Question 1:
Why do the plates move?
Answer:
The energy system that causes plates to move is believed to arise from the radioactive elements in the earth’s crust and the upper mantle.
Question 2:
What are exogenic and endogenic forces?
Answer:
Endogenic forces are forces which act in the interior of the earth, e.g., earthquake, volcanoes, etc. The forces which work on the surface of the earth are called as exogenic forces, e.g. work of river, wind, glaciers.
Question 3:
What is erosion?
Answer:
The washing away or the removal of the top soil is known as soil erosion. Wind and water are powerful agents of soil erosion because of their ability to remove soil and transport it.
Question 4:
How are flood plains formed?
Answer:
Flood plains are formed in the middle course of the river. The gradient becomes almost flat, hence, the downward erosion is reduced. More of the river’s energy is directed from side by side.
Question 5:
What are sand dunes?
Answer:
A sand dune is a hill or a mound of sand deposited by the wind. Dunes are common in all sandy regions such as sandy deserts and beaches. A sand dune begins to build where there is an obstruction like a large rock or a bush. Sand is deposited near the obstruction. Once the deposition has started the sand dune grows rapidly.
Question 6:
How are beaches formed?
Answer:
Beaches are formed by the deposition of sand and other materials like gravel and pebbles by waves along the shore.
Question 7:
What are ox bow lakes?
Answer:
An ox bow lake is produced when a meander forms almost a complete circle and the meandering river cuts across the narrow neck of land. When silt is deposited at the entrance to this back-water, an ox bow lake is formed.
Question 8:
Some rocks have a shape of a mushroom.
Answer:
Some rocks have a narrow trunk and a broad umbrella- shaped top. Sand particles are carried along by the wind close to the ground due to which the rock is eroded at the base.
Question 9:
Flood plains are very fertile.
Answer:
Due to regular deposition of a fresh layer of silt, these soils are very fertile. The flood plains due to the fertile alluvial soil and abundance of water for irrigation can support large farming populations.
Question 10:
Sea caves are turned into stacks.
Answer:
Continued erosion of the headland may cause the sea cave to fall in, leaving behind an isolated column known as stacks.
Question 11:
Buildings collapsed due to earthquakes.
Answer:
An earthquake is a shaking of the earth. It is caused by sudden movements in the earth’s crust due to the release of energy. It results in the collapse of structures and widespread human loss.
Question 12:
Find out the names of a few rivers of the world that form a delta.
Answer:
Most of the rivers of the world form deltas. Examples of a few rivers are: Ganga in India, Nile in Egypt, Amazon in Brazil, Huang He in China and Zambezi in Africa
Question 13:
Find out the names of a few rivers of the world that form a delta.
Answer:
Most of the rivers of the world form deltas. Examples of a few rivers are: Ganga in India, Nile in Egypt, Amazon in Brazil, Huang He in China and Zambezi in Africa