Test: Our Changing Earth - UPSC MCQ

• The forces which act in the interior of the earth are called Endogenic forces.
• The forces that work on the surface of the earth are called Exogenic forces.

• Exogenic (a.k.a. exogenetic) refers to external processes and phenomena that occur on or above the surface of the earth.
  Example: Comet and meteoroid impacts, the tidal force of the moon, and the radiation from the sun, Weathering effects, and erosion.
• Running water, wind, snow and waves are agents in exogenous processes, and these agents are also known as “Geomorphic agents”.
• ​Whereas, sudden movements such as volcanos are caused by endogenous force.

Thus, option A is correct.

The place in the crust where the movement starts is called the focus. The place on the surface above the focus is called the epicenter. Vibrations travel outwards from the epicenter as waves. The greatest damage is usually closest to the epicenter and the strength of the earthquake decreases away from the center.

• Sea caves are formed by the erosion and deposition of sea waves.
• When the sea waves hit the rocks over and over again, they create hollow-like caves in the rocks.
• This process happens over a long time, and eventually, these caves are formed along the coastlines.

• When a river forms large bends known as meanders, the ends of the meander loop come closer and closer.
• In due time, the meander loop cuts off from the river and forms a cut-off lake, which is also called an ox-bow lake.
• This happens due to continuous erosion and deposition along the sides of the meander.

- Glaciers carve out deep hollows called Glacier Valleys.
- As glaciers move, they erode the land beneath, creating U-shaped valleys.
- Unlike rivers, which form V-shaped valleys, glaciers' immense weight and slow movement widen and deepen the valley floor.
- This erosion process can also form features like fjords and hanging valleys.
- The term "glacial valley" specifically refers to these distinct geological formations created by glacial activity over time.

The magnitude of an earthquake is measured on the Richter scale, which quantifies the energy released during an earthquake.