A landform is a feature on the Earth’s surface that is part of the terrain. Endogenic forces and exogenic forces can create a lot of landforms. Mountains, hills, plateaus, and plains are the four major types of landforms. Minor landforms include buttes, canyons, valleys, and basins.
Mountains Landforms
A mountain is a significant landforms that, in a constrained region, rises above the surrounding land, typically in the form of a peak. A mountain often has a steeper slope than a hill.
Mountains are created by volcanism or tectonic causes. Locally, these pressures may increase the earth’s surface.
Mountains gradually erode as a result of the activity of rivers, weather, and glaciers. While some mountains have isolated summits, the majority are part of vast mountain ranges.
Mountains cover over 27% of the earth’s land area.
Up to 80% of the fresh surface water in the world comes from the mountains.
According to the UN’s Food and Agriculture Organization (FAO), about 12% of the world’s population lives in the mountains, but over 50% are directly or indirectly dependent on mountain resources.
The mountains, on the basis of their mode of formation, can be classified as:
- Fold Mountains
- Block Mountains
- Volcanic Mountains/ Accumulated Mountains
- Residual Mountains/ Relict Mountains
1. Fold Mountains
The earth’s crust develops huge fold-like structures as a result of the compression of tectonic plates, which results in the formation of fold mountains.
The majority of the well-known mountain ranges on earth are examples of Fold Mountains, which are primarily found as mountain ranges.
Characteristics of fold mountains
The formation of the mountains is one feature that all fold mountains share. The formation of all fold mountains results from the collision of various tectonic plates along a convergent boundary, which distorts the earth’s crust.
Another feature of Fold Mountains is its arcuate shape, where the length of the mountains is significantly greater than the width.
Fold Mountains are the result of intense pressure being applied to rock strata, which metamorphosizes the layers of rock.
Fold Mountains are based on their location as these mountains are predominantly situated along the margins of continents with the margins being close to oceans.
All fold mountains also feature the shape of an arc where one slope is concave-shaped while the other slope is convex shaped.
Formation of fold mountains
When two continental tectonic plates move toward one another and collide at the destructive plate boundary, which is also known as the convergent boundary, mountain ranges are created. The earth’s crust is bent by the immense strain the rocks are under, creating folds similar to those on a piece of cloth but on a far larger scale. In areas of the crust where the crust has a weak layer, such as one formed of salt, the folding effect is more pronounced.
Types of fold mountains
There are several thresholds used to distinguish different types of Fold Mountains.
Age: Fold mountains are classified into young fold mountains (aged between 10 and 15 million years) and old fold mountains (aged 200 million years and above).
Geography of the mountains: There are either simple fold mountains or complex fold mountains. In simple fold mountains, the synclines and anticlines are well developed creating a wave-like appearance to the mountains while in complex fold mountains, the compression forces cause the formation of a very complex structure known as the nappe.
Examples of fold mountains
- Himalayas in Asia,
- Andes Mountains in South America
- Aravalli in Asia (Old Fold Mountains )
2. Block Mountains
When two continental tectonic plates move toward one another and collide at the destructive plate boundary, which is also known as the convergent boundary, mountain ranges are created. The earth’s crust is bent by the immense strain the rocks are under, creating folds similar to those on a piece of cloth but on a far larger scale. In areas of the crust where the crust has a weak layer, such as one formed of salt, the folding effect is more pronounced.
Characteristics of block mountains:
- Block mountains have flat tops or slightly sloping surfaces.
- They have steep sides and they are associated with rift valleys.
- It is a block between two fluids.
- It has fairly steep, straight edges.
- Block Mountains are usually high. Examples of block Mountains include Voges Mountain and the Black Forest of the Rhine land.
3. Volcanic Mountains
Volcanoes create volcanic mountains, as the name implies. Magma, which is molten rock that is found deep under the ground, erupts and builds up on the surface to produce volcanic mountains. When magma penetrates the earth’s crust, it becomes lava. The ash and lava solidify into a rock cone as they cool. Layers of rock and lava build up on top of one another.
Characteristics of volcanic mountains:
Eruption: Occurs when a volcanic mountain becomes active and ejects lava, ashes, and chemical gases.
Explosion: An explosion occurs when a volcanic mountain explodes, sending thrusts of boulders, broken stratoplates, molten magma, and bombs into the atmosphere. This produces high heat, red hot lava with a mixture of hot water, and dense smoke causing the combustion of mixed clouds, debris, and ash.
Expansion: Occurs when the ground surface of a volcanic mountain expands as a result of molten magma, split stratoplates, intense heat, and debris causing the cooling of rushing lava to form hardened magmalike. The temperature of a volcanic explosion can reach 600oC, which is extremely high. These types of expanded landforms regions are typical of Hawaii.
Uplift or Inflation: a bulge or uplift on the surface is caused when a mass of fresh lava comes to the surface and pushes older rock aside and upward. The growth of a volcano caused by the lava pushing up inside is comparable to inflating a balloon by breathing fresh air into it, which is why the process is frequently referred to as inflation. A number of techniques are used to gauge a volcano’s inflation, including tilt meters that gauge the angle of the ground surface, laser ranging that makes use of mirrors set up on the mountain, and precise aerial photography surveys.
Emulsification: occurs when a volcano becomes active, ejecting molten lava mixed with chemical fumes and producing aqueous fluids with higher oil content. The layers of the landforms that are ready to be drilled and exported contain these emulsion fluids contained within very cold layers. By delicately separating the phases of immiscible liquids, such as oil and water, an emulsion is created that is momentarily stable. Water suspended in oil (w/o) or oil suspended in water (o/w) are two common types of emulsions. More intricate systems, such as oil in water in oil (o/w/o), can also exist. In situations like this, filtering the oil from the combined water is then processed to remove the water.
Craters: A bowl-shaped depression formed by a volcanic eruption or impact of a meteorite.
Types of volcanic mountains:
Cinder cone mountains are made up of material blasted out that rains back down. They don’t usually grow too large.
Shield volcanoes are built up by many lava flows of low viscosity lava (low viscosity means that it flows more easily). The lava can flow for dozens of kilometers, and the volcano can be very wide.
A stratovolcano or composite volcano is made up of many layers of ash, rock, and hardened lava. Some of the largest, most impressive volcanoes in the world are stratovolcanoes.
Examples of volcanic mountains:
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- Krakatau, Indonesia – The entire island was obliterated by its 1883 eruption, and sunsets around the world changed color for the next two years.
- Lassen Peak, California, USA – erupted in 1917, beginning a period of nearly 75 eruption-free years in the 48 contiguous states.
- Llullaillaco, Argentina/Chile – At more than 22,000 ft, the world’s highest active volcano last erupted in 1877.
- Mauna Loa, Hawaii, USA – This is the world’s largest active volcano. Its most recent eruption was in 1984.
- Mt. Fuji, Japan – This famous symbol of Japan last erupted in 1707.
- Mt. Mazama, Oregon, USA – Crater Lake formed 7,000 years ago when its side blew out and the top collapsed.
- Mt. Pelee, Martinique – In 1902 only two of the 30,000 inhabitants of the adjacent town survived its 1902 blast.
- Mt. St. Helens, Washington, USA – It gave several days’ warning before erupting in 1980, yet 57 people ignored experts’ advice to relocate and lost their lives.
- Mt. Tambora, Indonesia – The ashes from its 1815 eruption blocked the sun through most of 1816, creating a ―year without summer.‖
- Mt. Vesuvius, Italy – The city of Pompeii was buried under its eruption in the year 79.
4. Residual Mountains
Residual mountains are those mountains that have been eroded by the agents of degradation such as winds, rain, frost, and running water. The hard rocks that are left behind are called residual mountains.
Formation of residual mountains:
Residual mountains are formed from already existing mountains that are lowered or reduced by agents of denudation such as Running water, ice, and wind, Residual mountains are therefore the remains of already existing mountains.
Some hard, and very resistant parts of the existing mountains remain after the lowering of the upper part. This remaining part is called the Residual Mountains which are also Mountains of Denudation.
The Aravalli Mountain and the Parasnath mountain of Bihar belong to this type.
Examples of residual mountains:
- The Nilgiris
- The Parasnath
- The Rajmahal
- The Aravalis
Economic Significance of Mountains
- A storehouse of resources: Mountains are the storehouse of natural resources. Large resources of minerals like petroleum, coal, and limestone are found in mountains. The mountains are the main source of timber, lac, medical herbs, etc.
- Generation of hydroelectricity: Hydroelectricity is mainly generated from the waters of perennial rivers in the mountains.
- An abundant source of water: Perennial rivers arising in the snow-fed or heavily rain-fed mountains are one of the important sources of water. They help in promoting irrigation and provide water for many other purposes.
- Formation of fertile plains: The rivers that originate from the high mountain ranges bring silt along with water to the lower valleys. This helps in the formation of fertile plains and further the expansion of agriculture and related activities.
- Natural political frontiers: The mountains can also act as natural boundaries between the two countries. They have a prominent role in protecting the country from external threats.
- Effects on climate: They serve as a climatic divide between two adjoining regions. The mountains cause orogenic rainfalls, diversion, and blocking of cold winds, etc.
- Tourist centers: The pleasant climate and beautiful sceneries of the mountains have led to their development as centers of tourist attraction.
Plateaus Landforms
A plateau is a piece of land with a flat top. Every continent has plateaus, which occupy one-third of the surface of Earth. Together with hills, mountains, and plains, they make up one of the four main types of land. Like mountains, plateaus can be young or old. One of the oldest plateaus is in India’s Deccan region.
River water slashes through the plateau, creating valleys. The Columbia River passes through the Columbia Plateau, which is located in northwest America between the Cascade and Rocky mountains.
A plateau may occasionally be so degraded that it is divided into smaller elevated areas known as Rock formations that are extremely ancient and dense and make up several outlier plateaus. In plateau outliers, iron ore and coal are frequently discovered. Plateaus are very useful because they are rich in mineral deposits. As a result, many of the mining areas in the world are located in the plateau areas.
On the basis of their geographical location and the structure of rocks, the plateaus can be classified as:
- Intermontane Plateaus,
- Piedmont plateaus,
- Continental plateaus,
- Volcanic plateaus,
- Dissected plateaus,
1. Intermontane Plateaus
The intermontane plateaus are those that border mountain ranges (often fold mountains) or that are completely or partially surrounded by them.
The definition of “intermontane” is “between mountains.”
The highest plateaus in the globe are intermontane.
They have almost horizontal rock layers that have been uplifted to extreme heights by the earth’s vertical movements.
Examples: The Himalayas, Karakoram, Kunlun, and Tien Shah are just a few examples of the fold mountains that surround the intermontane plains that make-up Tibet.
2. Piedmont Plateaus
A piedmont plateau is a plateau that is located at the base of a mountain and is enclosed on one side by a plain or by the sea or an ocean.
Piedmont is a word that means “foot of a mountain.”
Since the lands were formerly high to the level of mountains but have since been eroded down to the mountain’s foot level, they are also known as Plateaus of Denudation.
Examples: Piedmont plateaus include the Malwa Plateau.
3. Continental Plateaus
Either a significant continental upliftment or the total replacement of the old terrain by horizontal basic lava sheets (less viscous) is responsible for their formation.
In contrast to the neighboring plain or sea, this type of plateau displays an abrupt elevation (i.e. more steepness on the sides).
The Plateaus of Accumulation are another name for the Continental Plateaus.
Examples of continental plateaus include the Maharashtra Plateau.
Volcanic Plateaus
A volcanic plateau is created by multiple tiny volcanic eruptions that gradually accumulate over time, creating lava flows that eventually form a plateau.
Two examples of such plateaus are the Deccan Traps and the Columbia Plateau in the northwest of the United States of America.
There are two main types: Lava plateaus and Pyroclastic plateaus.
- Lava plateaus are formed by highly fluid basaltic lava during numerous successive eruptions through numerous vents without violent explosions.
- Pyroclastic volcanic plateaus are produced by massive pyroclastic flows and they are underlain by pyroclastic rocks.
Dissected Plateaus
A plateau that has been significantly eroded, resulting in sharp relief, is referred to as a dissected plateau. Such a region might seem hilly.
Dissected plateaus can be distinguished from orogenic mountain belts by the absence of orogeny’s accompanying folding, metamorphism, substantial faulting, or magmatic activity (mountain building).
Example: New York State’s Catskill Mountains.
The economic significance of Plateaus
A storehouse of minerals: Plateaus are where the majority of the world’s minerals are found. In comparison to mountains, plateaus make it easier to extract minerals. Plateaus provide the majority of the raw materials used in industry. We obtain gold from the plateaus of Western Australia, Africa, and India. The Chotta-Nagpur Plateau in India provides coal, iron, manganese, and mica.
Generation of hydel power: The edges of plateaus form waterfalls which provide ideal sites for generating hydel power.
Cool climate: The higher parts of the plateaus even in tropical and sub-tropical regions have a cool climate.
Animal rearing and agriculture: plateaus have large grassland areas suitable for animal rearing, especially sheep, goats, and cattle. The lava plateaus when compared to other plateaus are richer in minerals and hence used for agriculture as the soil is very fertile.
Plains Landforms
Any section of the Earth’s surface that is basically level and has only minor local relief in the form of gentle slopes Sizes of plains range widely.
The largest spans hundreds of thousands of square kilometers, such as the Great Plains of North America and the expanse of gently undulating land that stretches from the Pyrenees Range on the French-Spanish border across northern Europe and Asia almost halfway around the world nearly to the Bering Sea. The smallest only occupy a few hectares.
Plains are present on all continents with the exception of Antarctica, where they make up little more than one-third of the earth’s surface.
The majority of the plain was created by the deposition of river sediments. In addition to rivers, the wind, shifting glaciers, and tectonic activity have also contributed to the formation of some plains.
They can be found in the tropics, in the middle latitudes, and north of the Arctic circle. The world’s plains exhibit significant variance in vegetation in line with their wide geographic distribution.
Some are covered in trees, while others are grassland. Others maintain bunch grass and scrub brush, while others, which are deserts with almost little water, support only the most minimal and scarce plant life.
Types of Plains
1. Outwash Plain
A glacier-created outwash plain is sometimes known as a sandur. When a glacier deposits sediments near its terminus, a plain like this is created. A glacier transfers the sediments scraped from the bedrock downstream as it flows, eroding the bedrock. The glacier’s meltwater deposits these sediments at the snout.
In Iceland, outwash plains are a typical land shape. With a surface area of 1,300 square kilometers, Iceland’s Skeiarársandur is the largest outwash plain in the world.
2. Till Plain
A plain created by glacial activity is sometimes known as a till plain. These plains are created by glacial till deposition (unsorted glacial sediment). A till plain is created when a sheet of glacial ice separates from the main glacier and melts there while still in its original location.
These plains were produced by the Wisconsin glacier and can be seen in northern Ohio.
3. Lava Field
A lava field can also be referred to as a lava plain. Such a plain is formed by the accumulation of layers of lava. The lava plains can stretch for miles and are easily visible from the air or in satellite images where they appear darker in color than the surrounding landscape.
4. Lacustrine Plain
In places that were formerly covered by lakes, lacustrine plains develop. The sediments left behind on the lakebed when a lake completely empties out owing to elements like evaporation, natural drainage, etc. create a plain. Depending on the sedimentary makeup, such lacustrine plains could form a marsh, a desert, or even be extremely fertile and support agriculture. In Southern Indiana in the United States, laceustrine plains are widespread. These plains are discovered where proglacial lakes once existed.
Another illustration of a lacustrine plain is the Indian Kashmir Valley.
5. Scroll Plain
Scroll plains are formed in areas where a river meanders across a low gradient. Deposition of sediments at such locations results in the formation of a plain. Oxbow lakes are common occurrences in such areas.
In New Zealand, the Taieri River creates a stunning scroll plain close to Paerau.
6. Flood Plain
A plain that runs from the banks of a river or stream to the surrounding valley walls is referred to as a floodplain. Flooding typically occurs in floodplains when the nearby water body overflows. The plains are made up of floodwater-deposited silts, sands, levees, and other materials and are frequently fruitful. Floodplains typically have a diverse environment. These plains are home to numerous cities with substantial populations. However, a lot of the worst floods in recorded history have happened in floodplains.
The Yellow River’s floodplains are one such area that is frequently subjected to deadly floods.
7. Alluvial Plain
Massive, sweeping lengths of plain land known as alluvial plains are created by the accumulation of alluvial sediments. Floodplains are typically part of an alluvial plain, but they can spread beyond these plains. The pattern of floodplain movement throughout geological time is represented by an alluvial plain. Erosion-related sediments are carried by rivers as they flow down mountains or hills and are transported to the lower plain. The elevation of the floodplain rises with time as sediments accumulate, while the width of the river channel narrows. The river now searches for a different route with a higher channel capacity because it can no longer handle the pressure. Thus, the river forms a meander and flows through a new channel. In this way, floodplains continue growing and adding up to form massive stretches of alluvial plains. The Indo-Gangetic Plain in India and the Po Valley in Italy are examples of alluvial plains.
8. Abyssal Plain
Abyssal plains are found on the ocean floor at extremely deep depths. These plains can be found between 9,800 and 20,000 feet below the surface. Approximately 50% of our planet’s surface is made up of abyssal plains.
These landscapes are among the flattest and smoothest in the globe, as well as some of the least explored. The abyssal plains cover a vast area. The Sohm Plain in the North Atlantic Ocean, for instance, has a surface size of around 900,000 square kilometers.
While extremely uncommon in the Pacific Ocean, such plains are more prevalent in the Atlantic Ocean. These plains are thought to have developed as a result of sediments from the land depositing in the abyssal depressions. Such deposition occurs in many layers till the underlying irregular features are smoothened out to result in a flat Plain.
The economic significance of Plains
- Fertile soil: The plains generally have deep and fertile soil. As they have a flat surface, the means of irrigation can be easily developed. That is why plains are called the ‘Food baskets of the world’.
- The growth of industries: The rich agricultural resources, especially of alluvial plains, have helped in the growth of agro-based industries. Since the plains are thickly populated, plenty of labor is available for intense cultivation and for supplying the workforce for the industries.
- Expansion of means of transportation: The flat surface of plains favors the building of roads, airports, and the laying down of railway lines.
- Centers of civilizations: Plains are centers of many civilizations.
- Setting up of cities and towns: Easy means of transportation on land and the growth of agriculture and industries in plains have resulted in the setting up and expansion of cities and towns. The most developed trade centers and ports of the world are found in the plains only and as much as 80% of the world’s population lives here.
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