NMMS Unit 2: Landforms (7th Standard Geography Term -1)
Here is the detailed summary and study notes for Unit 2: Landforms (7th Standard Geography), tailored for NMMS and TNPSC exam preparation.
Comprehensive Notes: Landforms
1. Introduction to Earth Processes
The Earth's surface is constantly changing due to two main processes:
Endogenic Processes (Internal): These originate from inside the Earth and lead to the upliftment and sinking of the Earth's surface.
Exogenic Processes (External): These originate on the surface and involve the continuous wearing down and rebuilding of the land.
Gradation: The process of levelling highlands through erosion and filling up lowlands through deposition.
Weathering: The breaking and falling apart of rocks into small pieces.
Erosion: The wearing down of the landscape by agents like water, wind, ice, and sea waves.
2. Landforms Created by Rivers (Running Water)
A river is water flowing from a source to a mouth along a definite course.
Source: The place where a river originates (usually a mountain/hill).
River Mouth: The place where a river joins a lake, sea, or ocean.
Tributary: A small stream/river that joins the main river.
Distributary: A stream that branches off away from the main river (usually near the mouth).
A. Erosional Landforms of Rivers:
'V' Shaped Valley: Formed by the erosion of mountainous tracks by running water.
Waterfall: Formed when a river falls over a vertical step or when soft rocks are eroded faster than hard rocks.
Plunge Pool: A hollow feature formed at the base of a waterfall by cavitation.
Important Waterfalls:
Highest in the World: Angel Falls (Venezuela, South America).
North America: Niagara Falls (Border of Canada and USA).
Africa: Victoria Falls (Border of Zambia and Zimbabwe).
Tamil Nadu: Courtallam Falls (across River Chittar).
B. Depositional Landforms of Rivers:
Alluvial Fan: Deposition of sediment that occurs when a river enters a plain or foothills.
Meanders: Large bends or twists formed by the river twisting and turning in the plains.
Example: Meanders along River Vellar near Sethiyathope (Cuddalore Dist, TN).
Fact: The term comes from the Meander River in Turkey.
Ox-bow Lake: Formed when a meander loop gets cut off from the main river due to continuous erosion and deposition (also called a cut-off lake).
Floodplain: A flat, fertile layer of soil deposited along the river banks during floods.
Levees: The raised banks of the river formed by deposition.
Delta: A triangular-shaped collection of sediments deposited at the river mouth where the river's speed becomes very slow.
Examples: Cauvery Delta, Ganges Delta, Mississippi Delta.
3. Landforms Created by Glaciers
A Glacier is a large body of ice moving slowly down a slope due to gravity.
Continental Glacier: Covers vast areas of a continent (e.g., Antarctica, Greenland).
Mountain/Valley Glacier: A stream of ice flowing along a valley (e.g., Himalayas, Alps).
A. Erosional Landforms of Glaciers:
Cirque: An armchair-shaped depression with steep sides formed by glacial erosion.
Examples: Corrie (Scotland), Kar (Germany).
Tarn Lake: A lake formed when ice melts inside a Cirque.
Arete: A narrow, rocky, steep-sided ridge formed when two adjacent cirques erode towards each other.
'U' Shaped Valley: Formed beneath glaciers, deepened and widened by erosion.
B. Depositional Landforms of Glaciers:
Moraines: Sediments (rocks, sand, silt) carried and deposited by glaciers.
4. Landforms Created by Wind (Deserts)
Wind is the active agent of erosion and deposition in deserts.
A. Erosional Landforms of Wind:
Mushroom Rocks: Rocks with a narrower base and wider top (because wind erodes the lower section more than the upper). Common in deserts.
Inselbergs: Isolated residual hills standing like pillars with rounded tops.
Example: Found in the Kalahari Desert (South Africa).
B. Depositional Landforms of Wind:
Sand Dunes: Hill-like structures formed by the deposition of sand when wind stops blowing.
Barchans: Crescent-shaped sand dunes.
Loess: Fine and light sand carried over long distances and deposited in large areas.
Example: Large Loess deposits in China (sand brought from the Gobi Desert).
5. Coastal Landforms (Sea Waves)
Formed by the erosion and deposition of sea waves.
A. Erosional Landforms of Sea Waves:
Sea Cliffs: Steep rock faces formed when waves dash against rocks.
Sea Caves: Hollows formed on rocks due to cracks widening.
Sea Arches: Formed when sea caves become bigger and only the roof remains.
Sea Stacks: Wall-like features left when the roof of a sea arch breaks/collapses.
B. Depositional Landforms of Sea Waves:
Beaches: Formed by the deposition of sand and gravel along the shore.
Longest Beach: Miami Beach (South Florida, USA).
2nd Longest Beach: Marina Beach (Chennai, India).
Sand Bar: An elongated deposition of sand/mud almost parallel to the coast.
Lagoon: A shallow stretch of water partially or completely separated from the sea.
Examples: Chilika Lake (Odisha), Pulicat Lake (Tamil Nadu/Andhra), Vembanad Lake (Kerala).
30 Multiple Choice Questions (MCQs)
The breaking and falling apart of rocks into small pieces is called:
A) Erosion
B) Weathering
C) Deposition
D) Gradation
The place where a river originates is known as its:
A) Mouth
B) Source
C) Delta
D) Tributary
Which of the following is the world's highest waterfall?
A) Niagara Falls
B) Victoria Falls
C) Angel Falls
D) Jog Falls
Angel Falls is located in which country?
A) USA
B) Canada
C) Zimbabwe
D) Venezuela
Courtallam Falls is located across which river?
A) Kaveri
B) Vaigai
C) Chittar
D) Thamirabarani
The hollow feature formed at the base of a waterfall is called a:
A) Plunge Pool
B) Meander
C) Levee
D) Delta
Large bends or twists formed by rivers in the plains are called:
A) Ox-bow lakes
B) Meanders
C) Levees
D) Canyons
The raised banks of a river are called:
A) Deltas
B) Levees
C) Distributaries
D) Alluvial fans
Which river flows through numerous curves and gave the name 'Meander'?
A) River Nile
B) River Meander (Turkey)
C) River Amazon
D) River Ganges
A triangular shaped deposition at the mouth of a river is called:
A) Estuary
B) Delta
C) Fan
D) Cone
Antarctica and Greenland are examples of:
A) Mountain Glaciers
B) Valley Glaciers
C) Continental Glaciers
D) Ice Shelves
The armchair-shaped depression formed by glacial erosion is called:
A) Cirque
B) Arete
C) Moraine
D) Mushroom rock
A lake formed when ice melts inside a cirque is known as:
A) Ox-bow lake
B) Lagoon
C) Tarn lake
D) Crater lake
Glacial deposits of rocks, sand, and silt are called:
A) Dunes
B) Loess
C) Moraines
D) Deltas
Mushroom rocks are commonly found in:
A) River valleys
B) Glaciers
C) Deserts
D) Coastal areas
Inselbergs are found in which desert?
A) Sahara
B) Gobi
C) Kalahari
D) Atacama
Crescent-shaped sand dunes are called:
A) Loess
B) Barchans
C) Stacks
D) Cliffs
Large deposits of Loess found in China are brought from which desert?
A) Sahara
B) Thar
C) Gobi
D) Kalahari
Steep rock faces formed when sea waves dash against them are called:
A) Sea Caves
B) Sea Cliffs
C) Sea Arches
D) Sea Stacks
When the roof of a sea arch breaks, the remaining wall-like feature is called:
A) Sea Stack
B) Sea Cave
C) Sea Stump
D) Cliff
Which is the longest beach in the world?
A) Marina Beach
B) Miami Beach
C) Cox's Bazar
D) Gold Coast
Marina Beach in Chennai is the ______ longest beach in the world.
A) First
B) Second
C) Third
D) Fourth
Chilika Lake is an example of a:
A) Ox-bow lake
B) Glacial lake
C) Lagoon
D) Crater lake
Vembanad Lake is located in:
A) Tamil Nadu
B) Odisha
C) Kerala
D) Andhra Pradesh
The stream that branches off and flows away from the main river is called:
A) Tributary
B) Distributary
C) Delta
D) Canal
Which valley shape is associated with Glaciers?
A) 'V' Shaped
B) 'U' Shaped
C) 'I' Shaped
D) 'L' Shaped
"Corrie" is a name for a Cirque in which country?
A) Germany
B) Scotland
C) France
D) USA
Victoria Falls is located on the border of Zambia and:
A) South Africa
B) Kenya
C) Zimbabwe
D) Congo
The wearing down of the landscape by different agents is called:
A) Weathering
B) Erosion
C) Deposition
D) Transportation
Which of the following is NOT an erosional feature of sea waves?
A) Sea Cliff
B) Sea Cave
C) Sea Stack
D) Beach
Answer Key
B | 2. B | 3. C | 4. D | 5. C
A | 7. B | 8. B | 9. B | 10. B
C | 12. A | 13. C | 14. C | 15. C
C | 17. B | 18. C | 19. B | 20. A
B | 22. B | 23. C | 24. C | 25. B
B | 27. B | 28. C | 29. B | 30. D