Changing Earth

Extra Questions

Short Answer Type Questions:

What should be done to prepare oneself for an earthquake?

Answer: It is recommended to spread awareness amongst our family and acquaintances so that they face a disaster like earthquake confidently. In case earthquake strikes, we should take shelter under a kitchen counter, table, desk or against an inside corner/wall. We should keep away from areas around chimneys, fire places, windows that shatter including mirror and picture frames.

Write briefly about earth movements.

Answer: The movements of the earth are caused due to endogenic and exogenic forces. The endogenic forces act in the interior of the earth and cause sudden or slow movements. The exogenic forces act on the surface of the earth and lead to different landforms.

Can earthquake be predicted? What are the common earthquake prediction methods used by people?

Answer: Earthquakes cannot be predicted but their impact can definitely be minimized if we are prepared in advance. Some common earthquake prediction methods adopted locally by people is studying animal behavior which includes - fish in the ponds getting agitated and snakes coming to the surface.

How are the major landforms formed?

Answer: Major landforms are formed by erosion and deposition. Wind, water and ice are the agents of erosion and deposition. Water causes waterfall, floodplain, sea arches, sea cliff formation etc. Winds cause sand dunes and mushroom rock formation, whereas ice causes the formation of lakes in mountains and glacial moraines.

Long Answer Type Questions:

Describe the forces that cause earth movements.

Answer: The following are the forces that act on the earth:

  1. Endogenic forces: The term ‘endo’ means inside and ‘genic’ means origin.The forces that are originated in the interior of the earth or, in other words, the forces that act in the interior of the earth are called endogenic forces. They are of two types: Sudden forces and Diastrophic forces.
  2. Exogenic forces: The term ‘exo’ means inside and ‘genic’ means origin. Therefore, exogenic forces are the forces that work on the surface of the earth. These forces are erosional and depositional in nature.

How do sea waves lead to landform formation?

Answer: The erosion and deposition by water in the form of sea waves leads to the formation of coastal landforms. These include; sea caves, sea arches, sea cliff and beaches.

Sea waves continuously strike at the rocks. This leads to cracks. The cracks become larger and wider overtime. Thus hollow like caves are formed on the rocks. They are called sea caves. As these cavities become bigger and bigger, only the roof of the caves remains, hence forming sea arches. The erosion further breaks the roof and only the walls remain. These wall like features are called stacks. Sea cliff is the steep rocky coast rising almost vertically above sea water. The sea waves deposit sediments along the shores forming beaches.

Write a short note on earthquake.

Answer: The vibrations caused on the surface of the earth when the Lithospheric plates move are called earthquakes. These vibrations can travel all around the earth.

The place in the earth where the movement starts is called the focus. It is the origin of the seismic energy. The place on the surface above the focus is called the epicentre. Vibrations travel outwards from the epicentre as waves. The strength of the earthquake decreases away from the epicentre. In other words, the greatest damage is usually closest to the epicentre.

Although earthquakes cannot be predicted, the impact can definitely be minimized if we are prepared in advance.

Describe the role of the river in landform formation.

Answer: The running water of the river erodes the landscape. A waterfall is formed when the river tumbles at steep angle over very hard rocks or down a steep valley side. As the river enters the plain, it twists and turns forming large bends called meanders. Due to continuous erosion and deposition along the sides of the meander, the ends of the meander loop come closer and closer. When this happens, over a course of time, the meander loop cuts off from the river and forms a cut–off lake. Such a lake is also called an ox-bow lake. When the river overflows its banks, the neighbouring areas get flooded. When the river floods, it deposits layers of fine soil and other material called sediments along its banks. This leads to the formation of a floodplain. A floodplain is flat and fertile. The raised banks of the river (due to overflowing) are called levees. When the river approaches the sea, it becomes very slow in its flow and begins to break up into a number of streams called distributaries. The speed of the river water is so less that it starts depositing its load. Each distributary forms its own mouth. A collection of sediments from all the mouths forms a delta.

What are the landforms formed by wind? How are they formed?

Answer: The landforms in the desert formed by wind are:

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