SSC MTS Exam

Study Ma te r i a l f o r Genral Awareness

LANDFORMS

The landforms created as a result of erosion or deposition of running water, wind, glacier andmarine water.

Fluvial Landforms● These landforms are created as a result of erosion, transportation and deposition of running

water.

● American geomorphologist William Morris Davis propounded normal cycle of erosion byrunning water and stream in 1989.

● Running water is the most widespread and most significant geomorphic agent.

● The place of origin of the river is known as its Source. The place where it joins a lake or seaor an ocean is known as the river mouth.

● Falling of river water over a vertical step in the river bed is called waterfall.

● V-shaped valley – At youth stage kinetic energy of river is very high therefore erosion ispredominant over deposition, started vertical cutting, both the valley floor thus wateralways touches the valley sides; formed V-shaped valley or Gorge. For example – Indus gorgenear Bunji/Chilas, Brahmaputra gorge near Namcha Barva (Yangyoup pass).

● I-shaped valley – The V-shaped valley are gradually widened due to lateral erosion (erosionin horizontal direction) at base formed I-shaped valley or Canyons. For example – Grandcanyon of the Colorado river (USA).

● River Valley – The river flowing down with a steep gradient on the ground known as rivervalley.

● Waterfalls – When natural running water fall from some heights, it is known as the waterfall.For example:

o Tallest waterfall of the world – Angel (formed by Cairo River at Venezuela).

o Tallest waterfall of India – Kuchikal (formed by Varahi river at Karnataka) and Jog orGersoppa or Mahatma Gandhi (formed by river Sharavati at Karnataka).

o Widest waterfall of the world – Niagra between Erie and Ontario Lake at the borderof Canada and USA)

o Widest waterfall of India – Chitrakot formed by river Indravarti – Chhattisgarh).

● Pot Holes – They are found in the upper course of a river where it has enough potentialenergy to erode vertically to form kettle like small depression in the rocky beds whichgradually enlarge in both diameter and depth by swirling of grained rocks such assandstones and granites.

● Rills – A rill is a shallow channel cut into soil by the erosive action of running water.

● Gulley – Many micro rills merge together to form larger incised channels known as Gullies.

● Rapids – Small seasonal waterfalls are known as rapids.

● Peneplain – The penultimate end of normal cycle of erosion, which characterized byundulation surface with residual convexo concave low hills (Monanocks).

● Meanders – It is a bend or curve or loop in the course of a river channel. Each bend of amenders belt has two types of slopes.

o Concave slope – This is the slope where river channel strikes the valley side directlyforming a vertical cliffs.

o Convex slope – It is characterized by gentle slope which is formed by the depositionof sand, gravels and Alluvium.

● Oxbow lake – When curvature of menders loop is accentuated due to erosion in horizontaldirection to such an extent that menders loop come close enough to abandoned from themain channels to form OX-bow lakes. E.g. – Wular lake by river Jhelum.

● Alluvial cones and Alluvial fans – In the foothill areas when stream leaves the mountainsand comes down to the plain, the velocity of the stream decreases due to an abrupt drop inthe channel gradient, it sheds a lot of material in the form of cones known as Alluvial cones.Many Alluvial cones combine to form alluvial fans and many alluvial fans combine to formBhabhar planes.

● Natural Levees – These are narrow ridges of lows heights on both sides of a river whichprotect against floods. If natural levees cause sudden floods in adjoining area it is known asbreach.

● Flood plains – An area of flat land near a river that is often flooded when the river becomestoo full (overflow of water outside the bank known as flood).

● Delta – Term delta was first used by Herodotus (485 – 425 BCE); It is triangular shapedepositional features at the mouth of a river debouching either in a lake or sea. Types ofDeltas are as follows:

o Arcuate – It is general fan shaped profile formed by distributaries eg : Indus, Ganga,Nile, Tiber, Niger, etc.

o Bird food Delta – When limestone sediments deposited by distributaries in a birdsfoot like structures. For eg. – Mississippi

o Estuaries – When the mouth of the river appears to be submerged fresh water andsaline water get mixed, known as Estuaries. For example – Narmada, Tapti, Hugli etc.

● Balson – The intermundane in dry region is known as balson’s.

● Playas – Temporary saline lake in balson is known as playas.

● Salins – When salinity of playas increases due to evaporation of water it is known as salins.

● Bajada – The moderately sloping deposition plane near playa.

Aeolian Landforms

● According to Koppen, landforms formed by erosion and deposition by wind is known asaeolian landforms in which terminal fall velocity and threshold velocity of wind are involvedin the following ways – deflation, abrasion and attrition.

● Threshold velocity can be defined as the velocity required to displace a particle of aparticular size, larger the particle the higher the threshold velocity required to move it.

● Terminal velocity can be defined as the velocity at which a particle being transported anddeposited on the ground surface.

● Deflation is the process of lifting, carrying away dry, unsorted dust particle by winds.

● Abrasion is the process by which sand grains carried by wind erodes the rocks by grindingagainst its walls.

● Attrition is the wearing and tearing of sand particles during transportation.

● Wind erosion of surface particles begins when air velocities reach about 4.5 meters perseconds.

The major landforms produced by wind erosion are as follows –

● Deflation Hollow – When the force of wind is concentrated on a particular spot, erosion cancarve out a pit known as deflation hollows.

● Pan – These are larger shallow depression (cover thousands of square kilometres) formed bywind erosion. For example – Qattara depression (Libyan Desert).

● Mushroom Rocks – If wind erodes naturally occurring rock to acquire a shape likemushrooms. It is also known as rock pedestal.

● Isenberg/Monadnock – It is an isolated hill, knob, ridge, outcrop or a small mountainformed by wind erosion that rises abruptly from virtual level of surrounding plain.

● Demoiselles – It is also known as tent rock, fairy chimney or earth pyramid or Hoodoos. It isthe rock pillar where a thick layer of relatively soft rock such as mudstone, is covered by athin layer of hard rock, such as well cemented sandstone, limestone or basalt.

● Zeugen – It is formed in desert area where alternating horizontal layer of hard and soft rocksoccur. The top layer of hard rock is jointed and has crocks. Weathering opens up the jointsdeepening them to reach the soft layer of rocks. Abrasion continues, furrows are formed andgradually widened. The hard rock from the ridge separating the forrows, create ridge furrowlandscape. The ridge is called Zeugen.

● Yardang – It is a sharp irregular ridge of sand rock lying parallel in the direction of prevailingwind in exposed desert region, formed by the wind erosion of adjacent material which is lessresistant.

● Stone Lattice – When holes are formed in the stone by the action of powerful wind is knownstone lattice.

● Wind window – When in stone lattice, holes are gradually widened to reach the other endof the rocks to create the effect of a window, it is known as wind window.

● Wind Bridge – It is formed when the holes of wind window are further widened to form archlike features.

● Sand Dunes – These are the heaps or mounds of sand in deserts generally their height variesfrom 1 to 20 meters but in some cases it is 5-6 km long and several hundred meters high.The major types of sand dunes are as follows:

o Barchans – It is crescent shaped dunes whose long axis is transverse to the dominantwind direction. Its windward side is convex whereas leeward side is concave andsteep.

o Transverse dunes – It is long asymmetrical dune that forms at a right angle to theprevailing wind direction.

o Parabolic dunes – These are U-shaped dunes whose long axis is transverse to thedominant wind direction. These are much longer and narrower than Barchans.

o Star dunes – These are large pyramidal or star shaped dunes with three or moresinuous radiating ridge from a central peak of sand. This dune has three or more slipfaces.

o Longitudinal dunes – These dunes are created when there are strong winds from atleast two directions. The dune ridge is symmetrical, aligned parallel to the netdirection of the wind and has slip faces on other side. These dunes are commonlyfound at Sahara, Australian, Libyan, Thar and south Africa desert.

o Reversing Dunes – Its ridge is asymmetrical and has two slip faces. It is intermediatebetween star and transverse dunes.

o Coastal Dunes – It forms when there is a large supply of beach sand and strong windblowing from sea to shore. The beach area must also be wide and sufficientlyinfluenced by wave action.

o Dome – Mound of sand that is circular or elliptical in shape. Has no slip faces. May beformed by the modification of stationary barchans.

Glacial Landforms

● A large body of ice moving slowly down a slope or valley due to gravity is called a glacier.Glaciers are grouped into Mountain or Valley Glaciers and Continental Glaciers.

● Continental Glacier: The glacier covering vast areas of a continent with thick ice sheets. E.g.,Antarctica, Greenland.

● Mountain or Valley Glacier is a stream of ice, flowing along a valley. It usually follows formerriver courses and is bounded by steep sides. E.g., the Himalayas and the Alps.

● According to their temperature regime glaciers are classified into two main types, temperateor Isothermal and polar or cold Glacier.

The Glacier during their lifetime creates various landforms which are as follows:

● Cirque – It is an amphitheatre-shaped basin with precipitations walls, at the heat of glacialvalley. It has three steep sided slope and a flat bottom.

● Tarn – It is a small lake formed near the cirque.

● Arete – It is sharp-edged ridge or rock formed between adjacent cirque.

● Horn – It is mountain ridge formed when the walls of more than two glacial cirque intersect.

● Hanging valley – It is formed when tributary glacier make confluence with main glacierbecause small tributary glaciers are unable to cut deeply as bigger ones.

● U shaped valley – Heavy Glacial mass erodes the base horizontally and vertically and bothproduce U-shaped valley. It has nearby flat bottom.

● Fjord – When a deep glacial trough submerged with sea water, it is known as Fjord. It ismore common in Norway, Greenland and New Zealand.

● Esker – It is a long, shake like or winding ridge of un-assorted depositions of rock, gravel, clayetc. by a stream that ran under or within a glacier.

● Firm or Neve – It is a granular ice formed by recrystallization of snow.

● Kettle – It is a bowl shaped depression formed when a large block of glacial ice breaks awayfrom the main glacier and is buried beneath glacial till it melts.

● Kettle Holes – It is formed when the deposited material in a till plain gets depressed locallyand form a basin.

● Drumlin – It is an inverted boat shaped structure deposited in a till plain of glacier.

● Basal sliding – It is sliding of glacier over the ground on a layer of water.

● Kame – It is a steep sided broken conical mound or ridge or hill or unasserted depositionlooking like hump in a till plane.

● Moraine – Transported material by glacier such as rock fragments, gravel, sand etc. areknown as moraine.

Marine Landforms● A part of the land adjoining or near the sea is called the Sea coast.

● The boundary of a coast, where land meets water is called the Coast line.

● The sea waves deposit sediments of sand and gravel along the shores forming beaches.

● The first longest beach in the world is the Miami Beach in South Florida in U.S.A. The secondlongest beach in the world is the Marina beach in Chennai.

● The sea performs the function of erosion and deposition through sea waves. A wave possesshydraulic action with the help of potential energy as a result of its position above the wavetrough and kinetic energy caused by the motion of the water within the waves.

A number of mechanical and chemical effects produce erosion of rocky shorelines by waves andform following landforms:

● Beaches – A land on shore between the high tide and low tide which composed of sand,clay, fine silt, boulders, Pebbles etc.

● Shingle Beach – When beaches are formed by flat, circular, smooth stones.

● Berrns – It is linear accumulation of shingle beach parallel to the high tide mark.

● Beach cusps – When sand and other large masses like cobbles deposited in the form ofcrescent it is known as cusps.

● Runnels – It is rises and depressions lying parallel to the shoreline.

● Bars – It is the ridges, embankments of sand formed by sedimentation through sea wavesparallel to the shoreline.

● Off shore or longshore bars – It is the bar parallel to the coast but not attached to the land.

● Connecting Bars – It is a bar connecting two islands.

● Tombolo – It is a connecting bar which connects the mainland with an Island.

● Spits – It is sand bars having ends attached to the lands and other projecting to the sea.

● Hook – When spit curved towards the mainland it is known as hook.

● Lagoons – It is formed when the curves or bay are completely enclosed by bars. Forexample, Chilka, Pulikut, Vembanad, Astmudi etc.

● Mudflats – It is the marshy sedimented area characterized by Halophytes Vegetation(Mangroves)

● Cliff – It is the vertical steep precipitous slope above the sea water on a rocky coast.

● Notch – A recess indicating the point of wave attack on the coastline.

● Wave cut platform – A platform at the base and front of a cliff formed when the sea wavesstrike against a cliff and eroded it laterally and retreats.

● Sea Arches – When waves from opposite direction strike a narrow wall of rock differentialerosion of the rock leaves a bridge like structure called sea arches.

● Sea caves – It usually develop from widening and deepening of notches where there areweaknesses in the cliff face.

● Blow holes – Erosive waves may blasts their way vertically through line of weakness in theroofs of cave. They make a peculiar noise, therefore also known as spouting Horns.

● Hanging Valley – When fluvial erosion by streams flowing down the coast is not able to keeppace with the retreat of the cliff, the rivers appear to be hanging over the sea.

Karst Landforms● A karst landforms is a geological feature created on the earth’s surface by drainage of water

into the ground; produced by the dissolution of soluble rocks like limestone, gypsum anddolomite.

Karst landforms, very in size and type and are as follows:

● Sinkholes – It is generally formed in the laterite area by the process of leaching. In itgroundwater dissolve soluble rock creating fracture like structures. Sinkholes pose a threatto developed areas. Some important types of sinkholes are as follows:

o Solution sinkholes – In it little or no sediment is present over limestone; easilydissolved by water.

o Cover subsidence sinkhole – Thick sediments overlay limestones; underlyinglimestone is dissolved sediments dump into the vivid.

o Cover collapse sinkhole – Triggered by heavy rainfall, drought, overloading; causesudden collapse into vivid.

● Karst caves – Rainwater with dissolved carbon dioxide acts like a weak acid that dissolvessoluble rock as it seeps underground. Hollows or cave is created where the water dissolverocks while insoluble rocks stay intact to form the floors and walls of the caves.

● Cenote – When limestone bedrock collapses to form a natural pit that exposes groundwater,known as cenote.

● Fobia – It is a deep natural sinkhole which usually has a shape similar to an inverted funnel.

● Schowle – It includes a variety of karst landforms ranging from irregular labyrinthine hollowsto shallow pits.

● Turlough – It is a disappearing lake found in the limestone areas. For example – In the valleyof River Shannon in Ireland.

● Uvala – It is a combination of many sink holes in a large scattered area.

● Polje – Many yuvala combined to form polje; a large flat plain in karst territory oftenstructurally controlled.

● Karren/Lapiez – These are grooved, fluted features in an open limestone field.

● Cavern – This an underground cave formed by leaching.

● Arch/Natural Bridge – When a part of the cavern collapses the portion which keeps standingforms an arch.

● Blind valley – When streams lose themselves in a polje valley then it’s called blind valley.

● Bourne – Lack of adequate quantity of water reduced erosion leaves them hanging at aheight from the main valley. Thus, also referred as hanging valley. It erodes so much that itgoes very deep.

● Hums – These are curved relict of limestone rocks after erosion.

● Stalactite and stalagmite – These are elongated forms of various minerals deposited fromsolution by slowly dripping water. A stalactite hangs like an icicle from top or sides of thecarven. A stalagmite rising from the floor of the carven.