Our Changing Earth

Q1. Fill in the blanks.

                        i.        Mushroom rocks are found in deserts.

                       ii.        Ox bow lakes are found in river valleys.

                      iii.        Glaciers are “rivers” of ice.

                      iv.        The highest waterfall is Angel Falls of Venezuela in South America.

                       v.        Sudden movements in the earth interior are cause due to endogenic forces.

Q2. True/False

                        i.        The molten magma inside the earth moves in a circular manner. True

                       ii.        Beach is an erosional feature of sea waves. False

                      iii.        Moraine is a depositional feature of a glacier. True

                      iv.        Volcano is caused by the sudden movements of the earth. True

                       v.        The strength of the earthquake increases away from the centre. False

                      vi.        Moraine is the depositional feature of a glacier. True

Q3. What are the major agents of erosion?

Ans. Water, wind and ice are the major agents of erosion.

Q4. Define loess?

Ans. When sand is deposited in large areas, it is called loess.

Q5. What is vent?

Ans. The narrow opening of a volcano is called vent.

Q6. What is a seismograph?

Ans. An earthquake is measured with a machine called a seismograph.

Q7. What is the name of the scale used to measure earthquakes?

Ans. The magnitude of the earthquake is measured on the Richter scale.

Q8. Write some examples of coastal landforms?

Ans. Examples of coastal landforms are sea caves, sea arches, stacks and sea cliff.

Q9. Write names of a few rivers of the world that form a delta.

Ans. Ganga-brahmaputra, Zaire, Murray-Darling, Amazon, Nile, Murray-Darling

Q10. What are distributaries?

Ans. The river begins to break up into a number of streams called distributaries.

Q11. Why do the plates move?

Ans. Plates move because of the movement of the molten magma inside the earth.

Q12. How are beaches formed?

Ans. Beaches are formed when the sea waves deposit sediments along the shores.

Q13. What is erosion?

Ans. Erosion is the wearing away of the landscape by different agents like water, wind and ice.

Q14. What are meanders?

Ans. As the river enters the plain it twists and turns forming large bends known as meanders.

Q15. What are Lithospheric plates?

Ans. The lithosphere is broken into a number of plates known as the Lithospheric plates.

Q16. How much do lithospheric plates move in a year?

Ans. Lithospheric plates move around very slowly – just a few millimetres each year.

Q17. What is a volcano?

Ans. A volcano is a vent (opening) in the earth’s crust through which molten material erupts suddenly.

Q18. What are the two processes which wear away the landscape?

Ans. The landscape is being continuously worn away by two processes – weathering and erosion.

Q19. How do glacial moraines form?

Ans. The material carried by the glacier such as rocks big and small, sand and silt gets deposited. These deposits form glacial moraines.