Landforms of the Earth

Question 1

what are depositional plains?
Explain in detail the 3 types of depositional plains

Answer 1

Depositional plains are those formed by the deposition of various materials brought by different agents of transportation.
There are 3 types -
1. RIVER
These plains are found along rivers like Ganga, Mekong, etc.
They are regarded as the granaries of the world
They are divided into Khadar (new deposits) and bhangar (old deposits)
EX - Northern plains of India, Mississippi plains in USA
2. WIND
Ex - mainly deserts like the Sahara and Thar.
They have irregular surfaces made by dunes and hallows.
3. MARINE
found in coastal regions
In Denmark, we find polders and dyke.
A polder is a piece of land reclaimed from the sea or a lake. and a dyke is when an embankment is placed around the submerged land and the water is drained by canals.

Question 2

What are the 3 types of mountains?

Answer 2

Fold, Residual, block

Question 3

SN on structural plains

Answer 3

Structural plains are formed due to upliftment and submergence of land. These diastrophic forces may cause the upliftment of land from underwater or submergence of land underwater. Great plains of USA were uplifted from underwater. Other examples are Coromandel plains

Question 4

Block mountains
how are they formed
characteristics
examples

Answer 4

1. They are formed due to epeirogenic
   forces
2. • the land in between subsides to form a rift valley or a graben and the land on the sides appears to be raised form the horst mountains.
3. Examples are - Black forest mountains, Vosges in France, Sierra Nevada.

Question 5

SN on fold mountains. How are they formed? Characteristics, examples, etc.

Answer 5

1. They are a result of lateral compressions. Rocks compress along faults or cracks to wrinkle and fold. That’s how they are formed.
2. • the upwards fold is known as the anticline, and the downward fold is known as the syncline.
     - Are greater in length than in width
     - Most fold mountains are found on the edge of continents except the himalayas.
     - Between parallel rangers are intermontane plateaus.
3. Examples are - Andes, Himalayas, Zagros, Rockies, Alps, etc.

Question 6

State 6 importances of landforms.

Answer 6

1. Add to the natural beauty of the earth
2. They are relief features and affect climate, wind, temperature, etc (Himalayas example)
3. They are caused due to diastrophic forces occurring inside the earth. these forces are which bring up minerals and fossil fuels.
4. Some mountains are an abode of snow and ice and give rise to perennial rivers.
5. These landforms are present in oceans and seas as well and give rise to great fishing groups
6. They are home to several species of plants, animals, etc. so landforms also contribute to biodiversity.

Question 7

Define plain

Answer 7

A plain is an extensive area of lowland with a level or gently sloping surface.

Question 8

SN on volcanic plateaus

Answer 8

Volcanic plateaus are formed by continuous volcanic eruptions which slowly build up over time. Ex - Deccan plateau. The colombian plateau has 20 layers of magma suggesting 20 different volcanic eruptions took place.

Question 9

Causes of Lanform development

Answer 9

1. Plate tectonics - The plates push and slide past eachother. This causes folding in the earth’s crust which forms fold mountains. These forces are orogenic forces also known as mountain-building forces.
2. Uplift and submergence - the vertical movement of the earth’s crust are known as epeirogenic movements. They are also known as continent-building forces. They are a result of faults or cracks in the earth’s surface.
   Epeirogenic and Orogenic forces are together called diastrophic forces.
3. Exogenic forces - Exogenic forces like wind, soil erosion, etc occur from the outside of the earth.

Question 10

Residual mountains
what are they?
how are then formed
characteristics
and examples

Answer 10

1. Mountains that are subjected to weathering and erosion and have reduced in height are known as residual mountains.
2. They are formed by the continuous weathering and erosion
3. • exogenic forces like wind and denudation have lowered their height
     - They may also be formed on plateaus
     - They are called mountains of denudation
     - Have low elevation and gentle slopes
4. Examples are - Nilgiri in INDIA, Catskill in USA

Question 11

Define Plateau

Answer 11

A plateau is a area of high ground 500 feet above ground level.

Question 12

SN on intermontane plateau

Answer 12

The plateaus which are surrounded by mountains or hills on all sides. They are formed with fold mountains. Ex - Tibetan Plateau (the world’s highest plateau