Updated NCERT Solutions for Class 11 Geography Chapter 6: Landforms and Their Evolution | Important Questions 2026-27
Welcome, students! Get ready to explore the fascinating world of landforms and how they are shaped. This chapter is a visual treat, explaining how rivers, glaciers, and winds act as nature's sculptors. Mastering these concepts is crucial for your CBSE board exams and provides a strong foundation for competitive exams like NDA and UPSC.
Chapter NameLandforms and Their Evolution
SubjectGeography (Book 1: Fundamentals of Physical Geography)
Class11
BoardCBSE
Important TopicsGeomorphic Agents, Running Water & Fluvial Landforms, Groundwater & Karst Topography, Glacial & Coastal Landforms.
Difficulty LevelModerate (Requires visualization and memorization of terms)
Exam WeightageApproximately 4-6 marks, including short and long-answer questions.
Learning Objectives
After completing this chapter, you will be able to:
- Explain the role of geomorphic agents like running water, groundwater, wind, and glaciers.
- Differentiate between erosional (destructional) and depositional (constructional) landforms.
- Identify and describe various landforms created by rivers, such as V-shaped valleys, meanders, and deltas.
- Understand the unique features of Karst topography formed by groundwater.
- Recognize landforms sculpted by glaciers, like U-shaped valleys and moraines.
- Describe the landforms created by wind (aeolian) and sea waves (coastal).
Key Concepts & Definitions
This chapter is full of important terms. Let’s break them down!
- Geomorphic Agents: Natural elements like running water, wind, glaciers, sea waves, and groundwater that can change the Earth's surface. They are also called agents of erosion and deposition.
- Erosion: The process of wearing away the Earth's surface and transporting the eroded material (like rocks and soil) to another location.
- Deposition: The process where the eroded material is dropped or laid down in a new location when the geomorphic agent loses its energy.
- Peneplain: A low-lying plain with gentle slopes, formed by prolonged river erosion. It represents the final stage of a river's erosional cycle.
- Karst Topography: A unique landscape formed by the action of groundwater on soluble rocks like limestone and dolomite. It is characterized by sinkholes, caves, stalactites, and stalagmites.
- Stalactites: Icicle-like formations of calcium carbonate that hang from the ceilings of caves. (Remember: 'C' for Ceiling).
- Stalagmites: Formations of calcium carbonate that rise from the ground of caves. (Remember: 'G' for Ground).
- Cirque (or Corrie): A deep, bowl-shaped, armchair-like depression found at the head of a glacial valley, created by glacial erosion.
- Moraine: Debris (rocks, sand, and clay) transported and deposited by a glacier. They can be lateral (sides), medial (middle), or terminal (end).
- Meanders: S-shaped bends or loops in a river's course, typically found in the middle and lower course on flat plains.
- Ox-bow Lake: A U-shaped water body formed when a wide meander from a river is cut off, creating a free-standing lake.
- Delta: A fan-shaped depositional landform created at the mouth of a river where it meets a sea or lake, caused by the deposition of sediment.
FULL NCERT SOLUTIONS (UPDATED FOR 2026-27)
Here are the complete and detailed answers to all the questions from your NCERT textbook for Chapter 6.
1. Multiple choice questions.
(i) Which of the following is a landform of river erosion?
(a) Delta
(b) Potholes
(c) Alluvial Fan
(d) Levees
Answer: (b) Potholes
Explanation: Potholes are circular depressions in the rocky beds of rivers, drilled by the grinding action of stones and pebbles rotating in the flowing water. Deltas, alluvial fans, and levees are all depositional landforms created by rivers.
Explanation: Potholes are circular depressions in the rocky beds of rivers, drilled by the grinding action of stones and pebbles rotating in the flowing water. Deltas, alluvial fans, and levees are all depositional landforms created by rivers.
(ii) What is the name of the deep, long, and wide troughs or basins of glaciers?
(a) Potholes
(b) Cirques
(c) Aretes
(d) Gorges
Answer: (b) Cirques
Explanation: Cirques are deep, armchair-shaped basins carved by glaciers at the head of a glacial valley. They are a classic erosional feature of glaciated mountains.
Explanation: Cirques are deep, armchair-shaped basins carved by glaciers at the head of a glacial valley. They are a classic erosional feature of glaciated mountains.
(iii) Which of the following is NOT related to the work of glaciers?
(a) Arete
(b) Moraine
(c) Barkhans
(d) Cirque
Answer: (c) Barkhans (Barchans)
Explanation: Barkhans are crescent-shaped sand dunes formed by the action of wind (aeolian process). Aretes, moraines, and cirques are all landforms associated with glaciers.
Explanation: Barkhans are crescent-shaped sand dunes formed by the action of wind (aeolian process). Aretes, moraines, and cirques are all landforms associated with glaciers.
(iv) Which one of the following features is formed by the depositional work of a glacier?
(a) Cirque
(b) Arete
(c) Moraine
(d) U-shaped valley
Answer: (c) Moraine
Explanation: Moraines are ridges of till (unsorted sediment) that are transported and deposited by a glacier. Cirques, aretes, and U-shaped valleys are all erosional features created by glaciers.
Explanation: Moraines are ridges of till (unsorted sediment) that are transported and deposited by a glacier. Cirques, aretes, and U-shaped valleys are all erosional features created by glaciers.
(v) Karst topography is formed due to the action of:
(a) Glacier
(b) Wind
(c) Sea waves
(d) Groundwater
Answer: (d) Groundwater
Explanation: Karst topography is a unique landscape formed when groundwater dissolves soluble rocks like limestone, creating features like sinkholes, caves, stalactites, and stalagmites.
Explanation: Karst topography is a unique landscape formed when groundwater dissolves soluble rocks like limestone, creating features like sinkholes, caves, stalactites, and stalagmites.
2. Answer the following questions in about 30 words.
(i) What do you mean by a ‘Peneplain’?
Answer: A peneplain is a low-relief plain with gentle, undulating slopes, representing the final stage of landscape evolution by river erosion. It is formed after millions of years of continuous erosion, which wears down highlands and fills up valleys, leaving behind a nearly flat surface close to sea level.
(ii) What are the two basic types of glaciers?
Answer: The two basic types of glaciers are:
1. Continental Glaciers (or Ice Sheets): Vast, thick sheets of ice covering large areas of a continent, like those in Greenland and Antarctica.
2. Valley Glaciers (or Mountain/Alpine Glaciers): Long, narrow glaciers that form in high mountain valleys and flow downwards like rivers of ice.
1. Continental Glaciers (or Ice Sheets): Vast, thick sheets of ice covering large areas of a continent, like those in Greenland and Antarctica.
2. Valley Glaciers (or Mountain/Alpine Glaciers): Long, narrow glaciers that form in high mountain valleys and flow downwards like rivers of ice.
(iii) What is a delta? Name a few major deltas of the world.
Answer: A delta is a fan-shaped depositional landform created at the mouth of a river where it deposits sediment faster than the sea can remove it. They form when a river's velocity decreases upon entering a standing body of water. Major deltas include the Nile Delta, the Mississippi Delta, and the Ganga-Brahmaputra Delta (the world's largest).
(iv) What are stalactites and stalagmites?
Answer: Stalactites and stalagmites are cave formations found in Karst topography.
- Stalactites are icicle-shaped deposits of calcium carbonate that hang from the ceilings of limestone caves.
- Stalagmites are upward-growing mounds of mineral deposits that rise from the floor of a cave, often directly below a stalactite.
3. Answer the following questions in about 150 words.
(i) Describe the erosional and depositional landforms of running water.
Answer: Running water (rivers) is a powerful geomorphic agent that creates distinct erosional and depositional landforms, primarily based on the river's stage (youthful, mature, old).
Erosional Landforms (mainly in the youthful stage):
These are formed when the river has high velocity and energy, typically in mountainous regions.
These are formed when the river's velocity decreases, causing it to drop its sediment load, typically in plains and coastal areas.
Erosional Landforms (mainly in the youthful stage):
These are formed when the river has high velocity and energy, typically in mountainous regions.
- Valleys: In the upper course, rivers perform rapid down-cutting, forming narrow and deep V-shaped valleys, gorges, and canyons.
- Potholes and Plunge Pools: Potholes are circular depressions in the riverbed caused by the abrasion of swirling pebbles. Plunge pools are large, deep holes formed at the base of waterfalls due to the force of falling water.
- Incised or Entrenched Meanders: These are deep, winding meanders cut into hard rock, formed when the landmass uplifts and the river has to maintain its course by cutting downwards.
These are formed when the river's velocity decreases, causing it to drop its sediment load, typically in plains and coastal areas.
- Alluvial Fans: Fan-shaped deposits of sediment formed where a fast-flowing river emerges from a mountain onto a flat plain, causing a sudden drop in velocity.
- Deltas: Large, fan-shaped deposits at the river's mouth where it enters a sea or lake. The Ganga-Brahmaputra Delta is a prime example.
- Floodplains, Natural Levees, and Ox-bow Lakes: In the lower course, the river overflows its banks during floods, depositing fine sediment to create a flat floodplain. Coarser material is deposited along the banks, forming ridges called natural levees. The shifting of meanders can cut off a loop, forming a crescent-shaped ox-bow lake.
(ii) What is Karst topography? Describe its four major landforms.
Answer: Karst topography is a distinctive landscape that develops in regions with soluble rocks like limestone, dolomite, or gypsum. It is primarily formed by the chemical action of groundwater, which dissolves the rock to create a unique set of surface and underground features. The name originates from the Karst region of the Balkan Peninsula.
Four major landforms of Karst topography are:
Four major landforms of Karst topography are:
- Sinkholes (or Doline): These are circular to funnel-shaped depressions on the surface. They are formed either by the slow dissolution of rock from the surface downwards or by the collapse of a cave roof. A landscape dominated by many sinkholes is called a sinkhole plain.
- Caves and Caverns: These are large, underground voids or passages formed by the dissolution of limestone along joints and bedding planes. Water seeps through cracks, enlarging them over thousands of years to form extensive cave networks.
- Stalactites and Stalagmites: These are the most spectacular features inside caves.
- Stalactites are icicle-like formations of calcium carbonate (dripstone) that hang from the cave ceiling. They are formed as water rich in dissolved calcite drips down and evaporates.
- Stalagmites are upward-growing mounds of calcite that form on the cave floor from the dripping water. When a stalactite and a stalagmite meet, they form a pillar or column.
- Lapies (or Karren): This is a highly irregular and rugged surface of exposed limestone, characterized by a network of sharp grooves, ridges, and pinnacles. It is formed by the differential dissolution of the rock by rainwater flowing over its surface.
(iii) Describe the landforms formed by the erosional and depositional action of glaciers.
Answer: Glaciers are massive rivers of ice that drastically reshape landscapes through powerful erosion and deposition.
Erosional Landforms:
Glacial erosion occurs through two main processes: plucking (lifting of rock blocks) and abrasion (grinding and scratching).
As a glacier melts, it drops the load of rock and debris it was carrying. This unsorted sediment is called till.
Erosional Landforms:
Glacial erosion occurs through two main processes: plucking (lifting of rock blocks) and abrasion (grinding and scratching).
- Cirque (Corrie): An armchair-shaped, deep hollow at the head of a mountain valley, formed by glacial plucking and frost shattering. When the ice melts, it often leaves a small lake called a tarn.
- Aretes and Horns: An arete is a sharp, knife-like ridge that forms when two adjacent cirques erode back to back. When several cirques erode the sides of a single mountain, they form a sharp, pyramidal peak called a horn (e.g., the Matterhorn in the Alps).
- U-Shaped Valley (Glacial Trough): Glaciers widen and deepen pre-existing river valleys, transforming them from a V-shape to a characteristic broad-floored, steep-sided U-shaped valley.
As a glacier melts, it drops the load of rock and debris it was carrying. This unsorted sediment is called till.
- Moraines: These are ridges of till deposited by a glacier. They are classified by their position:
- Lateral Moraines: Formed along the sides of the glacier.
- Medial Moraines: Formed where two glaciers merge, combining their lateral moraines.
- Terminal Moraines: A ridge of till deposited at the snout (end) of a glacier, marking its furthest advance.
- Eskers: Long, sinuous (winding) ridges of sand and gravel deposited by meltwater streams flowing in tunnels underneath the glacier.
- Drumlins: Elongated, oval-shaped hills of glacial till that look like an inverted spoon. The blunt end faces the direction from which the ice came.
Extra Important Questions (Board Style)
Multiple Choice Questions (MCQs)
1. A sharp, knife-like ridge formed between two adjacent cirques is called a(n):
(a) Horn
(b) Arete
(c) Drumlin
(d) Esker
Answer: (b) Arete. Difficulty: Easy.
2. Which of the following is an aeolian (wind-related) depositional feature?
(a) Pothole
(b) Sea Arch
(c) Barchan
(d) Moraine
Answer: (c) Barchan. Difficulty: Easy.
3. The transformation of a V-shaped valley into a U-shaped valley is the work of:
(a) Running water
(b) Groundwater
(c) Wind
(d) Glaciers
Answer: (d) Glaciers. Difficulty: Medium.
4. Lapies and Sinkholes are characteristic features of which topography?
(a) Fluvial
(b) Glacial
(c) Coastal
(d) Karst
Answer: (d) Karst. Difficulty: Easy.
5. A crescent-shaped lake formed when a river meander is cut off is known as a(n):
(a) Tarn
(b) Ox-bow lake
(c) Playa lake
(d) Lagoon
Answer: (b) Ox-bow lake. Difficulty: Medium.
Short Answer Questions (SAQs)
6. Differentiate between an Alluvial Fan and a Delta.
Answer: An Alluvial Fan is a fan-shaped deposit of coarse sediment formed at the foot of a mountain where a stream's gradient suddenly decreases. A Delta is a fan-shaped deposit of fine sediment formed at the mouth of a river where it enters a sea or lake. The key difference lies in location and sediment size. Difficulty: Medium.
7. What are Mushroom Rocks (or Gara)? How are they formed?
Answer: Mushroom rocks are mushroom-shaped rock formations found in deserts. They are formed by wind erosion (abrasion), where the wind carrying sand particles erodes the lower part of a rock more effectively than the top. This differential erosion results in a narrow base and a broad top. Difficulty: Medium.
8. Explain the formation of a Sea Cave and a Sea Arch.
Answer: A Sea Cave is formed when waves attack a weak spot in a cliff face, eroding it to form a hollow. When two caves on opposite sides of a headland join, or when a single cave erodes through the headland, the remaining feature is a Sea Arch. Difficulty: Medium.
9. What are natural levees?
Answer: Natural levees are raised banks of coarse sediment formed along the sides of a river channel during floods. When the river overflows, it loses energy and deposits its heaviest material closest to the channel, building up these natural embankments over time. Difficulty: Easy.
10. Define a 'Tarn' and a 'Horn' in the context of glacial landforms.
Answer: A Tarn is a small mountain lake that forms in a cirque basin after the glacier has melted. A Horn is a sharp, pyramid-like peak formed when several cirques erode a mountain from three or more sides, like the Matterhorn in the Swiss Alps. Difficulty: Hard.
Long Answer Questions (LAQs)
11. Explain the three stages of a river's life cycle (Youth, Mature, Old) and describe the dominant landforms associated with each stage.
Answer: The life cycle of a river is divided into three stages:
- Youthful Stage: Occurs in steep, mountainous areas. The river flows swiftly, and vertical erosion (down-cutting) is dominant. Landforms include V-shaped valleys, gorges, canyons, waterfalls, and rapids.
- Mature Stage: Occurs on gentler slopes as the river enters the plains. The river's volume increases, and lateral erosion (sideways cutting) becomes more significant than vertical erosion. The valley widens, and landforms include wider floodplains, meanders, and slip-off slopes.
- Old Stage: Occurs on nearly flat plains near the sea. The river's velocity is very low, and deposition is the dominant process. The river flows in wide meanders across a vast floodplain. Landforms include ox-bow lakes, natural levees, and deltas.
12. What are the major landforms produced by wind erosion and deposition in deserts?
Answer: Wind (aeolian) processes create unique landforms in arid regions.
Erosional Landforms:
Erosional Landforms:
- Pediments and Pediplains: Gently sloping rocky surfaces at the foot of mountains.
- Mushroom Rocks (Gara): Rock pillars with a narrow base and broad top, shaped by sandblasting.
- Deflation Hollows: Depressions created by wind lifting and removing loose sand.
- Yardangs: Elongated ridges of rock aligned with the prevailing wind direction.
- Sand Dunes: Hills of sand deposited by wind. Common types include Barchans (crescent-shaped), Transverse dunes (perpendicular to wind), and Longitudinal dunes (parallel to wind).
- Loess: Extensive deposits of fine, wind-blown silt that can be very fertile.
13. Differentiate between constructive and destructive waves and explain the coastal landforms they create.
Answer:
- Constructive Waves: Have a strong swash (forward movement) and weak backwash (backward movement). They deposit material on the beach, building it up. They create depositional features like beaches, spits, bars, and tombolos.
- Destructive Waves: Have a weak swash and a strong backwash. They erode the coastline and carry material away. They create erosional features like cliffs, wave-cut platforms, sea caves, sea arches, and stacks. The continuous action of these waves shapes the dynamic coastal landscape.
Case-Based / Source-Based Questions
14. Read the paragraph and answer the questions that follow:
In the middle and lower course of a river, lateral erosion becomes more prominent. The river flows over a gentle slope and begins to swing from side to side, forming S-shaped loops called meanders. The outer bank of the meander, where the water flow is fastest, experiences erosion, forming a river cliff. The inner bank, where the flow is slower, experiences deposition, forming a slip-off slope or point bar. Over time, the neck of the meander becomes narrower and is eventually cut through, often during a flood. The river takes a new, straighter course, and the old meander loop is left behind as a crescent-shaped lake.
(i) What is the name given to the S-shaped loops formed by a river?
Answer: Meanders. Difficulty: Easy.
(ii) Why does deposition occur on the inner bank of the meander?
Answer: Deposition occurs on the inner bank because the river's velocity is lower there, causing it to drop its sediment load. Difficulty: Medium.
(iii) What landform is created when the meander loop is cut off from the main river?
Answer: An ox-bow lake. Difficulty: Easy.
15. Read the paragraph and answer the questions that follow:
Limestone terrains subjected to dissolution by groundwater are known as Karst landscapes. A key feature is the formation of underground passages. Water rich in dissolved carbon dioxide acts as a weak carbonic acid, seeping through cracks in the limestone. Over millennia, it dissolves the rock, enlarging the passages into vast networks of caves. Inside these caves, a remarkable process of deposition occurs. As water drips from the ceiling, it evaporates slightly, leaving behind minute deposits of calcite. This process, repeated over centuries, forms structures hanging from the ceiling and rising from the floor.
(i) What is the primary process responsible for the formation of Karst landscapes?
Answer: The dissolution of soluble rocks like limestone by groundwater. Difficulty: Easy.
(ii) Name the structures that hang from the ceiling and rise from the floor of these caves.
Answer: Structures hanging from the ceiling are stalactites, and those rising from the floor are stalagmites. Difficulty: Medium.
(iii) Why is rainwater in these regions able to dissolve limestone?
Answer: Rainwater absorbs carbon dioxide from the atmosphere, forming a weak carbonic acid, which chemically reacts with and dissolves the calcium carbonate in limestone. Difficulty: Hard.
Common Mistakes Students Make
- Confusing Erosion and Weathering: Weathering is the in-situ (in place) breakdown of rocks. Erosion is the breakdown and transport of rocks by agents like water and wind.
- Mixing up Stalactites and Stalagmites: Remember: Stalactites hold tight to the ceiling. Stalagmites might reach the ceiling from the ground.
- Interchanging Erosional and Depositional Landforms: Make two separate columns for each geomorphic agent (river, glacier, etc.) and list their erosional and depositional features. Revise this table daily.
- Not Drawing Diagrams: This is a very visual chapter. Questions on V/U-shaped valleys, meanders, or Karst features are best answered with a simple, well-labelled diagram. Practice them!
- Vague Definitions: Be precise. Instead of saying "a delta is a landform at the end of a river," say "a delta is a fan-shaped depositional landform at the mouth of a river formed by the deposition of sediment."
Exam Preparation Tips
- Mind Maps are Your Best Friend: Create a mind map for each geomorphic agent. For example: Running Water -> Erosional (V-shaped valley, Potholes) & Depositional (Delta, Floodplain, Ox-bow lake).
- Focus on Diagrams: Practice drawing and labelling key diagrams: V-shaped vs. U-shaped valley, Stalactites/Stalagmites, Sea Arch formation, and Barchans.
- Use Flashcards: Write a key term (e.g., 'Moraine') on one side and its definition on the other. This is great for quick revision.
- Differentiate and Compare: Prepare short notes comparing related concepts like Arete vs. Horn, Alluvial Fan vs. Delta, and Peneplain vs. Pediplain.
- Last-Minute Revision: Before the exam, quickly go through the definitions, diagrams, and the summary table of erosional vs. depositional landforms for each agent.
Frequently Asked Questions (FAQs)
Q1: What are the main geomorphic agents discussed in Class 11 Chapter 6?
The main geomorphic agents are running water (fluvial), groundwater, glaciers, wind (aeolian), and waves/currents (coastal). Each agent creates unique erosional and depositional landforms.
Q2: What is the difference between a V-shaped valley and a U-shaped valley?
A V-shaped valley is formed by a river in its youthful stage through vertical erosion, creating steep sides. A U-shaped valley is formed when a glacier moves through a pre-existing V-shaped valley, widening and deepening it into a flat-bottomed, U-shaped trough.
Q3: How are deltas formed at the mouth of a river?
Deltas form when a river carrying a large amount of sediment enters a stationary body of water like a sea or lake. The river's velocity drops suddenly, causing it to deposit its sediment load. Over time, this builds up a fan-shaped landmass called a delta.
Q4: Why is Karst topography not found everywhere?
Karst topography only develops in regions where there are thick layers of soluble rock, primarily limestone, dolomite, or gypsum, and sufficient rainfall to create groundwater that can dissolve these rocks.
Q5: What is the importance of studying landforms and their evolution?
Studying landforms helps us understand the dynamic nature of the Earth's surface. It explains how landscapes are formed, why certain regions are prone to erosion, and how natural resources (like fertile floodplains or groundwater in Karst regions) are distributed. It is a fundamental concept in physical geography.
Conclusion: Chapter 6, "Landforms and Their Evolution," is a cornerstone of physical geography. By understanding the processes of erosion and deposition, you gain insight into the world around you. Remember to revise the key terms, practice drawing diagrams, and solve previous year questions (PYQs). Consistent effort will surely help you master this chapter and score excellent marks in your CBSE Class 11 exams and beyond!