GEOGRAPHY , CLASS IX- LESSON-1:
Q.1: Give an outline of the distribution of continenets and oceans of the world.
Ans: The surface of the earth is composed of 71% continenets and 29% oceans.
In the continents there are plains, pleateaues, hills, mountains, rivers, valleys, deserts and coastal plains are found. Whereas in the oceans submerged plains, ridges, trenches, coral reels are found.
Q.2: Explain why there has been change over the earth's surface ?
Ans: The surface of the earth is never uniform. The natural factors take time to mark its impact, but they have long time effects. These factors include exogenic factors and endogenic factors.
The modification of the surface of the earth due to exogenic facto is known as changes of the earth's surface.
Q.3: What is meant by exogenic factor ? Mention some exogenic factors .
Ans: The exogenic factors or forces are those natural forces which act upon the earth's surface externally. Tjese factors mainly include sunshine, wind, rain, river glacier and sea waves.
Q.4: Why are earthquake and volvcanic eruptions are called endogenic factors ?
Ans: earthquake and volcanic eruptions are called endogenic factors because these factors operate in the earth's interior as well as inthe ocean bottoms.
Q.5: What do you mean by river basin ? Draw a diagram of river basin .
Ans: A river basin is an area from where the river along with their network of tributories carry water. All rivers along with its tribitories from their own river basin.
Diagram (see book)
Q.6. What is tributory / name two major tributories of the Brahmaputra.
Ans: Tributory is a river or a stream flowig into a large river or lake.
The two major tribitories of the river Brahmaputre are- Dibang and Sobansiri
Q.7: Give an outline of river erosion.
Ans: Erosion means 'wearing out' of the river surface. It is one of the major river activities.When a river flows down from a highland to a lowland, it erodes the basin surface.The erosional works mainly depends upon geological formation of the channel. There is less erosional activity in the plain areas than the highland.
Q.8. What do you mean by lateral erosion of a river?
Ans: River water falling from highland reaches the lowland or plains with a decline of slope towards the plain. The flow of water reduces towards the plain and river channel becomes wider. The river bank erosion in the plain areas is called bank or lateral erosion.
Q.9: What is Ox-bow lake ? Draw diagram to show how it is formed ?
Ans: In certain parts of the plain, the river channel may be highly meandering. Such a course fails to carry huge amount of water during summer. Then the river straightens its course leaving the widening course aside.The cut off part then takes the form of a lake like a horse-shoe.This is called horse-shoe lake.
Diagram (see book)
Q.10: What is floodplain ? Write how it is formed .
Ans: While in the middle and lower curse, sediments are deposited on the bed and the banks of river. Due to this kind of continuous sediment deposition, alluvial plains are dormed on both the banks. Such plains are claaed flood plain.
The flood plains are fertile and suitable for cultivation. Extensive flood plains are there on the banks of the rivers like the Brahmaputra, Ganga, Indus etc.
Q.11; Write how and where sandbars are formed i a river channel?
Ans: The sandbars are formed by the sediments on the river bed. They form both on the sides and the middle of the river bed. They are of various shape and size. During rainy season, speedy water current wipes away them.Again when the river water subsides, the sandbars are visible.
Q.12: How are the deltas formed ?
Ans: In the shallow viver or sea side area, small islands take shape looking like assames 'b' (greek -...) These islands are called delta. Ther are found in the river mouth.
Q.13: Write why the wind action is strong in the desets.?
Ans: Inthe deserts also the wind action passes through three stages- erosion, transportation and deposition. This causes change over them. So the wind action is strong in deserts..
Q.14; What is meant by Deflation ?
Ans: Sand and dust are easily transported from one part to the other . This type of blowing away of sand and dust is called deflation.
Q.15: How are sand dunes formed ?
Ans: Ths sand and dust transported through deflation get deposited in certain places, where surface may be raised gradually to form hills. These hills are called sand dunes.
Q.16: What is 'Inselberg'?
Ans: The german term 'inselberg' means isolated island mountain. In fact, inselberg is formed due to abrasion of the highlands.
Q.17: Define glaciers and state how it differs from a river.
Ans: The extremely cold areas of th earth's surface are under ice cover. Such areas include the polar and the high mountainous part. There are huge amount of ice in such areas. The deposits of ice come down slowly over the surface slope. Such moving ice down the slope's is called glacier.
DIFFERENCE BETWEEEN GLACIER AND RIVER.
GLACIER:
Glacier is ice and snow. It is pre-stage of water and does not depend on rainfall.. Its movement is very slow. Glacier is found mainly in cold countries and continents.
RIVER;
On the other hand river carries water. Its basic source is rainfall. Rivers have channel and depends on climatic condition.Some rivers dry in winter season,whereas some remain full with water whole year.
Q.18: What is moraine ? Draw a diagram to show different types of moraine.
Ans: The glaciers in the mountain carry lot of materials other than ice. Such materials are called moraine.
Moraines are four types:
I) Lateral moraine.
Ii) Ground moraine.
Iii) Medial moraine.
Iv)Terminal moraine.
Generally moraines go through the portion between the steep valley side and the moving ice.
Q.19: Write how the glacier horn is formed ?
Ans: The glacier channels are long with U shaped cross profile. Due to the friction caused by the transported materials, the glacier channels become deep. Several glacier may flow down from some mountain. In such situation, the erosional activities on all sides of the mountain make its peak sharp. Such peaks are called glacial horn.
Q.20: What is coast ?
Ans: