Page 114 - Social Studies 7

Lesson Topography of the Earth and Its
5.2

Changes

The coldest spot of the Earth is Antartica's Vostok
FACTS station that recorded a bone chilling -89.2°C
to Understand

The surface of the earth is irregular or uneven. There are various shapes and
forms, many features of land i.e. plains, hills, mountains, plateaus, valleys, tars,
basins, peaks, passes, gorge, basin, desert, sea, oceans, etc. The description of
such uneven or irregular feature of land is called topography. The shape and
structure of the earth's surface due to variation in elevation of the ground is called
the relief features.

There are mainly two types of agents which bring changes on the surface of
the earth and forms different type of relief features. The internal elements like
earthquake, volcano and tsunami, etc. can change the earth's surface suddenly.
Changes bring by external agent is very slow but continuous. Millions of years
ago there was a big sea called Tethys, on the same place where the mountains lie
today. The elements or agents that bring changes on the earth's surface are given
below:
Elements

External Elements Internal Element

1. Sun 1. Earthquake

2. Wind 2. Volcano
3. Rain 3. Tsunami

4. River 4. Underground water
5. Frost

6. Plants and animals
7. Temperature (heat/cold)

Dynamic Social Studies and Population Education - Book VII 114