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Landforms and their Evolution – Class 11 Geography notes, important questions and MCQs

NCERT Class 11 Geography, chapter 6. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Landforms are produced by geomorphic agents such as running water, groundwater, glaciers, waves and currents, and wind. Each agent forms erosional and depositional landforms. Running water is the most widespread agent, forming valleys, waterfalls, meanders, floodplains and deltas. Groundwater forms karst features in limestone, glaciers form U-shaped valleys and moraines, waves form cliffs and beaches, and wind forms mushroom rocks and sand dunes.

Running water and groundwater

Erosional landforms of running water include V-shaped valleys, gorges, canyons, potholes, waterfalls and incised meanders; depositional landforms include alluvial fans, floodplains, natural levees, meanders, ox-bow lakes and deltas.
Groundwater dissolves limestone, forming karst topography with sinkholes, caves, stalactites (hanging from the roof), stalagmites (rising from the floor) and pillars.
Rivers pass through youth, maturity and old age stages, each with typical landforms.

Glaciers, waves and wind

Glacial erosion forms cirques, horns, aretes and U-shaped valleys; glacial deposits form moraines, eskers, outwash plains and drumlins.
Waves erode coasts to form cliffs, wave-cut platforms, sea caves, arches and stacks; deposition forms beaches, bars, barriers and spits.
Wind, active in deserts, forms deflation hollows, mushroom rocks (pedestal rocks) and yardangs, and deposits sand dunes such as barchans, seif dunes and loess.

Key terms

Meander: a loop-like bend in a river channel
Ox-bow lake: a lake formed when a meander is cut off from the river
Karst topography: landforms produced by groundwater dissolving limestone
Moraine: a deposit of debris left by a glacier
Barchan: a crescent-shaped sand dune

Important questions with answers

What is the difference between stalactites and stalagmites?2 marks

Stalactites are icicle-like deposits of calcium carbonate that hang from the roof of limestone caves, while stalagmites rise upward from the cave floor. When they join, they form a pillar or column.

How is an ox-bow lake formed?3 marks

On a floodplain, a river forms meanders. Erosion on the outer bank and deposition on the inner bank make the meander loop tighter. During a flood, the river cuts across the narrow neck of the loop and takes a shorter course; the abandoned loop is sealed off by deposits and becomes an ox-bow lake.

Describe the landforms formed by running water.5 marks

Running water is the most important agent shaping landforms in humid regions. In the youthful stage, rivers flow fast on steep slopes and erode vertically, forming deep V-shaped valleys, gorges, canyons, potholes, rapids and waterfalls; plunge pools form at the base of waterfalls. In the mature stage, valleys widen, and rivers develop floodplains and meanders. Lateral erosion and deposition create features such as river terraces and incised or entrenched meanders where the land is uplifted. When rivers leave mountains and enter plains, they deposit material as alluvial fans. On floodplains, rivers deposit sediments during floods, forming natural levees along the banks and point bars on the inside of meanders. Meanders may be cut off to form ox-bow lakes. In the old age stage, rivers flow slowly across broad, flat floodplains with many meanders. Where a river enters a sea or lake, its load is deposited to form a delta, often with distributaries, such as the Ganga–Brahmaputra delta. Thus running water forms both erosional landforms in its upper course and depositional landforms in its lower course.

Quick revision

Running water: V-valleys, waterfalls, meanders, floodplains, deltas.
Groundwater: karst, sinkholes, caves.
Glaciers: cirques, U-valleys, moraines.
Waves: cliffs, stacks, beaches; wind: mushroom rocks, dunes.

Exam tips

Prepare a table of erosional and depositional landforms for each agent.
Remember: stalactites hang from the roof; stalagmites grow up from the floor.

Practice MCQs

A crescent-shaped sand dune is called a
1. barchan
2. seif
3. loess
4. moraine
Show answer
Answer: (a) barchan. Its horns point downwind.
A V-shaped valley is formed mainly by
1. glaciers
2. waves
3. wind
4. running water
Show answer
Answer: (d) running water. Rivers cut down in their youthful stage.
Deposits left by a glacier are called
1. moraines
2. deltas
3. levees
4. dunes
Show answer
Answer: (a) moraines. They may be terminal or lateral.
A lake formed by a cut-off meander is a
1. crater lake
2. ox-bow lake
3. glacial lake
4. lagoon
Show answer
Answer: (b) ox-bow lake. It is common on floodplains.
Karst topography develops in areas of
1. granite
2. limestone
3. basalt
4. sandstone only
Show answer
Answer: (b) limestone. Limestone dissolves in water.
A U-shaped valley is formed by
1. running water
2. glaciers
3. wind
4. groundwater
Show answer
Answer: (b) glaciers. Glaciers erode the valley sides and floor.
Mushroom rocks in deserts are formed mainly because
1. glaciers carve them
2. rivers deposit sand
3. wind abrasion is strongest near the ground
4. waves undercut them
Show answer
Answer: (c) wind abrasion is strongest near the ground. Sand-laden wind wears the lower parts more.
Which pair of a landform and its agent is correct
1. cirque – wind
2. barchan – glacier
3. sea stack – waves
4. ox-bow lake – groundwater
Show answer
Answer: (c) sea stack – waves. Stacks are left as cliffs retreat.

All chapters of Class 11 Geography

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.