Landforms and their evolution

Introduction

• The Earth’s surface undergoes continuous changes due to geomorphic processes, which result in different landforms.
• Landforms: Natural features on the Earth’s surface, shaped over time.
• Two Types of Geomorphic Processes:
  1. Endogenic Processes (Internal forces) – Driven by heat from Earth’s interior.
     • Example: Tectonic movements leading to mountain formation (Himalayas, Andes).
  2. Exogenic Processes (External forces) – Driven by external agents like wind, water, ice, and waves.
     • Example: Erosion by rivers creating valleys (Grand Canyon).

Geomorphic Agents and Processes

• Geomorphic Agents: Running water, glaciers, wind, sea waves, and groundwater.
• Processes Involved:
  • Erosion – Removal of surface material by agents like rivers, glaciers, wind.
    • Example: River erosion carving out the Grand Canyon, USA.
  • Transportation – Movement of eroded material by natural forces.
    • Example: Sediment carried by the Ganga River.
  • Deposition – Accumulation of eroded material in new locations.
    • Example: Formation of the Sundarbans delta.

Fluvial Landforms (Landforms by Running Water – Rivers)

Erosional Landforms by Rivers

1. V-Shaped Valleys:
   • Formed due to vertical erosion in youthful river stages.
   • Example: Indus River Valley in Ladakh.
2. Gorges:
   • Deep, narrow valleys formed by intense downcutting.
   • Example: Kali Gandaki Gorge in Nepal.
3. Canyons:
   • Larger and wider than gorges, with steep sides.
   • Example: Grand Canyon, USA (formed by the Colorado River).
4. Waterfalls:
   • Formed where a river flows over resistant rock layers.
   • Example: Jog Falls, Karnataka (Sharavati River).

Depositional Landforms by Rivers

1. Alluvial Fans:
   • Cone-shaped deposits formed at foothills.
   • Example: Himalayan foothills (where rivers like the Kosi deposit sediments).
2. Floodplains:
   • Flat plains created by seasonal floods depositing silt.
   • Example: Indo-Gangetic Plains.
3. Oxbow Lakes:
   • Crescent-shaped lakes formed by river meandering.
   • Example: Lakes along the Mississippi River, USA.
4. Deltas:
   • Triangular landforms at river mouths due to sediment accumulation.
   • Example: Sundarbans Delta (Ganga-Brahmaputra River System).

Glacial Landforms (Landforms by Moving Ice – Glaciers)

Erosional Landforms by Glaciers

1. Cirques:
   • Bowl-shaped depressions at mountain tops.
   • Example: Cirques in the Alps.
2. U-Shaped Valleys:
   • Glaciers erode valleys into a U-shape with steep sides.
   • Example: Glacier National Park, USA.
3. Horns:
   • Sharp, pyramid-like peaks formed by erosion from multiple glaciers.
   • Example: Matterhorn, Alps.

Depositional Landforms by Glaciers

1. Moraines:
   • Glacial debris (rocks, soil) deposited by melting glaciers.
   • Example: Terminal moraines in the Himalayas.
2. Drumlins:
   • Smooth, egg-shaped hills formed by glacial deposits.
   • Example: Drumlin fields in Canada.
3. Eskers:
   • Sinuous ridges of sand and gravel left by meltwater streams beneath glaciers.
   • Example: Eskers in Scandinavia.

5. Aeolian Landforms (Landforms by Wind – Common in Deserts)

Erosional Landforms by Wind

1. Yardangs:
   • Long, narrow ridges sculpted by wind erosion.
   • Example: Yardangs in the Lut Desert, Iran.
2. Deflation Hollows:
   • Depressions created by wind removing loose material.
   • Example: Qattara Depression, Egypt.

Depositional Landforms by Wind

1. Sand Dunes:
   • Hills of sand deposited by wind movement.
   • Example: Thar Desert (Rajasthan, India).
2. Loess:
   • Fine dust deposits carried by wind over large areas.
   • Example: Loess Plateau, China.

Coastal Landforms (Landforms by Sea Waves – Coastal Areas)

Erosional Landforms by Waves

1. Sea Cliffs:
   • Vertical rock faces formed by wave erosion.
   • Example: White Cliffs of Dover, UK.
2. Wave-Cut Platforms:
   • Flat areas left behind after wave erosion.
   • Example: Wave-cut platforms along the California coast, USA.
3. Sea Arches and Stacks:
   • Erosion forms caves, then arches, which eventually collapse into stacks.
   • Example: Old Harry Rocks, UK.

Depositional Landforms by Waves

1. Beaches:
   • Sandy or pebbly shorelines formed by wave deposition.
   • Example: Marina Beach, Chennai.
2. Bars and Spits:
   • Narrow ridges of sand formed by wave action.
   • Example: Chilika Lake Spit, India.
3. Tombolos:
   • Deposits connecting islands to the mainland.
   • Example: St. Michael’s Mount, UK.

Karst Landforms (Landforms by Groundwater – Common in Limestone Areas)

• Formed due to chemical weathering of limestone (carbonation).

Erosional Karst Landforms

1. Sinkholes:
   • Circular depressions due to limestone dissolution.
   • Example: Great Blue Hole, Belize.
2. Limestone Caves:
   • Underground caves formed by dissolved limestone.
   • Example: Borra Caves, India.

Depositional Karst Landforms

1. Stalactites:
   • Icicle-like formations hanging from cave ceilings.
2. Stalagmites:
   • Pillar-like formations rising from the cave floor.
3. Pillars:
   • Formed when stalactites and stalagmites join.
   • Example: Ajanta & Ellora Caves, India.

8. Significance of Landforms

• Agriculture – Fertile floodplains (e.g., Indo-Gangetic Plains).
• Water Resources – Rivers, lakes (e.g., Himalayas as water sources).
• Natural Hazards – Landslides, floods, earthquakes.
• Tourism – Attraction sites (e.g., Grand Canyon, Alps).

MCQ on Landforms_and_their_evolution

1. Consider the following statements regarding fluvial landforms:

1. A gorge is formed due to rapid downcutting by a river and has steep sides.
2. Meanders are more prominent in the upper course of a river due to high energy levels.
3. Deltas are formed when river sediments get deposited in standing water bodies.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 2 is incorrect as meanders are more prominent in the middle and lower course, not the upper course.)

2. Consider the following statements regarding glacial landforms:

1. A cirque is an amphitheater-shaped depression formed by glacial erosion.
2. Moraines are exclusively formed due to the accumulation of ice, not rock debris.
3. U-shaped valleys are characteristic erosional landforms of glaciated regions.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 2 is incorrect because moraines are formed due to the accumulation of rock debris carried by glaciers, not ice alone.)

3. Consider the following statements regarding wind action in deserts:

1. Yardangs are formed due to differential erosion in desert areas.
2. Sand dunes are formed only in humid coastal regions with strong winds.
3. Deflation hollows are created by the removal of loose material by wind action.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 2 is incorrect as sand dunes are primarily formed in arid and semi-arid regions, not humid coastal regions.)

4. Consider the following statements regarding coastal landforms:

1. Sea stacks are remnants of eroded sea arches.
2. Wave-cut platforms indicate past levels of coastal erosion.
3. Tombolos are sandbars connecting a former island to the mainland.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: C) Only three
(All statements are correct.)

5. Consider the following statements regarding karst landforms:

1. Stalactites grow from the floor of limestone caves, while stalagmites grow from the ceiling.
2. Sinkholes are formed due to the collapse of underground cavities in limestone regions.
3. Karst topography is primarily the result of chemical weathering.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 1 is incorrect as stalactites grow from the ceiling, while stalagmites grow from the floor.)

6. Consider the following statements regarding plateaus:

1. Plateaus are formed only by volcanic activity.
2. The Deccan Plateau is an example of an intermontane plateau.
3. The Colorado Plateau in the USA is an example of a tectonically uplifted plateau.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: A) Only one
(Statement 1 is incorrect as plateaus can also form due to tectonic uplift and erosion. Statement 2 is incorrect as the Deccan Plateau is a lava plateau, not an intermontane plateau.)

7. Consider the following statements regarding mass movements:

1. Soil creep is a rapid form of mass movement occurring in steep mountainous regions.
2. Landslides are triggered by factors like earthquakes, rainfall, and deforestation.
3. Solifluction is a type of slow mass movement common in periglacial regions.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 1 is incorrect as soil creep is a slow mass movement, not a rapid one.)

8. Consider the following statements regarding erosion:

1. Abrasion is an erosional process where moving particles wear away rock surfaces.
2. Hydraulic action is the physical breakdown of rocks due to freeze-thaw weathering.
3. Attrition occurs when sediment particles collide and break into smaller fragments.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 2 is incorrect as hydraulic action is the force of water breaking down rocks, not freeze-thaw weathering.)

9. Consider the following statements regarding depositional landforms:

1. Deltas are formed at river mouths due to sediment deposition.
2. Eskers are elongated ridges of sand and gravel deposited by glacial meltwater.
3. Sand dunes are found only in desert regions.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 3 is incorrect as sand dunes can also be found in coastal regions.)

10. Consider the following statements regarding volcanic landforms:

1. Shield volcanoes have gentle slopes and are formed by low-viscosity lava.
2. Composite volcanoes are formed by alternating layers of lava and ash.
3. Caldera formation occurs due to the collapse of a magma chamber after an eruption.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: C) Only three
(All statements are correct.)

11. Consider the following statements regarding groundwater action in landform development:

1. Groundwater causes erosion by dissolving soluble rocks like limestone.
2. Sinkholes can form suddenly due to subsurface collapse.
3. Permeability of rock layers does not affect groundwater erosion.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 3 is incorrect as the permeability of rock layers significantly affects groundwater erosion.)

12. Consider the following statements regarding tectonic landforms:

1. Fault-block mountains are formed due to the upliftment and tilting of large rock blocks.
2. Rift valleys are formed due to compression forces acting on the crust.
3. The Himalayas were formed due to the collision of the Indian and Eurasian plates.

Which of the above statements is/are correct?
A) Only one
B) Only two
C) Only three
D) None

Answer: B) Only two
(Statement 2 is incorrect as rift valleys are formed due to tensional forces, not compression.)