Earth’s
landforms are one of the major topics of various Government exams.
The following article covers important points about the four major types of
landforms on Earth. This article is brought to you by Oliveboard, an online
exam preparation platform for government and banking exams.
What
are Landforms?
Landforms
are topographic features on the surface of earth formed by processes
such as volcanic activities, movement of tectonic plates, sediment
deposition, water and wind erosion.
The
highest landform on Earth is the Mount Everest, which measures at 8,850
meters above the sea level and the deepest landform is the Mariana
Trench (in the Pacific Ocean), which is approximately 10,916 meters deep.
Four
major types of landforms on earth:
- Mountains
- Hills
- Plateaus
- Plains
Mountains
Mountains
are landforms that prominently stretch above their surrounding land in a
limited area. They’re usually in form of a peak and exhibit slopes that are
steep. Mountains are usually formed due to volcanic/tectonic
activities(movement of plates under the Earth).
Mountains
rarely occur individually, they’re usually part of elongated chains. When
a series of such chains are linked together, they constitute a mountain
belt.
Mountains
erode over time, through glaciers, rivers and weather conditions. Mountains
usually aren’t used for agriculture, since the climate and topography aren’t
hospitable for it. Mountains are mostly used for recreational purposes such
as mountaineering and for extraction.
Hills
Hills
are lands that rise high above the surrounding area (like a bump on the surface
of Earth). But unlike mountains, hills usually do not have steep slopes,
and often have distinct summits. Hills are usually shorter than mountains,
and are easier to climb. Some geographers in the past considered mountains as
hills that have heights greater than 1,000 ft (above sea level). However, this
theory was discarded.
Hills
are formed through natural geological activities. One such activity is
called ‘Faulting’. Faulting happens due to the constant movements of rocks
underneath the Earth’s surface, which results in shift in the landscapes.
Sometimes, hills that are formed by faulting become mountains. For instance,
the Himalayas.
Other
processes that form hills are erosion caused by rivers, when bits of sediments,
soil and rocks get washed away by them and pile up at some other place.
Plateaus
Plateaus
are elevated, flat highland areas that rise significantly above the surrounding
area, with one of more sides having steep slopes. Plateaus are
remarkably flatter. Some of them are part of mountain belts. Plateaus take
up almost 1/3rd of the Earth’s surface and are present on every
continent. The highest and the largest plateau is the Tibetan Plateau,
which is in Asia.
Plateaus
are formed by a number of natural processes such as erosion caused
by water and glaciers, upwelling of magma or extrusion of lava. Most
plateaus have a hard-durable surface called the caprock, formed due to
erosion of soft rock. Caprocks protect the soil underneath the plateau from
getting eroded.
When
river water cuts through plateaus, they form valleys, like the Columbia
plateau, which is cut through by River Columbia.
Plains
Plain
is a board and relatively flat landform, that sweep over a large area of
land. Plains cover more than 1/3rd of Earth’s land area. Plains
occur on land as well as under the ocean, as coastal plains, plateaus, along
valleys or on doorsteps of mountains.
Plains,
like mountains, hills and plateaus, are formed by various natural
processes. Some are formed when water/ice erode away rocks/dirt (sediment) down
hillsides and deposit it elsewhere. Plains are formed when layer upon layer of
sediment is laid down this way. Other activities that form plain lands
are volcanic activities, flow of lava and movement of rivers.
Types
and Characteristics of Major Landforms:
Mountains
Mountain
landforms cover approximately 1/5th of the Earth’s surface.
Around 80% of world’s fresh water comes from the mountains. The characteristics
of Mountain landforms vary depending on their location, altitude, biomes and
the body of water that surrounds them, and their distance from the equator.
There
are a few features which are common in all mountains:
·
Higher elevation than the surrounding areas
·
Have steep slopes, sharp/rounded ridges and a peak/summit
·
They’re formed by volcanic or tectonic activities
·
High relief within the mountain ranges
Mountain landforms experience
higher precipitation than other ecosystems. The weather on mountains varies
according to the location and altitude. The weather on mountains is also highly
unpredictable and can change drastically within minutes at some places. One
minute it’s a clear sky and the next minute it’s a thunderstorm. Temperatures
can fall below zero degrees within minutes. Mountains are always under the
threat of wide range of natural disasters, erosion, and lava flows.
Despite
its unpredictable weather, mountains have great biodiversity and are home to
thousands of species of animals and plants. Due to the sensitive living
conditions on mountains, there is a large number of plants and animals that are
endangered. Around 10% of the world’s human population too live on the
mountains.
Types
of mountains
Volcanic
mountains: Volcanic
mountains are formed when molten rocks from inside the Earth’s crust erupt and
get piled up. Examples of volcanic mountains are, Mount Fuji in Japan and Mount
St. Helens in Washington State.
Dome
mountains: Dome
mountains are formed when the magma merely pushes Earth’s crust up and hardens
inside the crust, before erupting out of the surface. Rains and wind strike the
domes, and sculpt valleys and summits. Popular examples are, the Black hills of
South Dakota and Adriondack mountains of New York.
Plateau
mountains: Formation
of plateau mountains is similar to that of Dome mountains, except that, plateau
mountains are formed due to tectonic activities, when tectonic plates push up
the crust without faulting/folding. Plateau mountains are then shaped by
erosion and weathering processes.
Fault-block
mountains: These
also occur due to tectonic activities. Fault-block mountains are formed when
there is stress between tectonic plates. This leads to cracking of the surface
of Earth, forcing the rocks up and down. Examples of fault-block mountains are,
Sierra Nevada and Harz.
Hills
Hills
have been homes to hundreds of people in rural as well as urban areas for
hundreds and thousands of years. A lot of people build their homes on hills to
avoid floods and defend themselves, for instance, the Ancient Rome.
Types
of Hills
Drumlin: Drumlins are elongated
hills (they look like an inverted spoon) formed by the movement of glacial ice
on the underlying till. Drumlins occur in different sizes and shapes
(parabolic, symmetric, etc.) and are typically 1 – 2 kms in length. They’re less
than 50 meters high and are 300-600 meters wide and are mostly composed of
glacial till, gravel and sand in varying proportions.Drumlins form near
glaciers/ice sheets and have most of glacially-formed features (scours, eskers,
valleys).
Tor: Tors (castle koppies/kopjes)
refer to the rock formation on top of hills or sometimes referred to the hill
itself. These are free standing rocks, that rise on smooth surroundings. Tors
are created by erosion/weathering of rocks like granites, dacites, dolerites,
coarse sandstones, etc. and are mostly 5 meters high.
Puy: Puys are volcanic hills
that are cone-shaped. Puys are also called as cinder cones and may or may not
be associated with lava. They’re found in clusters or lines or sometimes
isolated and scattered.
Pingo: Pingos are periglacial
(or non-glacial) mounds of earth-covered ice, that are mostly found in
Antarctica and Arctic & Subarctic regions. Pingos can reach up to a
diameter of 600 meters and heights of up to 70 meters.
Plateaus
Plateaus
have high flat surfaces which stretch for thousands of kilometers. Plateaus
that are eroded by the flow of rivers are among the most uniform in terms of
elevations, though their surfaces can be interrupted by canyons. Plateaus are
formed by crustal shortening/volcanic activities/thermal expansion (of the
lithosphere) and are found on most of the continents.
Erosion
influences the shapes of plateaus in drastic ways. When the erosion is heavy,
the plateaus are broken up into smaller raised landforms called as outliers, that
are composed of old and dense rock formations. Outliers contain iron ore and
coal.
Plateaus
are broadly of two types:Dissected
and Volcanic plateaus.
Dissected
Plateaus: Dissected
plateaus are formed when tectonic plates collide slowly, resulting in an upward
movement on the earth’s crust. A popular example is the Colorado Plateau
(Western US) which has been rising 0.3 centimeters a year since 10 million
years.
Volcanic
Plateaus: Volcanic
Plateaus are formed by lava that flows out of small volcanoes that slowly build
up over time and form plateaus. For instance, the North Island Volcanic Plateau
(Central part of North Island in New Zealand).
Intermontane
plateaus: Intermontane
plateaus are the highest plateaus in the world and are surrounded by mountains.
The Tibetan plateau is the highest intermontane plateau.
Piedmont
plateaus: Piedmont
plateaus are plateaus that have mountains on one side and a sea/plain on the other.
Popular examples are: Malwa Plateau, Patagonian plateau, etc.
Continental
plateaus: These
are vast plateaus that are surrounded on all sides by oceans/plains.
Continental plateaus form away from the mountains. Example: Antarctic plateaus,
Polar plateau, etc.
Plains
Grasslands: Grasslands are vast
stretches of plain regions, with grass as the primary type of vegetation. The
great plains, that are found across most of Central North America, are
grasslands.
Prairies: Prairies are temperate
grasslands, found in North America. Prairies can grow up to 1.5 meters high
depending on the weather. Tall prairies are plowed under and aren’t usually
farmland or pasture.
Steppes: Steppes are temperate
grasslands of Eastern Europe and Asia. These areas do not receive enough
rainfall to grow tall grass or trees.
Savannas: These are tropical
grasslands, which exist in places with warm temperatures throughout the year.
Savannas often have scattered trees and stretch across much of Central Africa
and are also found in Australia and South America and some parts of the North
America.
Not
all the plains are grasslands. There are some plains that are forested (like
the tabasco plain of Mexico). These have diverse types of vegetation, like
trees and shrubs. Parts of the Sahara desert are plains. The Arctic areas also
have plains and they’re called Tundra. Tundra are plains where the ground is
frozen. Tundras, despite being cold, are home to a lot of plants, including
moss and shrubs.
Types
of plains
Flood
plains: Flood
plains, as the name suggests, are formed when sand, sediment and mud carried by
floods pile up on land. Due to this reason, flood plains are extremely rich in
nutrients and create a fertile land for farming. One of the most popular
examples of flood plains, is the flood plain surrounding the Nile River of
Africa, which has helped Egyptian civilization to thrive for centuries.
Alluvial
plains: These
plains form at the base of mountains; they’re formed when water carrying rocks
and sediments flows downhill till it hits the flatland. The sediment is
deposited on that plain (in the shape of a fan). One of the popular examples is
the Huang He River in China, which has created an alluvial plain which
stretches for kilometers. The Huang He River is also called as the Yellow River
because of the yellow colored sediment it carries.
Coastal
plains: When
rivers carry sediment, and dump the sediment in the ocean, it builds up and
eventually rises above the sea level, forming a coastal plain. These plains
slope gently under water.
Abyssal
plains: Abyssal
plains are plains found at the bottom of all the oceans. These are
approximately 5000-7000 meters below the sea level. Abyssal plains are
considered as the flattest and smoothest surfaces on earth.
