Go through these RBSE Class 11 Geography Notes Chapter 8 Major Landforms contain important concepts so that students can score better marks in the exam.
Rajasthan Board RBSE Class 11 Geography Notes Chapter 8 Major Landforms
- The physical features of the external surface of the earth are called Relief. It includes the high and the low parts of the earth’s surface.
- The formation of different landforms of the earth’s crust is a result of the interactions between the internal and external forces of the earth.
- Adequate variation is found in the shape of various landforms that appear on the earth’s crust – continents, oceans, mountains, plateaus, plains, lakes, etc.
- Landforms are classified into three categories: First Order Relief, Second Order Relief and Third Order Relief.
- The continents and oceans are included in the First Order Relief. The mountains, plateaus and plains are included in the Second Order Relief. The valleys, delta, etc. are included in the Third Order Relief.
- Highly elevated part above the earth surface having a narrow peak and steep slope, such a landform is called the Mountain.
- The height of mountains varies according to their formation process, age, location, structure and texture.
Classification of Mountains
- Mountains found in the world are classified on the basis of their origin, height and age.
- On the basis of origin, the mountains are classified into-Folded Mountain, Dome-Shaped Mountain, Accumulated Mountain, Block Mountain and Residual Mountain.
- On the basis of height, the mountains are classified into High Mountains, Average High Mountains, Less High Mountains and Low Mountains.
- On the basis of age, the mountains are classified into-Permian Mountain, Caledonian Mountain, Hercynian Mountain and Alpine Mountain.
Effects of Mountains on Human Life
- Mountains are helpful for human life. They occupy an important place in terms of tourism, recreation, mountaineering, security and from strategic point of view.
- Rivers originate from the mountains by which the facilities of drinking water, irrigation, fisheries and hydro-electricity are available to people.
- Elevated part above the earth surface, whose top part is flat and broad, and the edges are with steep slope is called the Plateau.
- The height of plateaus is usually more than 300 meters above the sea-level.
Classification of Plateaus
- Plateaus are classified on the basis of their origin, location, climate and stage of development.
- On the basis of origin, the plateaus are classified into – Lava Made Plateau, Glacial Plateau, Air Made Plateau and Water Made Plateau.
- On the basis of location, the plateaus are classified into – Intermountain Plateau, Piedmont Plateau and Continental Plateau.
- On the basis of climate, the plateaus are classified into-Humid Plateau, Arid Plateau and Snowy Plateau.
- On the basis of stage of development, the plateaus are classified into-New Plateau, Mature Plateau, Old Plateau and Rejuvenated Plateau.
Importance of Plateau
- Fertile soil is formed from plateaus. In addition of being the store-house of many minerals, they are also an ideal place in the formation of water bodies and reservoirs.
- The surface terrain with low relief and relatively flat, regular and gradual slope is called the Plain.
- Plains are the most favourable for human habitation.
Classification of Plains
- On the basis of the formation-process, plains are classified into two parts – Erosional Plain and Depositional Plain.
- Erosional plains are further classified into-River Eroded Plains, Glaciated Plains, Wind Eroded Plains and Karst Plains.
- Depositional plains are further classified into-River Deposited Plains, Glacio-Fluvial Plains, Loess Plains, Lava-Made Plains and Lake-Made Plains.
Importance of Plains
- Plains are the best place for population inhabitation, development of civilizations, pasture, development of transportation, construction of canals, etc.
- Dense population of the world is found in the plains.
- An elongated depression of the earth’s surface usually between the ranges of hills or mountains which is created by tectonic events or external forces.
- Valleys are formed by rivers, by surface deformation, by underground water and by glaciers.
Classification of Valleys
- Valleys are classified on the basis of their formation by tectonic events, formation by external forces, on genetic basis, on basis of their condition, as per the direction of structure and base changes.
- Valleys formed by tectonic events are classified into Synclinal Valley and Rift Valley.
- Valleys formed by external forces are classified into River Valley, Glacial Valley and Blind Valley.
- On genetic basis, the valleys are divided into Consequent Valley, Subsequent Valley, Obsequent Valley, Resequent Valley and Insequent Valley.
- On the basis of condition, the valleys are classified into Youth Valley, Mature Valley and Old Valley.
- As per the direction of structure, the valleys are classified into Ansequent Valley and Superimposed Valley. As per the base changes, the valleys are classified into Drowned Valley and Rejuvenated Valley.
Concept of Landform Development
- Continents and oceans are the largest landforms on the earth’s surface, which are called the First Order Landforms.
- Mountains, plateaus and plains are the Second Order Landforms, while the topographies formed by external forces are the Third Order Landforms.
- The creation of landforms is caused by endogenetic forces, while their destruction is caused by exogenetie forces.
- Concept of geo-plate tectonics helps in gaining information about mountainization, earthquake, volcano and Continental Drift.
- The concepts of geomorphic cycle and erosion cycle solve the problems related to the development of the Third Order Landforms.
Major Landforms Notes Important Terms
→ First Order Relief: Continents and oceans found on the earth are called the First Order Relief.
→ Second Order Relief: Mountains, plateaus and plains found in the continents and oceans are called the Second Order Relief.
→ Third Order Relief: The landforms formed by the process of denudation are called the Third Order Relief.
→ Delta: A delta is an area of low, flat land shaped like a triangle, where a river splits and spreads out into several branches before entering the sea.
→ Endogenetic Force: The force coming from within the earth and causing horizontal and vertical movements are known as endogenetic force.
→ Exogenetic Force: The force forming or occurring on the surface of the earth which are always active in levelling the earth’s surface.
→ Compression: The force falling in opposite direction on any area or substance thereby making the folds in it.
→ Diastrophism: Slow and long-term earth’s movements originated from the internal forces of the earth, which cause deformation on the earth’s crust at a large scale and form huge-sized landforms like oceans, mountains, etc.
→ Epeirogenetic Force: Change in the continental part due to diastrophism.
→ Orogenetic Force: The force responsible for the formation of mountains which is originated due to diastrophism.
→ Anticline: Due to the process of compression, when the rocks take a curved form, then an upward curved fold in the layers of rocks in the earth’s surface is called Anticline.
→ Syncline: Due to the process of compression, when the rocks take a curved form, then a downward and U-shaped fold in the layers of rocks in the earth’s surface is called Syncline.
→ Fossil: The remains or impression of a prehistoric plant or animal embedded in rock and preserved in petrified form.
→ Dome-Shaped Mountain: When mass-land rises to a higher altitude in the shape of an arc due to strong geological force, then the dome-shaped mountains are formed.
→ Accumulated Mountain: Mountains which are formed by the deposition of volcanic substances and the materials carried by air, rivers, glaciers and sea waves.
→ Block Mountain: The mountain or highland formed due to the downward displacement of landmass between two parallel faults.
→ Relict / Residual Mountain: The mountain or landform which is reduced to more low and flat peak due to denudation process.
→ Denudation: The combined form of the weathering and erosion processes is called Denudation.
→ Tour: The journey conducted with the objective of recreation, income, voyage, business, education, health-benefits, inspection, etc.
→ Irrigation: Artificial arrangement of supplying water to the fields for the growing and production of crops in dry season.
→ Geosyncline: A usually elongated, basin like depression along the edge of a continent, in which a thick sequence of sediments and volcanic deposits accumulates.
→ Intermountain Plateau: Plateau located between the mountains and surrounded by them.
→ Piedmont Plateau: Plateau located on the foot of any mountain is called the Piedmont Plateau. This type of plateau is located at high mountains, plains or in middle of the ocean.
→ Continental Plateau: A vast plateau on the large terrain of a continent on whose borders usually the plain or sea-coast is located, but mountain ranges can also be there at any of its side.
→ Evaporation: A process by which a substance is converted from the liquid to the state of vapour.
→ Escarpment or Scarp: An escarpment is a wide and steep slope on a hill or mountain.
→ Bad-Land: Rough and uneven landform formed on the earth’s surface.
→ Ridge: A long, narrow hilltop, mountain range, or watershed. Ridge located in ocean is called the oceanic-ridge.
→ Monadnock: A residual hill that consists of hard rock rising above a pedeplain in an area formed in the last stage of the cycle of erosion of a landmass.
→ Mechanical Weathering: The action of disintegration in the rocks by physical factors like sunlight, snow, wind, water etc.
→ Corrosion: A type of erosion action in which pebbles, stones, boulders, rock particles, etc. along with any factor of erosion erode the land-surface by rubbing or scraping.
→ Pediplain: Flat surface with extreme gentle slope formed by many sediments found in the last stage of the cycle of erosion in semi-arid region and which has a thin layer of debris on it.
→ Karst Plain: In the region of lime-rocks, when the surface unevenness ends in the last stage of the cycle of erosion of underground water, the Karst Plain is formed.
→ Piedmont Plain: Plain formed by the solidification of sediments coming from the height in the foothills of mountain.
→ Glacio/Fluvial Plain: Plain formed by the deposition made by glaciers.
→ Snow Line: The boundary marking the lowest altitude at which a given area, such as the top of a mountain, is always covered with snow.
→ Loess Plain: Plain formed by the regular deposition of dust by the air.
→ Synclinal Valley: Curved folds occurred in rocks due to the compression force of tectonics action, which causes anticline and syncline. Synclinal valley is formed in subsided part of the folding.
→ Rift Valley: A steep-sided valley formed by the downward displacement of a block of the earth’s surface between two nearly parallel faults.
→ Hanging Valley: A valley that opens at one end to another valley below, having a cliff or steep wall below the point where they meet.
→ Blind Valley: A valley, commonly in karst, that ends abruptly downstream at the point at which its stream disappears Underground.
→ Dip: Dip is the acute angle that a rock surface makes with a horizontal plane.
→ Consequent Valley: The valley formed by the initial streams that originate in a particular region in accordance with the initial slope of the land.
→ Subsequent Valley: The valley formed by streams originated after the consequent stream and joining the master consequent at right angles.
→ Old Valley: This is the last stage of valley. The slope of valley gets extremely gentle in this stage and valley starts becoming flat.
→ Ansequent Valley: In the valley developed before the uplift of a landmass, even after the uplift of the land, the river flows in pre-built valley, then it is called Ansequent Valley.
→ Superimposed Valley: When the valley formed on the upper layers of surface follows the same direction on the lower hard layers of rocks, then it is called Superimposed Valley.
→ Drowned Valley: A submerged coastal valley formed as a result of rise in water level of a ocean or lake or sinking down of proximal place is called Drowned Valley.
→ Rejuvenated Valley: On the fall in sea level, river rejuvenation involves a renewed period of vertical erosion to achieve a new and lower base level, which is called Rejuvenated Valley.
→ Tethys Sea: Large aquatic part extended between the ancient Angaraland and Gondwana land landmasses is called Tethys Sea.
→ Plate: The hard segment of the surface which can float across on heavy semi-molten rock.
→ Continental Drift Theory: The concept according to which the present form of the continents has been attained as a result of the movement of large landmasses.