Advertisements
Advertisements
प्रश्न
Give reasons for the following:
Earth as a whole does not expand.
उत्तर १
About six important Convection Current Cells with over-riding six large plates have been identified below the Lithosphere. The Mid-Oceanic ridges from edges of the plates. For example, the Mid-Atlantic ridge is such a ridge. The molten matter from below adds new crust along such’ ridges. Taking the earth as a whole it has resulted in the spreading of the ocean floor at the rate of 1 cm to about 10 cm every year. It is called the constructive plate movement. At the same time, the crust at the other edges of the plates in oceanic trenches gets destroyed. It is called the destructive plate movement Consequently a balance exists and the Earth as a whole does not expand.
उत्तर २
Inspite of various changes occurring within the earth it does not expand as it is affected by the centripital force of gravity working towards the centre of the earth
संबंधित प्रश्न
What do you understand by ‘Vulcanism’?
What are ‘Volcanoes’?
Distinguish between the following pair of terms associated with vulcanicity:
Cinder Cone and Composite Cone
Match the items given in Column A with the correct ones in Column B.
| Column A | Column B |
| 1. A Rift valley lake | (a) Deccan Trap region of India |
| 2. A horst | (b) Fujiyama |
| 3. A basic lava sheet | (c) Tanganyika |
| 4. Composite cones | (d) Black forest plateau |
| 5. An active volcano | (e) Corndon Hill |
| 6. A Batholith | (f) The Alps |
| 7. A Phaccolith | (g) Upland of Britain is France |
| 8. A young Fold mountain | (h) Stromboli |
Answer the following:
Some volcanoes develop parasitic cones.
Answer the following:
Hot springs are common in volcanic regions.
Give reasons for the following:
Earth’s movements have modified the Earth’s surface.
Out of the following words write down the four that are connected with volcanic activity.
Karst, crater, drumlin, stalactites, gully, pot holes, ash, basalt, swallow holes, dyke, domes, bluffs.
______ belt is known as the “Ring of Fire”.
The upper part of the earth’s crust ______.
