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Looking for NCERT Class 11 Geography Fundamentals of Geography Chapter 6 Landforms and their Evolution Notes? You’re in the right place! This blog gives you simple and clear notes that make it easy to understand the key concepts of this chapter. Whether you’re preparing for your exams or just want a quick revision, these notes will help you grasp the essential ideas without going through the entire textbook. Let’s dive in!
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Explore Notes of Class 11 Fundamentals of Geography
Introduction
The Earth’s surface is constantly changing due to natural forces called geomorphic agents. These agents shape the land mainly through two processes: erosion, which is the wearing away of rocks and soil, and deposition, which is the laying down of the eroded materials in new places. The major geomorphic agents include running water, groundwater, glaciers, waves and currents, and wind. Each agent works differently depending on the environment, creating a variety of landforms on the Earth’s surface.
Also Read:
- NCERT Solutions and Notes for Class 7 Geography Chapter 7: Life in the Deserts (Free PDF)
- NCERT Class 7 Geography Chapter 3 ‘Our Changing Earth’: Notes and Solutions (Free PDF)
Running Water
Running water (rivers and streams) is the most active agent shaping landforms in humid regions. It erodes the earth’s surface through:
- Hydraulic action: Force of water removes rock particles.
- Abrasion: Rocks and sediments scrape and grind the riverbed.
- Corrosion: Chemical action dissolves rocks.
- Attrition: Rocks and pebbles collide, breaking into smaller pieces.
Stages of River and Landform Development
| Stage | Characteristics | Landform Examples |
| Youth | Steep slopes, deep V-shaped valleys, rapid flow | Waterfalls, rapids, potholes |
| Mature | Gentler slopes, wider valleys, meanders develop | Floodplains, meanders |
| Old | Very gentle slopes, wide floodplains, deposition dominates | Oxbow lakes, natural levees |
Landforms Created by Running Water
Running water is one of the most powerful forces shaping the Earth’s surface. It can both wear away the land by erosion and build new landforms by depositing sediments. These processes create a variety of landforms depending on the river’s stage and environment.
a) Erosional Landforms
1. Valleys:
- Youthful Rivers: In their early stage, rivers have strong downward cutting power, called vertical erosion. This causes them to carve narrow and deep V-shaped valleys. The sides of these valleys are usually steep and the river channel is narrow and fast-flowing.
- Mature Rivers: As rivers age, they begin to erode sideways more than downwards. This lateral erosion widens the valley floor, making the valley broader and the river slower with a wider channel. The slopes of mature valleys are gentler compared to youthful valleys.
2. Potholes: These are circular holes formed in the riverbed when stones or pebbles caught in swirling currents (called eddies) rotate and grind against the bedrock. Over time, this continuous grinding action creates deep, rounded holes in the riverbed.
3. Plunge Pools: At the base of waterfalls, the force of falling water is very strong. This energy erodes the riverbed, forming deep basins known as plunge pools. These pools can be quite deep and often grow larger over time as erosion continues.
4. Incised Meanders: Normally, rivers meander or curve on flat plains. However, when the land is uplifted due to tectonic forces, the river cuts deeply into the bedrock while maintaining its winding pattern. This results in deep, winding valleys called incised meanders.
5. River Terraces: When a river cuts downwards into its bed, it leaves behind old floodplains at higher levels along its sides. These elevated flat surfaces are called river terraces. They appear as steps or benches along the valley and mark previous levels of the riverbed.
b) Depositional Landforms
1. Alluvial Fans: When a fast-flowing mountain river emerges from a steep slope onto a flat plain, it loses speed suddenly. Because the river slows down, it cannot carry as much sediment, so it deposits the sediments in a fan-shaped pattern called an alluvial fan. These fans are made up of gravel, sand, and silt and are usually found at the base of mountain ranges.
2. Deltas: At the mouth of a river, where it flows into a sea, lake, or ocean, the river slows down and deposits large amounts of sediment. Over time, these sediments accumulate and create new landforms called deltas. Deltas often have a triangular or fan shape and are rich in fertile soil, making them important for agriculture and human settlement. Based on these features, deltas are classified into different types:
| Type | Shape/Feature | Example |
| Arcuate | Fan-shaped with many distributaries | Nile Delta (Egypt) |
| Bird’s Foot | Finger-like projections | Mississippi Delta (USA) |
| Cuspate | Pointed or tooth-shaped | Tiber Delta (Italy) |
3. Floodplains: Floodplains are flat and wide areas found alongside mature rivers. During floods, rivers overflow and spread water across the nearby land. As the floodwater slows down, it deposits fine sediments like silt and clay on both sides of the river. Over time, repeated flooding builds up these flat, fertile plains, which are ideal for farming.
4. Natural Levees: When a river floods, it often deposits heavier sediments like sand and gravel right next to its banks, while finer materials travel farther. These heavier materials pile up to form raised embankments called natural levees. These levees run parallel to the river and can offer some protection from future floods.
5. Point Bars: Rivers often curve in wide loops called meanders. On the inner side of these bends, the water flow is slower, causing sediments to settle and form small, crescent-shaped deposits called point bars. These bars gradually grow over time and may even shift the river’s course slightly.
6. Meanders: Meanders are large, looping bends in a river, usually found in its middle and lower course. These form because water flows faster on the outer banks and slower on the inner banks. This causes erosion on the outside and deposition on the inside, making the river bend more over time.
7. Oxbow Lakes: Sometimes, a meander becomes so curved that the river eventually cuts through the narrow neck of the loop during a flood. This leaves behind a U-shaped or crescent-shaped water body called an oxbow lake. Over time, these lakes may dry up and become marshes or meadows.
8. Braided Channels: When a river carries a large amount of sediment, especially in mountainous or glacial regions, it may split into several smaller channels that weave around sediment bars. This network of interlacing streams is called a braided channel. It forms where the river flow is not strong enough to carry all its sediment in one single channel.
Groundwater
Groundwater moves beneath the Earth’s surface and interacts with soluble rocks like limestone. As it flows, it dissolves these rocks through chemical processes, especially carbonation. Over time, this chemical erosion forms unique underground and surface landforms. These landforms are divided into two categories: erosional and depositional.
Landforms Created by Groundwater
Groundwater, through chemical erosion and deposition, shapes unique landforms, especially in regions with limestone. These landforms can be grouped into two categories based on how they are formed:
a) Erosional Features
| Landform | Description |
| Sinkholes | Circular depressions formed by collapse of underground caves |
| Lapiés | Grooved limestone surfaces created by chemical erosion |
| Caves | Underground hollow spaces formed by limestone dissolution |
| Uvalas | Large depressions formed by merging sinkholes |
| Blind Valleys | Valleys where surface streams disappear underground |
b) Depositional Features
| Landform | Description |
| Stalactites | Icicle-shaped mineral deposits hanging from cave ceilings |
| Stalagmites | Deposits rising from cave floors |
| Pillars | Formed when stalactites and stalagmites meet |
Glaciers
Glaciers are large, thick masses of ice that slowly move downhill under the force of gravity. They shape the land by two main processes: plucking (where rocks are pulled out from the ground) and abrasion (where the ice grinds against the land, wearing it down). As glaciers move, they also carry and deposit sediments, forming features like moraines. Glaciers are mostly found in polar areas and high mountain regions where temperatures remain low enough for ice to persist year-round.
Landforms Created by Glaciers
Glaciers shape the landscape through powerful erosional and depositional processes as they move slowly over land. The landforms created by glaciers can be divided into two main types:
a) Erosional Landforms
| Landform | Description |
| Cirques | Bowl-shaped hollows at glacier heads |
| Horns | Sharp pyramid-shaped peaks from glacier erosion |
| Aretes | Knife-edge ridges between cirques |
| Glacial Valleys | U-shaped valleys carved by glaciers |
| Hanging Valleys | Smaller valleys “hanging” above main valleys |
b) Depositional Landforms
| Landform | Description |
| Moraines | Ridges of debris left by glaciers |
| Eskers | Long ridges from sediment deposited by meltwater streams |
| Drumlins | Smooth, elongated hills indicating ice flow |
| Outwash Plains | Flat plains formed by sediments deposited by glacial meltwater |
Waves and Currents
Coastal landforms are created by the strong force of waves that wear away rocks and cliffs along the shore. At the same time, ocean currents carry and deposit sand and other materials in different areas, helping to build new landforms like beaches and sandbars. Together, these processes constantly change the shape of the coastline.
Landforms Created by Waves and Currents
Waves and currents continuously shape coastlines by eroding rock and depositing sediments. The landforms created by these processes are of two main types:
a) Erosional Landforms
| Landform | Description |
| Cliffs | Steep rock faces formed by wave erosion |
| Wave-cut Platforms | Flat terraces at cliff bases formed by wave erosion |
| Caves | Hollow spaces eroded at cliff base |
| Stacks | Isolated rock columns after collapse of arches |
b) Depositional Landforms
| Landform | Description |
| Beaches | Sand or pebble deposits along the shore |
| Dunes | Sand hills formed by wind near beaches |
| Bars, Spits, Islands | Sand deposits formed by longshore drift |
Wind
Wind mainly shapes landforms in deserts and dry areas where there are very few plants to hold the soil in place. Because there is little vegetation, the wind can easily pick up and carry loose sand and dust, moving it from one place to another and creating different types of landforms like sand dunes and desert pavements.
Landforms Created by Wind
Wind is a powerful agent of erosion and deposition, especially in dry and arid regions. The landforms created by wind can be classified into two types:
a) Erosional Landforms
| Landform | Description |
| Deflation Hollows | Depressions formed by wind removing fine particles |
| Pedestal Rocks | Rocks with narrow bases due to wind erosion |
| Ventifacts | Rocks polished and shaped by wind-blown sand |
| Desert Pavements | Surfaces covered with tightly packed stones |
b) Depositional Landforms
| Landform | Description |
| Sand Dunes | Hills or ridges of sand formed by wind deposition |
| Loess Deposits | Fine silt deposits blown by wind forming fertile soils |
Also Read:
- NCERT Solutions and Notes for Class 7 Geography Chapter 5: Water (Free PDF)
- NCERT Class 7 Geography Chapter 4 ‘Air’: Notes and Solutions (Free PDF)
Important Definition in NCERT Notes Class 11 Geography Fundamentals of Geography Chapter 6 Landforms and their Evolution
This chapter helps us understand how different landforms are created and changed over time by natural processes. Here are some important terms from the chapter, explained in a simple way to make them easy to remember:
- Landform: A natural feature on the Earth’s surface such as mountains, valleys, plateaus, and plains.
- Erosion: The process by which natural forces like water, wind, ice, or gravity wear away rocks and soil from the Earth’s surface.
- Deposition: The process of dropping or settling of eroded material (like sand, soil, and rocks) at a new place.
- Valley: A low area between hills or mountains, often with a river flowing through it.
- Delta: A landform created at the mouth of a river, where it deposits sediment as it flows into a sea or lake.
- Glacier: A large, slow-moving mass of ice formed from compacted snow in cold regions.
- Moraines: Accumulations of rock and soil debris left behind by moving glaciers.
- Sinkhole: A circular depression formed when underground caves collapse, commonly found in limestone areas.
- Stalactite: An icicle-shaped mineral deposit hanging from the ceiling of a cave.
- Stalagmite: A mineral deposit rising from the floor of a cave, formed by dripping water.
- Alluvial Fan: A fan-shaped deposit of sediment formed when a fast-flowing mountain stream slows down onto a plain.
- Oxbow Lake: A crescent-shaped lake formed when a river meander is cut off from the main river channel.
- Meander: A wide bend or curve in a river, formed by erosion on the outer bank and deposition on the inner bank.
- Mass Movement: The downhill movement of soil, rock, and debris under the influence of gravity.
- Erosion Agents: Natural forces like water, wind, glaciers, and waves that cause erosion.
Explore Notes of Class 11 Fundamentals of Geography
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FAQs
Rivers create V-shaped valleys in their youthful stage through strong vertical erosion (cutting downwards). As they mature, rivers shift to lateral erosion (cutting sideways) and deposition, leading to the formation of wide, flat floodplains when they overflow and deposit sediments.
Groundwater primarily shapes land through chemical dissolution of soluble rocks (like limestone), creating features such as sinkholes and caves. Glaciers, on the other hand, shape land through powerful physical processes like plucking (pulling out rocks) and abrasion (grinding against the land), resulting in U-shaped valleys and moraines.
Two erosional landforms created by wind are deflation hollows (depressions where wind removes fine particles) and pedestal rocks (rocks with narrow bases due to wind erosion). Two depositional landforms created by wind are sand dunes (hills of sand) and loess deposits (fine silt deposits forming fertile soils).
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