of the ocean- -bed in the world.
5)There are many active volcanoes here. These areas are also earthquake-prone areas. Earthquakes and volcanic eruptions occurring in the ocean-bed give rise to tsunamis in the nearby coastal areas.
6)The
study of ocean floor is useful to man because it help one to understand ocean
pollution, climate changes, untapped resources like mineral resources, natural
gas, etc.
(b) The continental shelf is a paradise for fishing activity.
Ans:
1)The land near the coast and submerged under the sea is called continental shelf. This is the shallowest part of the ocean bed.
2)As this part is shallow, the sunlight reaches its bed.
3)Algae, plankton, etc. grow here. This is food for fish. Fishes come to eat it.
Therefore,
The continental shelf is a paradise for fishing activity.
(c) Some marine islands are actually the peaks of sea mountains.
Ans:
1)The hills and mountains found on the ocean-bed are called submerged hills and mountains.
2)These hills are hundreds of kilometers wide and thousands of kilometers long.
3)Peaks of some of the submerged hills come above the sea level. They are visible to us as marine islands.
4)Iceland in the Atlantic Ocean, Andaman and Nicobar Islands in the Bay of Bengal are examples.
Thus,
Some marine islands are actually the peaks of sea mountains.
d)The continental slope is considered to be the boundary of continents.
Ans:
1)After the extent of continental shelf is over, the slope of the sea bed becomes steeper. This is called continental slope.
2)The depth of the slope is from 200 m to 3600 metres.
3)The
continental slope is narrow. The lower boundary of continental slope is
considered to be the boundary of continents.
e) The disposal of waste materials in the oceans by man is harmful to the environment.
Ans:
1)Man disposes waste includes sewage, solid waste, radio-active material, waste chemicals, plastics, etc. These wastes prove hazardous to the hydrosphere.
2)These materials are extremely harmful to the marine life and its environment.
Therefore,
the disposal of waste materials in the oceans by man is harmful to the
environment.
Question answer of class 8 geography chapter 4 – Class 8 geography chapter 4 Structure of ocean floor question answers – Structure of ocean floor std 8 answers pdf
Q 4. Observe the map on Pg 27 in ‘Give it a try’ and answer the following questions:
(a) Madagascar and Sri Lanka are related to which landform of the ocean floor?
Ans:
Madagascar and sri lanka are related to Marine Islands.
(b) Near which continent are these land forms located?
Ans: Sri Lanka is located near the continent of
Asia, whereas Madagascar is located near in the continent of Africa.
(c) Which islands in our country are examples of peaks of submerged mountains?
Ans: The Andaman and Nicobar Islands are examples
of peaks of submerged mountains.
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