Class 11 : Geography (In English) – Lesson 6. Landforms and their Evolution
EXPLANATION & SUMMARY
📘 1. Detailed Explanation (~1700+ Words)
🌍 Introduction
🌏 The Earth’s surface is a dynamic and ever-changing landscape, continuously shaped and reshaped by powerful natural forces operating both within and on the planet. The visible features we observe — mountains, valleys, plateaus, plains, deserts, river basins, coastlines, and more — are known as landforms. These landforms are products of geomorphic processes that have acted over millions of years and continue to shape the Earth today.
🪨 The study of landforms, their structure, origin, and evolution is called geomorphology. Understanding how landforms evolve helps explain Earth’s past, understand natural hazards, predict future landscape changes, and manage natural resources.
🌄 Meaning of Landforms
🏞️ Landforms are natural physical features of the Earth’s surface shaped by geomorphic processes. They vary in size, shape, elevation, composition, and origin — from towering mountains to deep valleys, and from vast plains to tiny sand dunes.
They are broadly classified into:
🌋 Endogenic Landforms — formed by internal forces (e.g., fold mountains, volcanic cones).
🌦️ Exogenic Landforms — formed by external forces (e.g., river valleys, sand dunes, deltas).
🪐 Forces Responsible for Landform Formation
Two major sets of forces shape Earth’s landforms:
🌋 1. Endogenic Forces (Internal Forces)
🔦 These originate from within the Earth and are driven by internal heat, pressure, and tectonic activity. They build up the Earth’s surface and create new landforms.
📍 Types:
🏔️ Orogenic Movements: Form fold mountains (e.g., Himalayas).
🏜️ Epeirogenic Movements: Create plateaus and basins.
🌋 Volcanic Activity: Forms volcanic cones, lava plateaus.
🌍 Earthquakes: Create faults, rift valleys.
🌦️ 2. Exogenic Forces (External Forces)
🌤️ These act on the Earth’s surface, powered by solar energy and gravity. They wear down the elevated surfaces built by endogenic forces and reshape them.
📍 Processes:
🌧️ Weathering: Breaking down rocks.
🏔️ Erosion: Wearing away and removal of materials.
🪨 Transportation: Movement of sediments.
🏞️ Deposition: Laying down of eroded material.
The continuous interaction between endogenic construction and exogenic destruction creates and evolves landforms.
🏔️ Classification of Landforms
Landforms can be classified into three categories based on their origin and structure:
🪨 1. Primary Landforms (Tectonic)
Formed directly by endogenic processes.
Examples: Fold mountains (Himalayas), rift valleys (East African Rift), plateaus (Deccan Plateau).
🌋 2. Secondary Landforms (Erosional)
Formed by the removal of material through agents like water, wind, and ice.
Examples: V-shaped valleys, canyons, glacial cirques.
🏞️ 3. Tertiary Landforms (Depositional)
Created by the deposition of sediments transported by agents.
Examples: Deltas, sand dunes, moraines, alluvial plains.
🌊 Landforms Created by Different Geomorphic Agents
Various natural agents shape the Earth’s surface differently. Each agent erodes, transports, and deposits material, creating characteristic landforms.
💦 I. Fluvial Landforms (Running Water)
🏞️ Rivers are among the most powerful geomorphic agents. They erode, transport, and deposit sediments, creating distinctive landforms over time.
🏔️ A. Erosional Landforms
🏞️ V-Shaped Valleys: Formed by vertical erosion in youthful rivers (e.g., Indus Valley).
⛲ Gorges and Canyons: Deep, narrow valleys formed by intense down-cutting (e.g., Grand Canyon).
💦 Waterfalls: Sudden vertical drops along a river course.
🌊 Rapids and Cataracts: Irregular riverbeds with steep gradients.
🌿 B. Depositional Landforms
🌊 Floodplains: Flat areas formed by deposition during floods.
🌾 Natural Levees: Raised embankments formed by sediment deposition along riverbanks.
🌊 Alluvial Fans: Fan-shaped deposits at mountain foothills.
🏞️ Deltas: Landforms formed where rivers meet standing water bodies (e.g., Ganga-Brahmaputra Delta).
🌬️ II. Aeolian Landforms (Wind)
🌬️ Wind acts as a powerful erosional and depositional agent in arid and semi-arid regions.
🪨 A. Erosional Landforms
🌪️ Deflation Hollows: Depressions formed by removal of loose particles.
🍄 Mushroom Rocks: Rocks eroded into mushroom shapes.
🪨 Yardangs: Streamlined ridges carved by wind.
🏜️ B. Depositional Landforms
🌵 Sand Dunes: Accumulations of sand formed by wind deposition (e.g., Barchans, Seif dunes).
🌬️ Loess Deposits: Fine dust transported and deposited over large areas.
❄️ III. Glacial Landforms (Ice)
🧊 Glaciers shape landscapes through erosion, transportation, and deposition in cold regions.
🏔️ A. Erosional Landforms
🪓 Cirques: Bowl-shaped depressions at glacier heads.
🏞️ U-Shaped Valleys: Glacially eroded valleys with a flat floor and steep sides.
🏔️ Aretes and Horns: Sharp ridges and pointed peaks formed by glacial erosion.
🏞️ B. Depositional Landforms
🪨 Moraines: Deposits of glacial debris.
❄️ Drumlins: Oval-shaped hills formed under glaciers.
🌊 Eskers: Long ridges formed by glacial meltwater streams.
🌊 IV. Coastal Landforms (Waves and Tides)
🌊 Coastal regions are shaped by wave action, tides, and marine currents.
🌊 A. Erosional Landforms
🪨 Cliffs and Wave-Cut Platforms: Vertical rock faces formed by wave erosion.
🏝️ Sea Caves, Arches, and Stacks: Progressive erosion of headlands.
🏖️ B. Depositional Landforms
🏝️ Beaches: Accumulations of sand and pebbles.
🌊 Spits and Bars: Narrow ridges formed parallel or oblique to the coast.
🌾 Lagoons: Shallow water bodies formed behind spits or bars.
🌊 V. Karst Landforms (Groundwater)
💧 Groundwater dissolves soluble rocks like limestone, creating unique landforms known as karst landscapes.
🪨 A. Erosional Landforms
🕳️ Sinkholes: Circular depressions formed by rock dissolution.
🌊 Caves: Underground chambers formed by water erosion.
🪶 Limestone Pavements: Flat, exposed limestone surfaces.
🌿 B. Depositional Landforms
🪨 Stalactites: Icicle-like structures hanging from cave ceilings.
🏞️ Stalagmites: Cone-shaped deposits rising from cave floors.
🌋 Pillars: Formed when stalactites and stalagmites meet.
🌎 Evolution of Landforms: Geomorphic Cycles
Landforms evolve over time through geomorphic cycles — stages of development proposed by geomorphologists.
🪐 Davis’ Geographical Cycle of Erosion
Proposed by William Morris Davis, this model explains landform evolution in stages:
🌱 Youth: Rapid vertical erosion forms deep valleys and waterfalls.
🌿 Maturity: Lateral erosion widens valleys; floodplains develop.
🌾 Old Age: Minimal relief, formation of peneplains.
🌋 Penck’s Theory of Morphological Development
German geographer W. Penck emphasized the role of uplift and erosion acting simultaneously, resulting in varied slopes and landforms.
🏔️ Hack’s Dynamic Equilibrium Theory
Hack suggested landscapes evolve toward a dynamic equilibrium where erosion and uplift balance each other.
🌐 Factors Influencing Landform Evolution
The nature and rate of landform evolution depend on several factors:
🪨 Structure of Rocks: Hardness, composition, and arrangement affect resistance to erosion.
🌍 Climatic Conditions: Rainfall, temperature, and vegetation influence weathering and erosion.
🏔️ Relief and Gradient: Steep slopes encourage erosion; gentle slopes favor deposition.
🌊 Time: Longer geological timescales allow more profound changes.
🔥 Human Activity: Mining, deforestation, and urbanisation accelerate landscape changes.
🌄 Landform Evolution and Human Life
Landforms profoundly influence human activities:
🌆 Settlement Patterns: Plains and river valleys support dense populations.
🚜 Agriculture: Fertile floodplains and deltas are ideal for cultivation.
🪨 Resource Distribution: Mountains and plateaus contain minerals and water sources.
🏔️ Tourism: Mountains, caves, and coastal features attract visitors.
⚠️ Hazards: Earthquakes, landslides, and floods are linked to geomorphic activity.
📊 Interrelationship Between Endogenic and Exogenic Processes
Landforms are a result of continuous interaction between endogenic (constructive) and exogenic (destructive) forces.
🌋 Endogenic forces uplift and create relief — mountains, plateaus, volcanic cones.
🌦️ Exogenic forces sculpt and modify this relief — carving valleys, shaping plains, and forming new features.
Example:
The Himalayas (endogenic uplift) → carved by rivers and glaciers (exogenic).
Volcanic plateaus → eroded into mesas and buttes.
📚 2. Summary (~300 Words)
Landforms are natural features of the Earth’s surface shaped by internal and external forces. They result from the interaction of endogenic forces (tectonic movements, volcanism, earthquakes) and exogenic forces (weathering, erosion, deposition). Landforms are classified as primary (formed by tectonic activity), secondary (formed by erosion), and tertiary (formed by deposition).
Different geomorphic agents create distinct landforms: rivers form valleys and deltas; wind forms dunes and deflation hollows; glaciers create cirques and moraines; waves shape cliffs and beaches; groundwater forms caves and stalactites. Landforms evolve through geomorphic cycles described by Davis, Penck, and Hack, progressing through youth, maturity, and old age.
The evolution of landforms is influenced by rock structure, climate, relief, time, and human activities. They are vital for human life, affecting settlement, agriculture, resource distribution, and hazards. The continuous interaction between constructive internal forces and destructive external forces ensures that Earth’s surface remains dynamic and ever-changing.
Understanding landform evolution helps explain Earth’s geological history, predict natural hazards, and manage land sustainably. The landscapes we see today are the result of millions of years of geomorphic processes that continue to shape the planet.
⚡ 3. Quick Recap (~100 Words)
Landforms are natural features formed by internal and external forces. Endogenic processes build relief through folding, faulting, and volcanism, while exogenic processes sculpt it through weathering, erosion, and deposition. Rivers carve valleys and deltas, wind shapes dunes, glaciers form cirques and moraines, and waves create cliffs and beaches. Landforms evolve over time through geomorphic cycles, influenced by rock type, climate, relief, and human activity. They impact human settlement, agriculture, and resources. The constant interaction of endogenic and exogenic forces keeps Earth’s surface dynamic and ever-changing.
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QUESTIONS FROM TEXTBOOK
✨ 1. Multiple Choice Questions (MCQs)
🔴 Q1: In which of the following stages of landform development, downward cutting is dominated?
🟢 (a) Youth stage
🔵 (b) Late mature stage
🟡 (c) Early mature stage
🟣 (d) Old stage
✅ Answer: 🟢 (a) Youth stage
🔵 Q2: A deep valley characterised by steep step-like side slopes is known as:
🟢 (a) U-shaped valley
🔵 (b) Gorge
🟡 (c) Blind valley
🟣 (d) Canyon
✅ Answer: 🔵 (b) Gorge
🟡 Q3: In which one of the following regions the chemical weathering process is more dominant than the mechanical process?
🟢 (a) Humid region
🔵 (b) Limestone region
🟡 (c) Arid region
🟣 (d) Glacier region
✅ Answer: 🔵 (b) Limestone region
🟣 Q4: Which one of the following sentences best defines the term ‘Lapies’?
🟢 (a) A small to medium-sized shallow depression
🔵 (b) A landform whose opening is more or less circular at the top and funnel-shaped towards bottom
🟡 (c) A landform formed due to dripping water from the surface
🟣 (d) An irregular surface with sharp pinnacles, grooves, and ridges
✅ Answer: 🟣 (d) An irregular surface with sharp pinnacles, grooves, and ridges
🔵 Q5: A deep, long, and wide trough or basin with very steep concave high walls at its head as well as in sides is known as:
🟢 (a) Cirque
🔵 (b) Glacial valley
🟡 (c) Lateral moraine
🟣 (d) Esker
✅ Answer: 🔵 (b) Glacial valley
✏️ 2. Short Answer Questions (About 30 Words Each)
🔴 Q1: What do incised meanders in rocks and meanders in plains of alluvium indicate?
🌱 Answer: Incised meanders indicate rejuvenation of a river, often due to upliftment of land or a fall in sea level. Meanders in plains of alluvium show mature river stages with lateral erosion.
🔵 Q2: Explain the evolution of valley sinks or uvalas.
🌱 Answer: Valley sinks or uvalas evolve when several dolines or sinkholes merge due to continuous chemical weathering and erosion in limestone regions, forming large depressions on the surface.
🟡 Q3: Underground flow of water is more common than surface run-off in limestone areas. Why?
🌱 Answer: Limestone is highly permeable and soluble, allowing water to percolate quickly and flow underground. Solution channels and caves form easily, reducing surface water flow.
🟣 Q4: Glacial valleys show up many linear depositional forms. Give their locations and names.
🌱 Answer: Glacial valleys often feature depositional landforms like moraines (Alps, Himalayas), drumlins (Northern Europe), eskers (Canada), and outwash plains (Iceland).
🔵 Q5: How does wind perform its task in desert areas? Is it the only agent responsible for the erosional features in the deserts?
🌱 Answer: Wind performs erosion through deflation, abrasion, and attrition. It is not the only agent — water action from occasional rainfall also contributes significantly to desert erosion.
📜 3. Long Answer Questions (About 150 Words Each)
🔴 Q1: Running water is by far the most dominating geomorphic agent in shaping the earth’s surface in humid as well as arid climates. Explain.
🌱 Answer: Running water is a powerful geomorphic agent due to its ability to erode, transport, and deposit sediments. In humid regions, rivers shape landscapes by carving valleys, forming meanders, floodplains, and deltas. In arid climates, ephemeral streams and flash floods erode valleys and create landforms such as wadis, alluvial fans, and playas. Over geological timescales, rivers cut deep gorges and canyons and contribute to continental drainage systems. Their dynamic action continuously reshapes the surface, redistributing sediments and forming diverse landforms. Whether in a humid or dry region, water’s erosive power and ability to sculpt the land make it the most dominant geomorphic force on Earth.
🔵 Q2: Limestones behave differently in humid and arid climates. Why? What is the dominant and almost exclusive geomorphic process in limestone areas and what are its results?
🌱 Answer: Limestone’s solubility in water containing carbonic acid leads to contrasting behaviours. In humid climates, solution weathering dominates, forming features like sinkholes, dolines, uvalas, caves, and karst landscapes. In arid climates, solution processes are limited due to low moisture, and physical weathering is more significant. The dominant geomorphic process in limestone regions is carbonation — carbon dioxide reacts with water to dissolve calcium carbonate. The result is distinctive karst topography, including underground drainage, stalactites, stalagmites, and disappearing streams.
🟡 Q3: How do glaciers accomplish the work of reducing high mountains into low hills and plains?
🌱 Answer: Glaciers are powerful erosional agents that reshape landscapes through processes like plucking, abrasion, and freeze-thaw weathering. They erode mountains by carving deep U-shaped valleys, cirques, and fjords while transporting massive amounts of debris. The eroded material is deposited as moraines, drumlins, and outwash plains, gradually lowering the elevation of mountain regions. Over time, repeated glacial advances and retreats transform rugged mountainous terrain into gentler hills and expansive plains. This continuous erosion and deposition by glaciers significantly modify the Earth’s surface and contribute to landscape evolution.
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OTHER IMPORTANT QUESTIONS FOR EXAMS
🌏 Section A — Multiple Choice Questions (1 mark each)
🔵 Question 1: Which of the following is the primary factor influencing landform development?
🟢 1️⃣ Geomorphic processes
🔴 2️⃣ Latitude
🟡 3️⃣ Soil type
🔴 4️⃣ Human activity
✔️ Answer: Geomorphic processes
🟡 Question 2: Which of the following is an example of an erosional landform?
🟢 1️⃣ Alluvial fan
🔴 2️⃣ River delta
🟡 3️⃣ Canyon
🔴 4️⃣ Beach ridge
✔️ Answer: Canyon
🔴 Question 3: Which process is responsible for the formation of depositional landforms?
🟢 1️⃣ Weathering
🔴 2️⃣ Erosion
🟡 3️⃣ Deposition
🔴 4️⃣ Folding
✔️ Answer: Deposition
🟢 Question 4: Landforms created by running water are called:
🟢 1️⃣ Fluvial landforms
🔴 2️⃣ Aeolian landforms
🟡 3️⃣ Glacial landforms
🔴 4️⃣ Karst landforms
✔️ Answer: Fluvial landforms
🔵 Question 5: Which of the following features is formed due to glacial erosion?
🟢 1️⃣ Cirque
🔴 2️⃣ Moraine
🟡 3️⃣ Drumlin
🔴 4️⃣ Outwash plain
✔️ Answer: Cirque
🟡 Question 6: Wind is the dominant agent of erosion and deposition in:
🟢 1️⃣ Arid regions
🔴 2️⃣ Coastal areas
🟡 3️⃣ Mountainous regions
🔴 4️⃣ Glacial valleys
✔️ Answer: Arid regions
🔴 Question 7: Which of the following features is associated with karst topography?
🟢 1️⃣ Cirque
🔴 2️⃣ Sinkhole
🟡 3️⃣ Meander
🔴 4️⃣ Sand dune
✔️ Answer: Sinkhole
🟢 Question 8: Which type of landform is formed when a river overflows its banks and deposits sediments?
🟢 1️⃣ Natural levee
🔴 2️⃣ Delta
🟡 3️⃣ Oxbow lake
🔴 4️⃣ Gorge
✔️ Answer: Natural levee
🔵 Question 9: Which of the following is a depositional feature of a glacier?
🟢 1️⃣ U-shaped valley
🔴 2️⃣ Drumlin
🟡 3️⃣ Hanging valley
🔴 4️⃣ Cirque
✔️ Answer: Drumlin
🟡 Question 10: Which landform is formed due to the wind’s abrasion action in deserts?
🟢 1️⃣ Mushroom rock
🔴 2️⃣ Spit
🟡 3️⃣ Moraine
🔴 4️⃣ Beach
✔️ Answer: Mushroom rock
🔴 Question 11: Stalactites and stalagmites are formed by:
🟢 1️⃣ Glacial action
🔴 2️⃣ Groundwater deposition
🟡 3️⃣ Wind erosion
🔴 4️⃣ River erosion
✔️ Answer: Groundwater deposition
🟢 Question 12: The landform formed by river meandering and cutting off loops is called:
🟢 1️⃣ Oxbow lake
🔴 2️⃣ Delta
🟡 3️⃣ Alluvial fan
🔴 4️⃣ Gorge
✔️ Answer: Oxbow lake
🧭 Section B — Short Answer Questions (15–20 words each)
🔵 Question 13: What are landforms?
🟢 Answer: Landforms are natural physical features of the Earth’s surface formed by various geomorphic processes.
🟡 Question 14: Define erosion.
🟢 Answer: Erosion is the process of wearing away and removal of rocks and soil by agents like water, wind, and ice.
🔴 Question 15: What is deposition?
🟢 Answer: Deposition is the laying down of sediments transported by geomorphic agents like rivers, glaciers, and wind.
🟢 Question 16: Mention two examples of fluvial landforms.
🟢 Answer: Two examples of fluvial landforms are meanders and river deltas.
🔵 Question 17: What are glacial landforms?
🟢 Answer: Glacial landforms are land features created by the erosional and depositional activity of moving ice masses.
🟡 Question 18: What is karst topography?
🟢 Answer: Karst topography forms in limestone regions due to chemical weathering, creating features like sinkholes and caves.
🔴 Question 19: What are aeolian landforms?
🟢 Answer: Aeolian landforms are created by wind erosion and deposition, common in deserts, such as dunes and mushroom rocks.
🟢 Question 20: What is an oxbow lake?
🟢 Answer: An oxbow lake is a crescent-shaped water body formed when a meander is cut off from the main river.
🌍 Section C — Medium Answer Questions (≈60 words each)
🔵 Question 21: Explain the role of running water in shaping landforms.
🟢 Answer: Running water is a powerful geomorphic agent. It erodes rock through hydraulic action, abrasion, and solution, forming valleys, gorges, and waterfalls. Deposition occurs when velocity decreases, creating features like floodplains, levees, deltas, and alluvial fans. Over time, rivers carve landscapes, transport sediments, and shape dynamic fluvial landforms through erosion, transportation, and deposition.
🟡 Question 22: Describe the landforms formed by glacial erosion.
🟢 Answer: Glacial erosion creates several distinctive landforms. Cirques are amphitheatre-shaped basins at valley heads. U-shaped valleys form as glaciers deepen and widen river valleys. Hanging valleys result from tributary glaciers joining larger ones. Aretes and horns are sharp ridges and peaks formed by glacier erosion on multiple sides of mountains. These features reshape mountain landscapes.
🔴 Question 23: Differentiate between erosional and depositional landforms.
🟢 Answer: Erosional landforms result from the removal of materials by agents, such as valleys, canyons, and cirques. Depositional landforms form when transported materials are laid down, including deltas, moraines, sand dunes, and floodplains. While erosional landforms reflect the destructive power of geomorphic agents, depositional landforms demonstrate their constructive activity, often creating new landscapes.
🟢 Question 24: What are karst landforms? Mention their main features.
🟢 Answer: Karst landforms form in limestone regions due to chemical weathering, particularly carbonation. Rainwater reacts with limestone, dissolving it and creating unique features. These include sinkholes (depressions), caves and caverns (underground chambers), stalactites and stalagmites (depositional features inside caves), and limestone pavements. Karst landscapes are characterized by subterranean drainage and lack of surface streams.
🔵 Question 25: Explain the process and landforms associated with wind erosion.
🟢 Answer: In arid regions, wind erodes through deflation (removal of loose particles) and abrasion (scraping surfaces). This creates features like deflation hollows, ventifacts, and mushroom rocks. Wind also transports and deposits materials, forming sand dunes and loess plains. Aeolian processes constantly reshape desert landscapes, creating distinctive erosional and depositional features.
🟡 Question 26: Describe the role of groundwater in landform development.
🟢 Answer: Groundwater shapes landscapes mainly through chemical weathering and deposition. It dissolves soluble rocks like limestone, forming sinkholes, caves, and underground streams. Over time, water dripping in caves forms stalactites (hanging) and stalagmites (rising). These features create karst landscapes. Groundwater action is slow but significant, creating unique subterranean landforms and influencing surface drainage.
🏞️ Section D — Detailed Answer Questions (≈150 words each)
🔴 Question 27: Describe the major landforms formed by river action.
🟢 Answer: Rivers shape landscapes through erosion, transportation, and deposition. In the upper course, they erode vertically, forming V-shaped valleys, waterfalls, gorges, and interlocking spurs. In the middle course, lateral erosion and deposition create meanders, floodplains, and river terraces. In the lower course, deposition dominates, forming deltas, levees, and distributaries. Erosional features like gorges and canyons reflect the river’s cutting power, while depositional features like alluvial fans and deltas show sediment buildup. Over time, rivers also form oxbow lakes when meanders are cut off. These landforms are dynamic and evolve with changing flow, sediment load, and base level. River activity is a major factor in shaping continental surfaces, influencing soil fertility, ecosystem distribution, and human settlement patterns.
🟢 Question 28: Explain the erosional and depositional features created by glaciers.
🟢 Answer: Glaciers sculpt landscapes through erosion and deposition. Erosional features include:
Cirques: Bowl-shaped depressions where glaciers originate.
U-shaped valleys: Deep, wide valleys formed by glacier movement.
Horns and Aretes: Sharp peaks and ridges shaped by erosion on multiple sides.
Hanging valleys: Elevated valleys formed by tributary glaciers.
Depositional features form when glaciers retreat and leave sediments. These include moraines (ridges of debris), drumlins (streamlined hills), eskers (long ridges from subglacial streams), and outwash plains (sorted sediments beyond glaciers). These features influence drainage patterns, soil distribution, and landscape structure. Glacial landforms are significant for understanding past climatic conditions and glacial movements.
🔵 Question 29: Discuss the major depositional landforms formed by wind.
🟢 Answer: Wind creates several depositional landforms in arid and semi-arid regions. Sand dunes form when wind velocity decreases, depositing sand. They vary in shape: barchans (crescent-shaped), seif dunes (longitudinal), and parabolic dunes (U-shaped). Loess plains consist of fine silt and clay carried over long distances and deposited over large areas. Sand sheets cover flat surfaces with thin layers of sand. These features indicate wind direction, strength, and sediment supply. They also influence soil fertility and desert ecology. Over time, wind deposition transforms barren deserts into diverse landscapes, creating habitats and affecting land use. Aeolian deposition plays a significant role in global sediment transport and landscape evolution.
🟡 Question 30: Discuss the stages of landform development according to the Davisian cycle of erosion.
🟢 Answer: William Morris Davis proposed the Geographical Cycle of Erosion, explaining landscape evolution in three main stages:
Youth: Rivers cut deep valleys and waterfalls; relief is steep and rugged.
Maturity: Valleys widen, meanders form, and relief decreases as erosion balances uplift.
Old Age: Landscape becomes a peneplain with minimal relief; deposition dominates.
Davis emphasized the balance between uplift and erosion, showing how landscapes evolve over time. External factors like climate, lithology, and tectonics influence the pace of these stages. Although later modified by geomorphologists, Davis’s model remains foundational in understanding landform evolution and river landscape development. It highlights the dynamic nature of Earth’s surface and the continuous interaction of constructive and destructive forces shaping it.
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ONE PAGE REVISION SHEET
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MIND MAPS
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