LANDFORMS

A landform is a natural or artificial feature of the Earth's surface, typically formed through various geological processes over time. These features can include mountains, valleys, hills, plains, plateaus, deserts, rivers, lakes, and other physical formations. Landforms are diverse and can be found on the continents, ocean floors, and even on other celestial bodies.

Natural landforms are shaped by processes such as erosion, weathering, tectonic activity, volcanic activity, and sedimentation. For example, mountains may be formed through tectonic plate movements, while valleys can be carved out by rivers or glaciers. Human activities can also contribute to the creation of artificial landforms, such as dams, canals, and terraced fields.

Classification of Major Landforms of Earth

The Earth's surface is adorned with a diverse array of landforms, each shaped by a unique interplay of geological forces. These landforms can be broadly classified into three major categories based on their elevation and slope:

1. Mountains: Towering giants that pierce the sky, mountains are some of the most awe-inspiring landforms on Earth. They are characterized by their high elevation and steep slopes, often rising several kilometers above the surrounding landscape

• Formation: Mountains are primarily formed by two main processes: folding and uplift. Folding occurs when immense tectonic plates collide, pushing massive layers of rock upwards to form towering ranges. Uplift, on the other hand, involves the vertical movement of large blocks of Earth's crust, resulting in the creation of isolated mountains or plateaus.
• Types: There are three main types of mountains:
  • Fold mountains: Formed by the folding of sedimentary rocks, these mountains are typically characterized by long, linear ranges with sharp peaks and valleys. Examples include the Himalayas, the Rockies, and the Andes.
  • Fault-block mountains: These mountains are created when large blocks of Earth's crust are uplifted or dropped along fault lines. They often have steep, angular faces and flat tops. Examples include the Sierra Nevada and the Vosges Mountains.
  • Volcanic mountains: Formed by the accumulation of lava and ash ejected from volcanoes, these mountains can be conical or shield-shaped. Examples include Mount Fuji and Mount Kilimanjaro

• Formation: Plateaus can be formed through various processes, including:
  • Uplift: Similar to mountains, plateaus can be formed by the vertical movement of large crustal blocks.
  • Volcanic activity: Extensive lava flows can solidify to form vast plateaus, such as the Deccan Plateau in India.
  • Erosion: Over millions of years, erosion can wear down mountains and hills, leaving behind a flat plateau surface. The Colorado Plateau in the United States is an example.
• Types: Plateaus can be further categorized based on their formation process:
  • Basalt plateaus: Formed by volcanic lava flows, these plateaus are characterized by thick layers of basalt rock. The Columbia Plateau in the northwestern United States is an example.
  • Dissected plateaus: These plateaus have been heavily eroded by rivers and other agents, creating deep canyons and valleys that dissect the plateau surface. The Colorado Plateau is a prime example

Classification of Plateaus

Based on Formation Process:

• Uplift Plateaus: Formed by the vertical movement of large crustal blocks, uplifting the entire region to create a plateau. Examples: Colorado Plateau, Tibetan Plateau.
• Volcanic Plateaus: Formed by the accumulation of lava flows from numerous volcanic eruptions, solidifying into expansive flat surfaces. Examples: Deccan Plateau (India), Ethiopian Highlands.
• Erosional Plateaus: Formed by the erosion of mountains and hills over millions of years, leaving behind a flat plateau surface. Examples: Allegheny Plateau (US), Patagonian Plateau (Argentina).

Based on Location:

• Intermontane Plateaus: Located within mountain ranges, surrounded by high mountains on at least two sides. Examples: Tibetan Plateau, Anatolian Plateau (Turkey).
• Piedmont Plateaus: Situated at the foot of mountains, bordering plains or oceans on the remaining sides. Examples: Piedmont Plateau (US), Deccan Plateau (India).
• Continental Plateaus: Occupying large areas within continents, not directly associated with mountain ranges. Examples: Arabian Peninsula, Brazilian Highlands.

 

 

3. Plains: Expansive stretches of flat or gently rolling land with low elevation, plains are some of the most common landforms on Earth. They provide fertile grounds for agriculture and support diverse ecosystems.

• Formation: Plains are primarily formed by two main processes:
  • Deposition: Over time, rivers, glaciers, and wind can transport and deposit sediments in low-lying areas, gradually building up plains. The Mississippi Alluvial Plain in the United States is an example.
  • Erosion: The erosion of mountains and hills can wear down their elevated features, leaving behind vast plains. The Great Plains of North America were formed in this way.
• Types: Plains can be further classified based on their formation process and location:
  • Floodplains: These flat plains are formed along river courses by the deposition of sediment during floods.
  • Coastal plains: These plains are located along coastlines and are formed by the deposition of sediment from rivers and waves.
  • Interior plains: These plains are located away from coastlines and are formed by various processes, including deposition, erosion, and volcanic activity

Classification of Plains

 

By Formation Process:

• Depositional Plains: These plains are formed by the accumulation of sediments transported and deposited by various agents like rivers, wind, and glaciers.
  • Floodplains: Flat plains bordering rivers, created by sediment deposition during floods
  • Coastal Plains: Low-lying plains along coastlines, formed by sediment deposition from rivers and waves
  • Alluvial Plains: Extensive plains formed by the deposition of alluvium (river-borne sediments) over long periods
  • Loess Plains: Wind-blown plains composed of fine, fertile soil particles called loess.

Erosional Plains: These plains are created by the erosion of pre-existing highlands by wind, water, and ice.

• Peneplains: Gently rolling plains formed by prolonged erosion, nearing a base level of erosion
• Piedmont Plains: Gently sloping plains formed at the base of mountains due to erosion

 

 

 

 

Intrusive landforms

 

Intrusive Landform	Description	Formation
Batholiths	Large, deep-seated intrusive igneous rock formations covering at least 100 sq. km. Often found at the core of mountain ranges.	Slow cooling and solidification of magma deep within the Earth's crust.
Lacoliths	Lens-shaped intrusions causing overlying rocks to arch upward. Smaller in scale compared to batholiths.	Magma intrusion between layers of sedimentary rock, leading to uplift.
Lopoliths	Saucer-shaped intrusive igneous bodies with a flat base and a dome-like top. Have a concave upward shape.	Intrusion of magma into sedimentary rock layers, causing overlying rocks to sag or subside.
Phacoliths	Curved or arched structures resulting from the bending or folding of rock layers due to magma intrusion.	Magma forces surrounding rocks to deform, creating a curved or dome-like structure.
Sills	Tabular, sheet-like intrusions parallel to existing rock layers. Typically horizontal and can extend for considerable distances.	Magma injected between existing rock layers solidifies in a horizontal orientation.
Dykes (Dikes)	Vertical or near-vertical sheet-like intrusions cutting across existing rock layers. Appear as narrow, wall-like structures.	Magma injected into fractures or faults within the Earth's crust, cutting across pre-existing rock layers.

 

 

Landform made by Running Water

 

Landform	Description	Formation Process	Example
Valley	Elongated depression created by erosion from a stream or river	Erosion by water flowing downhill	Grand Canyon, Nile Valley
Gorge	Deep, narrow valley with steep sides	Rapid erosion in hard rock by concentrated water flow	Niagara Gorge, Cheddar Gorge
Canyon	Similar to a gorge, but wider and often with step-like features	Erosion in layered rock formations	Grand Canyon, Yarlung Zangbo Canyon
Meander	A bend in a river with a curved, looping shape	Erosion on outer bank and deposition on inner bank as water flows	Amazon River, Mississippi River
Oxbow Lake	Horseshoe-shaped lake formed when a meander is cut off from the main channel	Change in river course due to erosion and deposition	Horseshoe Lake (Mississippi), Beelzebub Billabong (Australia)
Waterfall	Steep drop in a river where water plunges vertically	Erosion at the edge of a resistant rock layer	Niagara Falls, Victoria Falls
Pothole	Circular depression in rock bed caused by swirling water and abrasive particles	Erosion by water and rocks carried by the current	Devils Kitchen (Utah), Swallow Holes (England)
Floodplain	Flat land adjacent to a river that is periodically flooded	Deposition of sediment during floods	Nile Delta, Ganges Delta
Delta	Triangular deposit of sediment formed at the mouth of a river where it enters a larger body of water	Accumulation of sediment as water slows down and loses carrying capacity	Mississippi Delta, Nile Delta
Alluvial fan	Fan-shaped deposit of sediment formed where a stream flows out of a narrow mountain valley onto a plain	Abrupt decrease in water velocity leading to sediment deposition	Death Valley alluvial fans, Mount Etna alluvial fans

 

 

 

Landform made by Groundwater

 

Landform	Description	Formation
Karst Topography	Terrain characterized by limestone dissolution.	Chemical weathering of soluble bedrock (usually limestone).
Caves	Hollow underground chambers in rock formations.	Dissolution of soluble rock by groundwater over time.
Sinkholes	Depressions in the land surface due to collapse.	Dissolution of underlying soluble rock, often limestone.
Springs	Locations where groundwater emerges at the surface.	Natural discharge of water from an underground aquifer.
Karst Springs	Springs associated with karst topography.	Emergence of groundwater from karst features like caves.
Subterranean Rivers	Rivers flowing beneath the Earth's surface.	Erosion of underground channels by flowing groundwater.
Cenotes	Natural sinkholes or pits with exposed groundwater.	Collapse of cave roofs or dissolution of bedrock creates them.
Artificial Sinkholes	Depressions caused by human activities.	Mining, drilling, or other human activities disrupting the ground.
Artesian Springs	Springs where water flows to the surface under pressure.	Water from a confined aquifer is forced to the surface.
Perched Water Tables	Elevated groundwater tables above the main water table.	Impermeable layer traps water above the main aquifer.
Tufa Terraces	Deposits of calcium carbonate formed by spring water.	Precipitation of minerals as groundwater reaches the surface.

 

Karst Topography

 

Karst topography is a distinctive type of landscape that forms due to the dissolution of soluble rocks, commonly limestone, dolomite, or gypsum. This process is primarily driven by the chemical weathering of these rocks by slightly acidic groundwater. The resulting landforms are characterized by unique features such as sinkholes, caves, underground rivers, and rugged, often barren, terrain. Here are some key aspects of karst topography:

• Formation Process:

  • Karst topography is formed through a process known as karstification or speleogenesis.
  • Rainwater, slightly acidic due to the absorption of carbon dioxide from the atmosphere, infiltrates the ground and reacts with the soluble rock, gradually dissolving it.
  • The dissolution process is enhanced by the presence of joints, fractures, and bedding planes in the rock, creating conduits for water to flow and further dissolve the rock.

• Common Features:

  • Sinkholes: Depressions or holes in the ground formed when the roof of an underground cavern collapses. They can be small or large and may contain standing water.
  • Caves: Hollow underground chambers and passages formed by the dissolution of rock. Stalactites and stalagmites are common cave formations.
  • Dolines (Sinkhole Basins): Large, bowl-shaped depressions on the surface, often containing smaller sinkholes.
  • Poljes: Large flat-bottomed depressions, usually the result of the coalescence of dolines.
  • Karst Springs: Emergence points of underground rivers or groundwater flows on the surface.
  • Uvalas: Wider, elongated depressions formed by the coalescence of dolines and sinkholes.

• Distribution:

  • Karst topography is found worldwide, but it is especially prevalent in areas with soluble rock formations. Notable examples include the karst regions in Slovenia, the Dinaric Alps, the Yucatan Peninsula, and parts of China.

• Land Use and Challenges:

  • The surface features of karst landscapes often result in unique challenges for human activities such as agriculture, construction, and water management.
  • Sinkholes can pose risks to infrastructure, and the dissolution of rock can impact the availability of surface water.

 

 

 

Landforms Formed by Glaciers

 

Feature	Description	Example Locations
Erosional Landforms
Cirques	Bowl-shaped depressions carved by glacial headwaters	Rocky Mountains, Alps, Himalayas
U-shaped valleys	Wide, deep valleys with steep sides created by valley glaciers	Yosemite National Park, Glacier National Park
Hanging valleys	Tributary valleys left high above the main valley due to glacial erosion	Norway, New Zealand
Fjords	Long, narrow inlets formed by glacial erosion and flooded by seawater	Norway, Alaska, Chile
Aretes	Sharp ridges formed by the erosion of opposing cirques	Alps, Scottish Highlands
Horns	Pyramidal peaks formed by the intersection of several cirques	Matterhorn, Mont Blanc
Roches moutonnées	Rounded bedrock knobs with a smooth upstream face and a steep downstream face	Scandinavia, Canada
Striations	Scratches and grooves on rock surfaces made by glacial abrasion	Yosemite National Park, Glacier National Park
Depositional Landforms
Moraines	Ridges of glacial debris deposited at the terminus or sides of a glacier	Alps, Himalayas, Rocky Mountains
Drumlins	Elongated, streamlined hills composed of glacial till	Great Lakes region, Ireland
Kames and eskers	Sand and gravel ridges deposited by meltwater streams	New England, Scandinavia
Outwash plains	Flat areas formed by the deposition of meltwater sediments	Iceland, Patagonia
Glacial lakes	Bodies of water formed by meltwater filling depressions left by glaciers	Canadian Rockies, Finland