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Geomorphology at a glance: Major landforms

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Geomorphology, Major landforms, Genetic landform classifications, Volcanic landforms, River Systems and Fluvial Landforms, Aeolian Landforms, Glacial Landforms

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Geomorphology at a glance: Major landforms

  1. 1. 11 Geomorphological process at a glance: major Landforms Prof. P. K. Mani ACSS-751 BCKV, WB, India
  2. 2. Major geological landforms Distribution of the principal folded belts formed since the Precambrian period (after Kummel 1970)
  3. 3. Landforms  Landforms are theLandforms are the individual topographic features exposed on the Earth’s suindividual topographic features exposed on the Earth’s surface.rface.  LandformsLandforms vary in size and shapevary in size and shape and include features such as small creeks or sandand include features such as small creeks or sand dunes, or large features such as the Mississippi River or Blue Ridge Mountains.dunes, or large features such as the Mississippi River or Blue Ridge Mountains.  Landforms develop over a range ofLandforms develop over a range of different time-scalesdifferent time-scales. Some landforms develop. Some landforms develop rather quickly (over a few seconds, minutes, or hours), such as arather quickly (over a few seconds, minutes, or hours), such as a landslidelandslide, while, while others may involve many millions of years to form, such as aothers may involve many millions of years to form, such as a mountain rangemountain range..  Landform development can be relatively simple and involve only a few processes, orLandform development can be relatively simple and involve only a few processes, or very complex and involve a combination of multiple processes and agents.very complex and involve a combination of multiple processes and agents.  Landforms are dynamic features that are continually affected by a variety of earth-Landforms are dynamic features that are continually affected by a variety of earth- surface processes includingsurface processes including weathering, erosion, and deposition.weathering, erosion, and deposition.  Earth scientists who study landforms provide decision makers with information toEarth scientists who study landforms provide decision makers with information to make natural resource, cultural management, and infrastructure decisions, that affectmake natural resource, cultural management, and infrastructure decisions, that affect humans and the environment.humans and the environment. Table Rock Mountain is a metamorphosed igneous intrusion exposed by millions of years of weathering and erosion in South Carolina’s Piedmont Region.
  4. 4. Basic Definitions  TTopography refers to the elevation and relief of the Earth’s surface.refers to the elevation and relief of the Earth’s surface.  Landforms areare the topographic featuresthe topographic features on the Earth’s surface.on the Earth’s surface.  Geomorphology is the study of earth surface processes and landforms.is the study of earth surface processes and landforms. 55 The maps above represent the same area on Earth’s surface and they show three different ways we can view landforms. The image on the far left is a clip from a topographic elevation map, the image in the middle is an infrared aerial photo, and the image on the right is the geologic interpretation of surface sediments and geomorphology. This location is interesting because it contains elements of a natural and human altered physical environment. The lake in the image, (coded blue in the topographic and geology map, and black in the infrared aerial photo) was formed by artificial damming a stream the flows through this landscape.
  5. 5.  TopographyTopography is a term used to describe the Earth’s surface.is a term used to describe the Earth’s surface.  Topography includes a variety of different features, collectively referred to asTopography includes a variety of different features, collectively referred to as landforms.  Topography is measured by the differences inTopography is measured by the differences in elevation across the earth’sacross the earth’s surface. Differences betweensurface. Differences between high and low elevationhigh and low elevation are referred to asare referred to as changes inchanges in relief..  Scientist examine topography using a variety of different sources ranging fromScientist examine topography using a variety of different sources ranging from paper topographic maps to digital elevation models developed using GIS.paper topographic maps to digital elevation models developed using GIS. South Carolina’s elevation relief ranges from 4,590 feet in the Blue Ridge Region to 0 feet along the Coastal Plain. The rivers dissect the topography and drain down-slope from headwaters in the mountainous Blue Ridge and Piedmont, into the alluvial valleys of the Coastal Plain before draining into the Atlantic Ocean. Blue Ridge Piedm ont Coastal Plain Coastal Plain South Carolina: 4 physiographic provinces: Blue Ridge; Piedmont, Sandhills and, Coastal Plain
  6. 6. Constructive and Destructive Processes  Constructive processes build landforms through tectonic and depositional processes.  Tectonic processes include movements at plate boundaries,movements at plate boundaries, earthquakes, orogeny, deformation, and volcanic activity.earthquakes, orogeny, deformation, and volcanic activity.  Deposition is the accumulation or accretion of weathered and erodedis the accumulation or accretion of weathered and eroded materials.materials.  Destructive processes break down landforms through weathering, erosion, and mass wasting.  Weathering is the disintegration of rocks by mechanical, chemical, andis the disintegration of rocks by mechanical, chemical, and biological agents.biological agents.  Erosion is the removal and transportation of weathered material by water,is the removal and transportation of weathered material by water, wind, ice, or gravity.wind, ice, or gravity.  Mass wasting is the rapid down-slope movement of materials by gravity.is the rapid down-slope movement of materials by gravity.  Other Agents and Processes that Affect Landform Development  Climate: temperature, precipitation, water cycle, atmospheric conditionstemperature, precipitation, water cycle, atmospheric conditions  Time: fast and slow rates of change: fast and slow rates of change  People: influences on natural resources and earth surface processes
  7. 7. Constructive Processes  Constructive processes are responsible for physically building or constructing certain landforms. Constructive processes include tectonic and depositional processes and their landforms. Tectonic Landforms are created by massive earth movements due to tectonic and volcanic activity, and include landforms such as: mountains, rift valleys, volcanoes, and intrusive igneous landforms Depositional Landforms are produced from the deposition of weathered and eroded surface materials. Depositional landforms include features such as: beaches, barrier islands, spits, deltas, flood plains, dunes, alluvial fans, and glacial moraines. Floodplain deposits at the confluence of Mississippi and Arkansas Rivers. The Stromboli Volcano erupting off the coast of Sicily in the Mediterranean Sea.
  8. 8. Destructive Processes  Destructive processes create landforms through weathering and erosion of surface materials facilitated by water, wind, ice, and gravity. Mass-wasting events occur in areas where weathering and erosion is accelerated.  Weathering is the disintegration and decomposition of rock at or near the Earth’s surface by mechanical, chemical, or biological weathering processes.  Erosion is the removal and transportation of weathered or unweathered materials by water, wind, ice, and gravity.  Mass-Wasting is a rapid period of weathering and erosion that removes and transports materials very quickly and is often triggered by an environmental stimuli. Mass wasting includes rock falls, landslides, debris and mud flows, slumps, and creep. Landforms formed by destructive processes include river and stream valleys, waterfalls, glacial valleys, karst landscapes, coastal cliffs, and wave- cut scarps.
  9. 9. Reactivated ancient mega-landslide triggered by the March 28, 1999 Garhwal earthquake at Dear in the Alaknanda River Valley. Barnard et al. (2001) dated the ancient landslide to ~8 ka using 10 Be terrestrial cosmogenic nuclides surface exposure dating,
  10. 10. Mohr–Coulomb’s law relates shear strength to cohesion, gravity, and friction. When shear stress (a driving force) exceeds shear strength (a resisting force), then slope failure occurs and the soil moves. In rock, weathering (which may increase cohesion), the presence of joints and bedding planes (which may reduce the angle of friction), pore water (which reduces effective normal stress and increases cohesion), and vegetation (which increases the angle of friction and may increase cohesion) affect shear strength. The Mohr–Coulomb equation defines the shear stress that a body of soil on a slope can withstand before it moves: τs = shear strength of the soil, c = soil cohesion, σ = the normal stress (at right angles to the slope), φ = the angle of internal friction or shearing resistance. The angle φ is not necessarily the slope angle but is the angle of internal friction within the slope mass and represents the angle of contact between the particles making up the soil or unconsolidated mass and the underlying surface. The Mohr–Coulomb equation can be used to define the shear strength of a unit of rock resting on a failure plane and the susceptibility of that material to landsliding, providing the effects of fractures and joints are included. Whenever the stress applied to a soil or rock body is greater than the shear strength, the material will fail and move downslope
  11. 11. Genetic Landform Classification  The genetic landform classification system groups landforms by theThe genetic landform classification system groups landforms by the dominant set of geomorphic processes responsible for their formation.dominant set of geomorphic processes responsible for their formation. This includes the following processes and associated landforms:This includes the following processes and associated landforms:  Tectonic Landforms  Extrusive Igneous Landforms  Intrusive Igneous Landforms  Fluvial Landforms  Karst Landforms  Aeolian Landforms  Coastal Landforms  Ocean Floor Topography  Glacial Landforms  Within each of these genetic classifications, the resulting landforms are a product of either constructive and destructive processes or a combination of both. Landforms are also influenced by other agents orLandforms are also influenced by other agents or processes includingprocesses including time, climate, and human activitytime, climate, and human activity..
  12. 12. Tectonic Landforms  Mountains: Orogenesis and Deformation  Folding  Faulting  Fractures  Domes and Basins  Horst and Graben Rift Valleys  Major Mountain Ranges:  Rocky Mountains  Appalachian Mountains  Himalayan Mountains  Andes Mountains The Valley of Kaveri river near Hogenekal, Dharmapuri dist, TN in the form of gorge
  13. 13. Orogenesis  Orogenesis is the thickening of theOrogenesis is the thickening of the continental crustcontinental crust and theand the building of mountains over millions of years and it translates from Greek as “birth ofover millions of years and it translates from Greek as “birth of mountains”, (mountains”, (orosoros is the Greek word for mountain).is the Greek word for mountain).  Orogeny encompasses all aspects of mountain formation including plate tectonicsOrogeny encompasses all aspects of mountain formation including plate tectonics terrane accretion, regional metamorphism, thrusting, folding, faulting, and igneousterrane accretion, regional metamorphism, thrusting, folding, faulting, and igneous intrusions.intrusions.  Orogenesis is primarily covered in the plate tectonics section of the earth scienceOrogenesis is primarily covered in the plate tectonics section of the earth science education materials, but it is important to review for the landform section becauseeducation materials, but it is important to review for the landform section because it includes deformation processes responsible for mountain building.it includes deformation processes responsible for mountain building. South Carolina’s Blue Ridge Mountains and Inner Piedmont Region were formed by multiple orogenic events when rocks forming South Carolina were uplifted, metamorphosed, folded, faulted, and thrusted. More information on the Blue ridge mountains is included on the section for the Appalachian Mountain Range.
  14. 14. Major Mountain Ranges of the World  Antarctica: Antarctic Peninsula, Transantarctic Mountains  Africa: Atlas, Eastern African Highlands, Ethiopian Highlands  Asian: Himalayas, Taurus, Elburz, Japanese Mountains  Australia: MacDonnell Mountains  Europe: Pyrenees, Alps, Carpathians, Apennines, Urals, Balkan Mountains  North American: Appalachians, Sierra Nevada, Rocky Mountains, Laurentides  South American: Andes, Brazilian Highlands RockyRocky MountainsMountains AndesAndes MountainsMountains AppalachianAppalachian MountainsMountains Himalaya Mountains European AlpsEuropean Alps
  15. 15. Himalaya Mountains  Himalaya orogeny began 45-54 million years ago from the collision between theHimalaya orogeny began 45-54 million years ago from the collision between the India and Eurasian Plates and is still active today.and is still active today.  When two continental plates collide, theWhen two continental plates collide, the Earth’s crust at the plate boundaries is folded, faulted, overthrusted, uplifted forming an extensive continental mountain range.forming an extensive continental mountain range.  Today, the Himalayas separate theToday, the Himalayas separate the Indian sub-continent from thefrom the Tibetan Plateau andand they are recognized as the tallest above sea level mountains on Earth. The Himalayasthey are recognized as the tallest above sea level mountains on Earth. The Himalayas contain 10 of the tallest mountain peaks on Earth >8,000 meters , including Mountcontain 10 of the tallest mountain peaks on Earth >8,000 meters , including Mount Everest with a peak ofEverest with a peak of 8850 meters (29,035 ft). In addition, the Himalayas include(29,035 ft). In addition, the Himalayas include three major individual mountain ranges, thethree major individual mountain ranges, the Karakoram, Hindu Kush, and, and Toba Kakar..  Shallow, intermediate, and deep earthquakes are associated with this zone, predictionare associated with this zone, prediction of several major earthquakes will occur in the region.of several major earthquakes will occur in the region. The name Himalaya is from Sanskirt, and it means “the abode of snow”.Continental – Continental Plate Collision
  16. 16. Intercontinental collision orogen formed where two continental plates collide. An example is the Himalaya.
  17. 17. Volcanic Landforms: Extrusive Igneous 1818 Volcanic Hot-Spots Volcanic Necks Caldera Lava DomesStrato (Composite) Volcanoes Cinder Cones Shield Volcanoes Calderas are bowl-shaped collapse depressions formed by volcanic
  18. 18. Stratovolcano 354 m / 1,161 ft. Indian Ocean Pyroclastic Cone Barren Island, the only historically active volcano along a volcanic arc  connecting Sumatra and Myanmar . The small 3-km-wide island contains a 1.6-km-wide crater partially filled by a cinder cone that has been the source of eruptions since the first was recorded in 1787. Lava flows reached the coast during several recent eruptions. Structure of a Typical strato-volcano
  19. 19. Volcanic landforms B) Chachahén Volcano, Mendoza Province, Argentina, a volcano with strong effect of erosion but no denudation C) Cardiel Lake, Santa Cruz Province, Argentina, a volcanic area under strong effect of denudation, exposing subvolcanic rock body A) Villarrica Volcano, Chile, a volcano without efects of erosion and denudation
  20. 20. Volcanic Landforms: Intrusive Igneous  BatholithsBatholiths  PlutonsPlutons  StocksStocks  MonadnocksMonadnocks  LaccolithsLaccoliths  DikesDikes  SillsSills  VeinsVeins Table Rock in South Carolina is an example of a monadnock landform Half Dome is a granitic igneous intrusion that forms an impressive mountain peak(greater Sierra Nevada Batholith in Yosemite National Park
  21. 21. Enormous granite batholiths often underlie and support the most elevated sections of continental margin orogens, as in the Andes. Intrusions form where molten and mobile igneous rocks cool and solidify without breaching the ground surface to form a volcano. Phacoliths. (a) Occurrence in anticlinal crests and synclinal troughs. (b) Corndon Hill, near Montgomery in Wales, an eroded phacolith
  22. 22. • Subduction of Mediterranean crust under Italy, Greece,Subduction of Mediterranean crust under Italy, Greece, and Turkey continues to cause volcanism and seismicityand Turkey continues to cause volcanism and seismicity • In 1999 an earthquake killed 17,000 people in TurkeyIn 1999 an earthquake killed 17,000 people in Turkey Italy and GreeceItaly and Greece Mount VesuviusMount Vesuvius, Italy, has erupted, Italy, has erupted 80 times since it destroyed Pompeii80 times since it destroyed Pompeii in A.D. 79in A.D. 79 Mount EtnaMount Etna, Sicily, is, Sicily, is Earth’s most active volcanoEarth’s most active volcano
  23. 23. River Systems and Fluvial Landforms  River Systems and Fluvial Landforms  Longitudinal Profile and Watersheds  Lakes and Dams  Mountain Streams  Straight Rivers  Braided Rivers  Meandering Rivers  Anabranching Rivers  Gulleys  River Terraces  River Canyons  Waterfalls  Flood plains  Alluvial Fans Satellite scenes showing braided channel segments of Gandak (left) and Son (right) rivers Arrows show the direction of flow Narmada floodplain inside the high banks of the large flood channel in alluvium. Note mudcracks in the clay. An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Baghmati river system from north Bihar Plains The enormous Brahmaputra- Jamuna River in Asia is a classic example of a braided river.
  24. 24. Entrenched Meanders  Entrenched meanders occur when a river channel cuts down into the flood plain or bedrockEntrenched meanders occur when a river channel cuts down into the flood plain or bedrock and the channel is trapped within a single course and it can not migrate laterally but erodesand the channel is trapped within a single course and it can not migrate laterally but erodes the landscape by down-cutting. This process will often leave behind numerous terraces ofthe landscape by down-cutting. This process will often leave behind numerous terraces of varying width and expose multiple layers of rock.varying width and expose multiple layers of rock.  TheThe Colorado RiverColorado River flowing through theflowing through the Grand Canyon in ArizonaGrand Canyon in Arizona, provides a classic, provides a classic example of entrenched meanders. Down cutting began as the Colorado Plateau wasexample of entrenched meanders. Down cutting began as the Colorado Plateau was uplifted about 5 million years ago and the river responded by eroding into the valley anduplifted about 5 million years ago and the river responded by eroding into the valley and has maintained roughly the same course ever since.has maintained roughly the same course ever since. Below are the entrenched meanders of the Colorado River and to the right is the first geologic interpretation of the numerous geologic units exposed by the down cutting river.
  25. 25. Anabranching  Anabranching river patterns contain multiple channels that weave a mosaic through semi-Anabranching river patterns contain multiple channels that weave a mosaic through semi- permanent alluvial vegetated islands. The islands are often the same height as the floodpermanent alluvial vegetated islands. The islands are often the same height as the flood plain and were likely isolated from the flood plain by meander bend cutoffs, channelplain and were likely isolated from the flood plain by meander bend cutoffs, channel avulsions (abandonment of an entire channel segment), or mid-channel deposition andavulsions (abandonment of an entire channel segment), or mid-channel deposition and subsequent vegetation.subsequent vegetation.  Anabranching rivers often occur in alternating combination with other river forms, such asAnabranching rivers often occur in alternating combination with other river forms, such as meandering, braided, or straight rivers.meandering, braided, or straight rivers.  Anabranching rivers provide added habitat complexity and support rich biodiversity.Anabranching rivers provide added habitat complexity and support rich biodiversity. This section of the Little Pee Dee River in South Carolina represents an anabranching river, most likely formed by channel avulsion (channel abandonment) and reoccupation of both the old and new channel. Upstream and downstream from this segment the river is mainly a single meandering channel with a wide alluvial flood plain and multiple meander bend cutoffs.
  26. 26. An alluvial fan deposited by a hill stream on the way to Amarnath, J & K Natural levee and point bars
  27. 27. 2828 Alluvial fans in a the Indus Valley emerging from in the Nubra Valley The Marble Canyon on the Narmada River downstream of Dhuandhar Falls at Bedhaghat near Jabalpur. The gorge is cut in nearly vertically dipping dolomite rocks
  28. 28. 2929 Rivers are natural streams of water that flow from higher to lower elevations across the land surface. Their continued existence relies upon a supply of water from overland flow, throughflow, interflow, baseflow, and precipitation falling directly into the river. Channelized rivers are streams structurally engineered to control floods, improve drainage, maintain navigation,and so on. In some lowland catchments of Europe, more than 95 per cent of river channels have been altered by channelization. Water flowing in an open channel (open channel flow) is subject to gravitational and frictional forces. Gravity impels the water downslope, while friction from within the water body (viscosity) and between the flowing water and the channel surface resists movement. Viscosity arises through cohesion and collisions between molecules (molecular or dynamic viscosity) and the interchange of water adjacent to zones of flow within eddies (eddy viscosity).
  29. 29. Reynolds number = is a dimensionless number that includes the effects of the flow characteristics, velocity, and depth, and the fluid density and viscosity. mean flow velocity (v), hydraulic radius,(R) kinematic viscosity, υ = /μ ρ molecular viscosity ( ),μ fluid density (ρ) Froude number Re = 500 Laminar Re = 2000,Turbulent V = flow velocity, d = depth of flow √ gd =velocity of the gravity waves F <1 flow, sub critical F = 1 flow, critical F > 1 flow, supercritical /shooting
  30. 30. Flood plains Flood plains are the landform adjacent to theFlood plains are the landform adjacent to the river channel that is influenced by modernriver channel that is influenced by modern river processes. Flood plains areriver processes. Flood plains are constructive, depositional landforms createdconstructive, depositional landforms created by stream flow and sediment deposition.by stream flow and sediment deposition. Flood plain environments are composed of aFlood plain environments are composed of a mosaic of different landform featuresmosaic of different landform features includingincluding cutbankscutbanks,, pointbarspointbars,, naturalnatural leveeslevees,, crevasse channelscrevasse channels andand crevassecrevasse splayssplays,, infilled channelsinfilled channels andand oxbow lakesoxbow lakes,, backswamps, and occasionally, and occasionally yazooyazoo tributariestributaries and other flood plain channels.and other flood plain channels. 3131Copyright ©2008 Google This aerial view of the Mississippi River Valley contains many typical floodplain features. The darker, green areas are floodplain forest and they likely flood the most frequently and thus are not developed with agriculture or housing. The surrounding patchwork represents agricultural fields and other developed lands that are probably at a higher elevation formed by natural or artificial PointbarPointbar CutbankCutbank OxbowOxbow LakesLakes InfilledInfilled ChannelChannel
  31. 31. Meander loop: A single loop of a meandering stream. Cutbank. The bank that experiences erosion. Point bar. The deposits that accumulate opposite the cutbank.
  32. 32. Flood Plains  CutbanksCutbanks form along the outerform along the outer convex margin of meander bendsconvex margin of meander bends. Cutbanks , unlike most. Cutbanks , unlike most floodplain landforms are actuallyfloodplain landforms are actually erosional features formed by the lateral movement of theformed by the lateral movement of the channel across the flood plain. Flood plain sediments are eroded from the cutbank andchannel across the flood plain. Flood plain sediments are eroded from the cutbank and deposited on pointbar surfaces.deposited on pointbar surfaces.  PointbarsPointbars are concave,are concave, depositional landformsdepositional landforms that form opposite of the eroding cutbanks,that form opposite of the eroding cutbanks, and they develop in concert with the laterally migrating river channel.and they develop in concert with the laterally migrating river channel.  Natural leveesNatural levees are depositional landforms formed from the vertical accumulation ofare depositional landforms formed from the vertical accumulation of sediments deposited during flood events. Natural levees form topographically higher surfacessediments deposited during flood events. Natural levees form topographically higher surfaces adjacent to the river channel.adjacent to the river channel.  Crevasse channels and splaysand splays are breaches in the natural levee that result in the fan-are breaches in the natural levee that result in the fan- shaped deposition of flood deposits, beyond or over levee deposits.shaped deposition of flood deposits, beyond or over levee deposits.  Oxbow lakes oror infilled channels form when aform when a meander bend is cut off from the main riverfrom the main river and abandoned in the floodplain.and abandoned in the floodplain.  Backswamps are typically low-lying areas of the floodplain beyond the natural leveeare typically low-lying areas of the floodplain beyond the natural levee deposits. Backswamps contain the finest-textured flood plain deposits and may even developdeposits. Backswamps contain the finest-textured flood plain deposits and may even develop organic-rich soils from the forest litter.organic-rich soils from the forest litter.  Yazoo tributaries are stream networks that enter the floodplain but the natural leveeare stream networks that enter the floodplain but the natural levee prevents the stream from flowing into the river. As a resultprevents the stream from flowing into the river. As a result the yazoo tributary flows parallel to the mainstem river before reaching a breach in the levee or occupying the course of anin the levee or occupying the course of an
  33. 33. GullysGullys  Gullys are formed by hillslope erosion.  Rainwater runoff draining over the surface of a hillslope generates erosive overland flows that remove weathered rocks and soil.  When multiple gullys form they produce a disconnected network of headwater channels that dissect the hillslope and increase soil erosion.  Gullys primarily form on disturbed hillslopes where forest and vegetation have been cleared. The forest was cleared from this hill slope and corn was planted on the bare soil. Following the first few rain events, gullys began to form as a result of soil erosion. The gullys only carry water during rainfall events.
  34. 34. Karst Landforms Caverns Sinkholes Disappearing Streams Springs Towers Karst is a term used to describe landscapes that are formed by chemical weathering process controlled by groundwater activity. Karst landscapes are predominantly composed of limestone rock that contains > 70 percent calcium carbonate. Onondaga Cave in Missouri is a karst landform formed by chemical solution in carbonate limestone rocks. Features within Onondaga Cave include stalagmites, stalactites, dripstones and active flowstone deposits. Missouri known as the “Cave State” Caverns Stalactites are deposits that grow from the ceiling downward and stalagmites are deposits that grow from the ground up (New Mexico)
  35. 35. 3636
  36. 36. Springs  Karst springs are locations whereKarst springs are locations where groundwater emerges from the limestonegroundwater emerges from the limestone and flows across the surfaceand flows across the surface forming a stream or contained pool.forming a stream or contained pool.  The flow of Karst springs is generally dependant on the weather and climate.The flow of Karst springs is generally dependant on the weather and climate. Some are more permanent than others, while others only flow following rainfall orSome are more permanent than others, while others only flow following rainfall or snowmelt events. Springs that are connected to aquifers flow year-round andsnowmelt events. Springs that are connected to aquifers flow year-round and support rich aquatic biodiversity.support rich aquatic biodiversity.  Karst springs generally do not support good water quality, and thus are not safe forKarst springs generally do not support good water quality, and thus are not safe for drinking without filtering the water first; however, the springs often provide fundrinking without filtering the water first; however, the springs often provide fun recreational opportunities and can be a popular place for swimming andrecreational opportunities and can be a popular place for swimming and snorkeling.snorkeling. Karst springs provide cool, clear, water that is inviting for people to swim and snorkelin. Bakreswar spring, WB; and Barton Springs, a karst spring in the Texas Hill Country.
  37. 37. Aeolian Landforms  DunesDunes  Loess FormationsLoess Formations  Carolina BaysCarolina Bays Aeolian landforms are formed by the deposition of wind blown sediments. The sediments are generally sourced from deserts, glacial deposits, rivers or coastal shorelines. Aeolian sediments are often composed of well-rounded, sand-to silt- sized particles, that are weathered by wind abrasion during transport. Sediments are deposited when the velocity of the wind falls and there is not enough energy available to entrain and transport the sediments. uz = wind speed at height z, z = height above the ground, Κ = Kármán constant (≈0.4) z0 = roughness length, u∗ = shear or friction, τ0 = shear force per unit area
  38. 38. 3939 Barchan Dunes Transverse Dunes A Yardang is an elongate ridge or remnant rock feature sculpted by abrasive wind erosion
  39. 39. 4040 Large barchan sand dune at the Shyok-Nubra confluence in Ladakh Etched and grooved limestone formed due to aeolian sand blasting on a hamada surface near Jaisalmer
  40. 40. Loess  Loess deposits are regionally extensive accumulations of windblown silt resulting from thousands of dust storms.  During the dust storms, silt is entrained, transported, and deposited as loess. Loess deposits are generally sourced from either glacial or desert terranes, and silt may be transported for 100's of miles before being deposited.  Loess deposits are generally coarsest and thickest close to their source, and they decrease in thickness and grain size with increasing distance from their source.  Loess is not stratified, meaning it lacks distinctive layers. Instead they are massive accumulations of silt. Loess deposits range from 30 to >100 m thick, and they provide very fertile soils for agriculture and farmland.  The most extensive loess deposit occurs in western and northern China, and it contains sediments that were blown from the deserts of Central Asia. This loess and sandstone contact is from a quarry near Vicksburg, Mississippi where both deposits are being mined. This loess was sourced from glacial till and blown down the Mississippi River Valley. The person in the picture provides a context for the thickness of the loess deposit. LoessLoess SandstoneSandstone
  41. 41. Carolina BaysCarolina Bays  Carolina Bays are oval or elliptical, depressional wetland features enclosed by a low sandy ridge. The depth of Carolina Bays varies depending on their size and land use history,. The depth of Carolina Bays varies depending on their size and land use history, most average about 5-15 feet deep; however, some have been measured with depths greatermost average about 5-15 feet deep; however, some have been measured with depths greater than 30 feet . Sand rims enclosing the Carolina Bays also vary in size, range from 5-15 feet.than 30 feet . Sand rims enclosing the Carolina Bays also vary in size, range from 5-15 feet.  The origin of Carolina Bays: Most Geologists agree that they areThe origin of Carolina Bays: Most Geologists agree that they are eolian landformeolian landforms. Carolinas. Carolina Bays were formedBays were formed 100,000-30,000 years ago100,000-30,000 years ago, during the Quaternary and occur through the, during the Quaternary and occur through the coastal plain of Georgia, South Carolina, North Carolina, Virginia, and Maryland.coastal plain of Georgia, South Carolina, North Carolina, Virginia, and Maryland.  Carolina Bays occur in varying stages of flooding dependant on their land-use history, rainfall,Carolina Bays occur in varying stages of flooding dependant on their land-use history, rainfall, and connection to ground water. Carolina Bays can be dry, temporarily flooded, or support aand connection to ground water. Carolina Bays can be dry, temporarily flooded, or support a permanent lake.permanent lake. Most Carolina Bays have their longest axis oriented from northwest to southeast, although there are a few oriented in other directions. The sand rims are largest along the southeastern edge, but in some cases may be completely lacking. Many Carolina Bays have been drained to support agriculture. Undisturbed Carolina Bays contain unique assemblages of wetland plants and aquatic organisms. This aerial image contains 4 Carolina Bays, three of which support agriculture and one, Woods Bay,. 11 22 33 44 ww.maps.google.com A Carolina Bay extensively drilled in South Carolina revealed that its formation was the result of dissolution of a carbonate coral head and subsequent subsidence of the overlying materials creating the depression in land surface. Within the center of the bay there was no carbonate material detected. Near the rim of the bay, extremely weathered remnants of coral were penetrated and represented the lateral limits of the coral head.
  42. 42. Coastal Landforms  Littoral ZoneLittoral Zone  BeachesBeaches  Barrier IslandsBarrier Islands  Beach RidgesBeach Ridges  SpitsSpits  DeltasDeltas  Coastal CliffsCoastal Cliffs  Marine TerracesMarine Terraces  Wave-Cut ScarpsWave-Cut Scarps Indian coastline Coastal landforms include a diverse array of shoreline and near-shoreline features, as well as some coastal plain landforms far removed from the modern ocean by long term sea-level changes. This section will explore both constructive and destructive landforms formed by current coastal processes, as well as marine related landforms that were formed during periods of higher sea level. The Ganges Delta (Sunderban Delta or the Bengal Delta) Littoral Zone
  43. 43. Coastal and off shore morphology along the Indian subcontinent. GKC= Gulf of kachchh, GKB= Gulf of Khambhat, GM= Gulf of Mannar, PS =Palk Strait. The boundary of Indus and Bengal Fan is approximate. The Bengal fan, with an area of ~ 3 million km2 is the largest deep sea fan in the world. The area of Indus Fan is ~ 1.1 m Km2 .
  44. 44. The zone in the ocean that experiences the effects of the tides. It is the region of the sea between high and low tides. t is sometimes called the intertidal zone. The LITTORAL zone
  45. 45. This wave-cut scarp and platform near Brigden, South Wales was formed by the erosive action of the sea’s waves. Sea arches form by erosive wave refraction on opposite sides of a headland Sea cliffs are erosional landforms formed by the undercutting action of the sea against the coastline San Mateo County, California Wave-cut platform in khondalites 10 km southwest of harbor channel in Visakhapatnam on the east coast
  46. 46. Glacial Landforms  Ice sheets and Alpine Glaciers  Ice Field and Ice Caps  Piedmont Glacier  Tidal Glaciers and Icebergs  Glacial U-shaped Valleys  Fjords  Hanging Valleys  Cirques and Cirque Glaciers  Arêtes, Horns, Cols  Lateral and Medial Moraines  End and Terminal Moraines  Paternoster Lakes  Kettles  Erratics  Drumlins  Outwash Plain Glaciers are large masses of moving ice. Because glaciers are “frozen” they are part of the Earth’s cryosphere, which accounts for 77 percent of all Earth’s freshwater. Glaciers are very sensitive to the slightest temperature changes. Over Earth’s geologic history the spatial extent and size of glaciers has expanded and shrunk numerous times. As a result, glacial landforms can be found in locations that currently have no active glaciers or glaciation processes. Presently, glacial landforms occur in two distinct geographic regions, high latitude polar environments and high altitude mountain environments. In this section we will explore glacial landforms from their present context and from a historic look into the past. Alpine Valley Glacier in Alaska. ρi = ice density, h = ice thickness, β = ice-surface slope. Hydrostatic pressure depends on the weight of the overlying ice and is spread equally in all directions. Shear stress depends upon the weight of the ice and the slope of the ice surface GLACIER FLOW shear stress, τ0
  47. 47. 4848 Glaciers flow because ice deforms as a result of basal shear stress. Driving and resisting stresses operating on a block of ice on an inclined slope. Glacier flow Glacier flow is a combination of the deformation of the ice and the bed, and sliding of ice over its bed. Glacier velocity therefore equals deformation plus basal sliding. Glacier Deformation Glaciers flow because permanent deformation occurs as a result of strain in response to stress. Strain may include deformation of the ice or the sediments at the ice-bed interface, or sliding at the ice-bed interface. Resistance to strain depends on ice temperature, crystal structure, bed roughness, debris content, water pressure and other factors. Glen’s power flow law gives the shear strain and applied stress in ice: ε is the strain rate, A and n are constants, and τ is the basal shear stress. The constant n = 3
  48. 48. 4949Pindari Glaciers We have many glaciers in our country moving down the slopes and valleys in Himalayas. Higher reaches of Uttaranchal, H. P. and J & K, are places to see some of them. River Bhagirathi is basically fed by melt waters from under the snout (Gaumukh) of the Gangotri Glacier. In fact, Alkapuri glacier feeds waters to Alakananda river. Some glacial erosional and depositional forms ( Spencer, 1962) Siachen Glacier Karakoram range in the Himalaya
  49. 49. Major Landforms of India 1.Mountains – The Himalayan mountain range is a major landform in India. It borders on the Northern part of India Mount Everest is located in the Himalyan range. The Aravalli range – This is situated in the western part of India and runs about 800 km from the northeast to the south west, traversing Rajasthan. 2. Volcanoes – These are found in the Andaman Islands such as Barren Islands, Baratang, Narcondam and Deccan Traps. The volcanoes are dormant and active. 3. Glaciers – These are found in Jammu and Kashmir, Himachal Pradesh, Uttarkhand and Sikkim. The Siachen glacier happens to be the largest glacier outside of the polar region. It is the largest in the Himalayas - Karakoram. It is in Jammu and Kashmir. 4. Valleys – The Damodar Valley in Jharkahand and West Bengal. The Araku valley in Vishakapatnam in Andhra Pradesh The Kashmir valley is very beautiful.
  50. 50. 5. Deserts – The Thar Desert is the Great Indian Desert and lies in Rajasthan. 6. Islands – The Andaman Islands are very famous. They are in the Bay of Bengal. The Nicobar islands are in the eastern Indian Ocean. 7. Waterfalls – Famous water falls are Chitrakot which is 100 ft, Chattisgarh. •Then you have the Kuntala Falls in Andhra Pradesh. •The Dudhsagar Falls is 1,017 feet. Situated in Goa. •The Jog Falls in Karnatka 8. Beaches – Goa, one comes across several beaches. Here, the Arambol beach is famous as well as the Anjuna Beach and many more, •The Vizag beach is famous in Andhra Pradesh. • In Madras, the Marina beach and the Adyar beach are very popular 9. Plains – the Indo-Gangetic plain is very famous. It is extremely fertile and is in the northern part of India. The Eastern coastal and Western coastal are other regions which are part of the plains in India
  51. 51. India's geological features can be divided based on their formation in different periods of the Geological Time Scale. Accordingly, India's geographical land can be classified into Deccan Trap, Gondwana ,  Vindhyan, and into those that originated in Pleistocene, Tertiary, and Pre-Cambrian Period The Deccan Trap covers almost all of Maharashtra, a part of Gujarat, Karnataka, MP and AP marginally. Geologists believe that the Deccan Trap was formed as result of sub-aerial volcanic activity associated with continental divergence in this part of the earth during the Mesozoic era. The rocks found in this region are generally of igneous type. 
  52. 52. The Gondwana and Vindhyan include within its fold parts of Madhya Pradesh, Chhattisgarh, Orissa, Andhra Pradesh, Maharashtra, Jammu and Kashmir, Punjab, Himachal Pradesh, Rajasthan and Uttaranchal The Gondwana Supergroup forms a unique sequence of fluviatile rocks deposited in Permo-Carboniferous & Mesozoic times. Damodar and Sone river valley and Rajmahal hills in the eastern India are repositories of the Gondwana rocks.  The vast plateau mountains to the north of Narmada River in Madhya Pradesh and the adjoining areas of Malwa Plateau and Gangetic Plains form the Vindhyan cover. Here, the Deccan Trap and the alluvium conceal the rocks. The lower Vindhyans (Semri Group) are dominantly limestones, whereas the upper parts of the succession are mostly sandstones Formations, which are of recent or Pleistocene origin, are found over relatively large area of India. Parts of the geographical area of the states of Uttar Pradesh, Rajasthan, Punjab, Gujarat, Madhya Pradesh, Tamil Nadu, Andhra Pradesh, Orissa, Kerala, Karnataka, Maharashtra, Assam, Bihar and Haryana come under this geological category

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