You may not realize it but the land is changing all the time. The Earth is always working to build new land and to wear down the old. Sometimes changes to the Earth happen rapidly but other changes take millions of years. Let us learn about forces or movements responsible for land formation.

Which forces formed the fold mountains?

 

Land Formation: As we know the Earth is made up of many concentric layers which are divided into three main layers, crust, mantle, and core. The temperature of the Earth�s core is about 4400^oC � 6000^oC but have you wondered why does this heat not reach the surface?

 

The intense heat in the Earth�s interior does not travel to the surface because rocks are a bad conductor of heat. The internal heat of the Earth, therefore, melts the rocks and keeps the asthenosphere in a semi-molten state.

 

Do you know what is asthenosphere?

 

It is the layer underneath the crust and is commonly known as �Mantle�. There are several conditions that cause landform development on the surface of the Earth.

 

But what is a landform?

 

A landform is a natural feature of the Earth�s surface.

Following are the causes of land formation

 

Orogenic or Horizontal movement

 

• The lithosphere or the crust is broken into several small and big plates. These plates float on the semi-molten asthenosphere.
• The horizontal movement of these plates is very slow.
• The plates push, collide or slide past each other. This results in the disturbance in the sedimentary rock deposits lying in between two or more plates.
• The sedimentary rocks are compressed. This compression causes the folding of the rock.
• Almost all the fold mountain ranges of the world have been formed this way. Do you know, what are the forces responsible for the formation of fold mountains?

 

The forces responsible for the formation of fold mountains are called Orogenic movements. The term �orogenic� is derived from the Greek word meaning �mountain-building� and it is named after a Greek mountain, Oros-mountain. These forces act at a tangent to the surface of the Earth and are primarily involved in plate tectonics.

 

Land Formation Questions:

 

1. The layers inside the Earth are divided into how many categories?
a. 1
b. 4
c. 2
d. 3

 

2. The internal heat of the Earth keeps the ___________in a semi-molten state.
a. Lithosphere
b. Centrosphere
c. Stratosphere
d. Asthenosphere

 

3. What type of movement is Orogenic movement?
a. Vertical
b. Upward
c. Diagonal
d. Horizontal

 

4. What is the outcome of compression of sedimentary rock?
a. Melting
b. Breaking
c. Cracking
d. Folding

 

5. Which of the following signifies the meaning of Orogenic?
a. River-building
b. Plains-building
c. Plateau-building
d. Mountain-building

 

Some other types of movements are:

 

Another set of forces operating inside the Earth acts along the radius from the Earth�s center to the surface and are characterized by large-scale uplift or subsidence of land area.

What are these vertical movements called?

 

These vertical movements are called Epeirogenic movements. �Epeiros' is a Greek word that means 'continent �and �genic� or �genetic� means �building�. These movements are caused by the faulting or crack in the Earth�s surface. The products of such movements are block mountains, basins, and rift valleys.

 

Both Orogenic and Epeirogenic are collectively called Diastrophic forces. Do you know why are they called so?

 

The Diastrophic means �originating deep inside the Earth�. Both the forces operate inside the Earth and produce mountains, plateaus, plains, lakes, and big faults. So, which force operates on the surface of the Earth? Exogenic forces operate on the surface of the Earth. Now, let's learn how!

 

Exogenic forces

 

These forces operate on the surface of the Earth. These are the external forces which are also called Destructive forces because they cause widespread destruction through weathering and erosion of existing landforms. They form new landforms through both erosion and deposition.

Land Formation Questions -2

 

1. Which of the following movements are the vertical movements?
a. Diastrophic
b. Exogenic
c. Orogenic
d. Epeirogenic

 

2. Diastrophic means �originating deep inside the __________�.
a. Sea
b. Mountain
c. Plateau
d. Earth

 

3. Which term is used collectively for Orogenic and Epeirogenic?
a. Destructive force
b. Exogenic force
c. Constructive force
d. Diastrophic force

 

4. �Epeiros� is a greek word which means ____________.
a. Land
b. Sky
c. Earth
d. Continent

 

5. Which of the following is not a result of Epeirogenic movements?
a. Block mountains
b. Basins
c. Rift valleys
d. Plains

 

Fill in the Blanks

 

1. Orogenic movement is named after Oros mountain.
2. The temperature of the core ranges from 4400^oC to 6000^oC.
3. Exogenic forces destroy existing landform through weathering and erosion.
4. Diastrophic forces operate inside the Earth�s surface.
5. Orogenic movements act at a tangent to the surface of the Earth

 

True or False

 

1. The asthenosphere is commonly known as the crust. False
2. Orogenic movement is responsible for the formation of the fold mountains. True
3. Exogenic forces operate inside the Earth's surface. False
4. Rocks are bad conductors of heat. True
5. The word 'orogenic' is a Latin word. False�����

 

Read More: Temperature Distribution On Earth: Latitude, Altitude, Currents & Others