Lithosphere and geomorphologyLithosphere and geomorphology

LithosphereLithosphere

• The Earth consist of the The Earth consist of the crust, the mantle and the crust, the mantle and the core. core. LithosphereLithosphere is is created by the Earth’s created by the Earth’s crust and solid mantle. It crust and solid mantle. It lies upon the plastic lies upon the plastic mantle rock - mantle rock - astenosphereastenosphere. . Lithosphere is studied by Lithosphere is studied by geologygeology. It is the science . It is the science which study the origin, which study the origin, structure, composition and structure, composition and history of the Earth.history of the Earth.

Lithosphere-crust:Lithosphere-crust:

• The crustThe crust is the outer layer is the outer layer which is thin and rigid. It floats which is thin and rigid. It floats on the semi-molten rock on the semi-molten rock mantle. It can be divided into mantle. It can be divided into two main types continental two main types continental crust and oceanic crust. crust and oceanic crust.

• Continental crust (150 – Continental crust (150 – 250 km thick)250 km thick) – granitic crust – granitic crust because it consist of SiAl(silica because it consist of SiAl(silica & aluminum)-, covers the land & aluminum)-, covers the land surface, the base of land surface, the base of land mass, it is thicker and lighter mass, it is thicker and lighter than oceanic crustthan oceanic crust

• Oceanic crust – Oceanic crust – basaltic crust basaltic crust because it consist of SiMg because it consist of SiMg (silica & magnesium), granitic (silica & magnesium), granitic layer missing cover the floor of layer missing cover the floor of world’s oceanworld’s ocean

• In the core of the Earth is radioactive decay In the core of the Earth is radioactive decay from which the convection currents escape from which the convection currents escape towards the surface. They tear the crust towards the surface. They tear the crust apart and dividing it into huge fragments – apart and dividing it into huge fragments – tectonic plates (crustal plates) – tectonic plates (crustal plates) – moving away from each other(divergence) moving away from each other(divergence) or being pushed together (convergence).or being pushed together (convergence).

• Crustal plates are pushed across the Earth’s Crustal plates are pushed across the Earth’s surface at 50mm/y.surface at 50mm/y.

• Continental drift – process- continents Continental drift – process- continents constantly changed position and size.constantly changed position and size.

• Major tectonic plate: Eurasian, North Major tectonic plate: Eurasian, North American, South American, African, Pacific, American, South American, African, Pacific, Nazca, IndoAustalian, Antarctic, PhillipineNazca, IndoAustalian, Antarctic, Phillipine

Map of tectonic plateMap of tectonic plate

• Crustal plates can converge, diverge or collide.We know 3 main Crustal plates can converge, diverge or collide.We know 3 main types of plate boundaries according to the direction and types of plate boundaries according to the direction and movement of the plates.movement of the plates.

• Diverging(constructive) –Diverging(constructive) – forced apart and new crust is forced apart and new crust is created between (e.g. under the ocean – magma reaching the created between (e.g. under the ocean – magma reaching the sea floor producing new oceanic crust) - Mid Atlantic Ridge sea floor producing new oceanic crust) - Mid Atlantic Ridge (Europe is moving away from North America)(Europe is moving away from North America)

• Converging( destructive)Converging( destructive) – one plate collides with another, – one plate collides with another, slides under the other (e.g. heavier oceanic plate slides below slides under the other (e.g. heavier oceanic plate slides below the lighter continental plate- subduction zone ) – Nazca plate the lighter continental plate- subduction zone ) – Nazca plate sinks under the South America plate sinks under the South America plate

• SlippingSlipping – 2 plates move horizontally ”slip” past one other – The – 2 plates move horizontally ”slip” past one other – The Indian plate collide with the Eurasian plate to form the Indian plate collide with the Eurasian plate to form the HimalayasHimalayas

• Plate boundariesPlate boundaries Rift valleys – East African Rift ValleyRift valleys – East African Rift Valley Mid- oceanic ridges – Mid-Atlantic ridgeMid- oceanic ridges – Mid-Atlantic ridge Fold mountains – HimalayasFold mountains – Himalayas Horizontal faults – San Andreas in USAHorizontal faults – San Andreas in USA

Tectonic plateTectonic plate

Diverging, converging and slipping boundariesDiverging, converging and slipping boundaries

East African Rift Valley and Mid-Atlantic RidgeEast African Rift Valley and Mid-Atlantic Ridge

Himalayas and San Andreas in USAHimalayas and San Andreas in USA

• Region where the Earth’ lithosphere forms, are typical for Region where the Earth’ lithosphere forms, are typical for huge seismic and volcanic activityhuge seismic and volcanic activity, , tectonic tectonic movementsmovements and and endogenic processesendogenic processes which take place which take place within the Earth.within the Earth.

• Tectonic movementsTectonic movements- mechanical movements of the - mechanical movements of the crust caused by pressure, tension of gravitation, e.g. crust caused by pressure, tension of gravitation, e.g. mountain foldingmountain folding

Tectonic forces (movements) create many crustal failures: Tectonic forces (movements) create many crustal failures: faults and foldsfaults and folds

• faulting faulting usually occurs during an earthquake usually occurs during an earthquake

• FaultFault - fracture in a rock which involves a movement along one side or - fracture in a rock which involves a movement along one side or both sides.both sides.

• ShiftShift - total movement - total movement

• ThrowThrow - vertical displacements- vertical displacements

• HeaveHeave - horizontal displacements- horizontal displacements

• Normal faultNormal fault - result of a - result of a tension, strata are pulled tension, strata are pulled apart, one side of it is apart, one side of it is thrown down - increase of thrown down - increase of land area (divergence)land area (divergence)

• Reverse (thrust) faultReverse (thrust) fault - result of a - result of a compression, one side compression, one side of the fault plain is of the fault plain is thrust over the other thrust over the other (convergence) - (convergence) - overlapping of the overlapping of the strata and the surface strata and the surface area is decreased, e.g. area is decreased, e.g. steep slopes are formed steep slopes are formed of more resistant rocks, of more resistant rocks, gentle slopes are found gentle slopes are found on softer rocks that are on softer rocks that are thrown down (by thrown down (by erosion)erosion)

• Wrench (tear) faultWrench (tear) fault - - movement is horizontal but movement is horizontal but the fracture is vertical, the fracture is vertical, nearby plate boundaries nearby plate boundaries (product of an earthquake)(product of an earthquake)

Landforms produced by faults:Landforms produced by faults:

• HorstHorst = upland area bounded by low = upland area bounded by low ground either side (fault scarps) ground either side (fault scarps) a) uplift of a blocka) uplift of a blockb) depression of surrounding landb) depression of surrounding lande.g.: e.g.: Harz Mts., Black ForestHarz Mts., Black ForestExtensive horst produce plateau areas Extensive horst produce plateau areas (block mountains). Further Earth (block mountains). Further Earth movements tilt the blocks = movements tilt the blocks = tilted tilted blocks blocks = they are divided by faults into = they are divided by faults into subsided (wide deep basins) and subsided (wide deep basins) and elevated sections (mountains).elevated sections (mountains).

• Rift valley (graben)Rift valley (graben) = reverse of a = reverse of a horst, it´s formed by tension, horst, it´s formed by tension, compression or parallel faults and compression or parallel faults and accompanied by horsts on either side, accompanied by horsts on either side, also can be formed nearby plate also can be formed nearby plate boundaries where the plates are boundaries where the plates are pulling apart (e.g. East African Rift pulling apart (e.g. East African Rift Valley).Valley).

• folding folding occurs when layers of rock areoccurs when layers of rock are distorted but not distorted but not fracturedfractured

• FoldFold - distorted layers of rock - distorted layers of rock

• Simple foldSimple fold - anticline + syncline - anticline + syncline

• Recumbent fold Recumbent fold - crumpled several times- crumpled several times

• Asymmetric foldAsymmetric fold

• Over foldOver fold

Earthquakes – seismic activityEarthquakes – seismic activity

• - tremors or ground movements caused by shock waves => - tremors or ground movements caused by shock waves => occur normally at plate boundaries. Plate movement causes occur normally at plate boundaries. Plate movement causes stress to build up within the crustal rocks until the rocks break stress to build up within the crustal rocks until the rocks break along the line of a fault or cracks in the Earth´s crust.along the line of a fault or cracks in the Earth´s crust.

• Actual movement = few cms but the sudden release of seismic Actual movement = few cms but the sudden release of seismic (earthquake) energy can be enormous(earthquake) energy can be enormous

• focusfocus - the point at which the rocks break within the crust. This - the point at which the rocks break within the crust. This may be some distance below the surface and the seismic may be some distance below the surface and the seismic energy emitted from the focus travels in all directions as energy emitted from the focus travels in all directions as seismic waves.seismic waves.

• epicentreepicentre.- the point on the Earth´s surface above the focus .- the point on the Earth´s surface above the focus

• More powerful earthquake is when:More powerful earthquake is when:· stress was built up for a long time· stress was built up for a long time· focus is near the surface· focus is near the surface

• Each year - thousands of earthquakes => few are centred Each year - thousands of earthquakes => few are centred near populated areas and strong enough to cause loss of lives near populated areas and strong enough to cause loss of lives - - primary effectsprimary effects (from the violent shaking of the ground (from the violent shaking of the ground during an earthquake), e.g.during an earthquake), e.g.· buildings may collapse killing people inside them,· buildings may collapse killing people inside them,

· shattered window glass may shower on to the streets below· shattered window glass may shower on to the streets below· huge cracks may open in the ground· huge cracks may open in the ground· roads may be damaged· roads may be damaged· water pipes and (electricity) mains may be cut off· water pipes and (electricity) mains may be cut off

• Primary effects can generate Primary effects can generate secondary effectssecondary effects, e.g., e.g.· deaths because of food and water shortage· deaths because of food and water shortage· fires _ gas or oil leaking from fractured pipes· fires _ gas or oil leaking from fractured pipes· diseases _ lack of medical care and clean drinking water· diseases _ lack of medical care and clean drinking water· tsunamis _ huge waves caused when earthquake occurs · tsunamis _ huge waves caused when earthquake occurs under the sea (1000 kph in open water, 65kph close to land + under the sea (1000 kph in open water, 65kph close to land + 15 m high). Created by displacing of the seabed (seafloor) => 15 m high). Created by displacing of the seabed (seafloor) => great damages to coastal areas.great damages to coastal areas.

• Geomorphological effects = land movements, tsunami, Geomorphological effects = land movements, tsunami, landslides, avalanches.landslides, avalanches.

Volcanoes – volcanic activityVolcanoes – volcanic activity

• Geothermal heatGeothermal heat is released from the Earth´s core at the surface mainly through is released from the Earth´s core at the surface mainly through volcanoes.volcanoes.

• Magma pours onto the surface as lava – Magma pours onto the surface as lava – acid & basicacid & basic..

• Acid lava volcanoAcid lava volcano - mainly steep-sided, common along destructive plate - mainly steep-sided, common along destructive plate boundaries, Magma - melting of basaltic oceanic crust and marine sediments, (e.g. boundaries, Magma - melting of basaltic oceanic crust and marine sediments, (e.g. volcanoes of Phillipines)volcanoes of Phillipines)

• Basic lava volcanoBasic lava volcano - common along constructive - common along constructive plate boundaries, magma - basalt plate boundaries, magma - basalt arising directly from the mantle, e.g. Mauna Loa in Hawaiiarising directly from the mantle, e.g. Mauna Loa in Hawaii

• Geothermal activityGeothermal activityAreas with geothermal activity = crust is thin and magma is present at quite shallow Areas with geothermal activity = crust is thin and magma is present at quite shallow depth-depth-magma heats rocks above it (350°C at a depth of less than 5 km). Percolating magma heats rocks above it (350°C at a depth of less than 5 km). Percolating groundwater is heated and then driven upwards by convection through cracks in the groundwater is heated and then driven upwards by convection through cracks in the crust. Superheated watercrust. Superheated waterbegins to boil closer to the surface and then is emitted onto the surface -begins to boil closer to the surface and then is emitted onto the surface -· fumerole (superheated water turned to steam because of the sudden drop in · fumerole (superheated water turned to steam because of the sudden drop in pressure)pressure)· mudpool (bubbling pool of mud – liquefied soil where steam condenses near · mudpool (bubbling pool of mud – liquefied soil where steam condenses near surface)surface)· hot spring (superheated water + cold groundwater = hot spring at the surface)· hot spring (superheated water + cold groundwater = hot spring at the surface)· geyser (regular eruption of hot water and steam, e.g. geysers in New Zealand)· geyser (regular eruption of hot water and steam, e.g. geysers in New Zealand)

Endogenic processesEndogenic processes• processes within the Earthprocesses within the Earth

• PlatformsPlatforms - shields and tables - basic building elements of all the continents - The older the platform, - shields and tables - basic building elements of all the continents - The older the platform,• the smaller the relief!the smaller the relief!

• Mobile orogenic zonesMobile orogenic zones- fold (range) mountains from Paleozoic, Mesozoic and Tertiary ages- fold (range) mountains from Paleozoic, Mesozoic and Tertiary ages

• Land massLand massShieldsShields - cores of the land mass, e.g. old Scandinavian, Canadian, African, Australian shield created - cores of the land mass, e.g. old Scandinavian, Canadian, African, Australian shield created by old igneous (granite) and metamorphic (marble) rocksby old igneous (granite) and metamorphic (marble) rocks

Tables -Tables - parts of platforms where older fold parentn rock was covered by younger (sedimentary) parts of platforms where older fold parentn rock was covered by younger (sedimentary) rocks - plainsrocks - plains (East-European)(East-European)

Orogenic zonesOrogenic zones = determined by faults, originated in platform rims or in between them -mountain = determined by faults, originated in platform rims or in between them -mountain folding activityfolding activity

• OceanOcean

Oceanic floorOceanic floor - continental shelf, continental slope, abyssal plain, seamounts, mid-oceanic - continental shelf, continental slope, abyssal plain, seamounts, mid-oceanic ridges,volcanic islands and trenchesridges,volcanic islands and trenches

Oceanic platformsOceanic platforms – the biggest part of ocean’s floor, they are called basins, e.g. Brazil, Argentine – – the biggest part of ocean’s floor, they are called basins, e.g. Brazil, Argentine – south-west part of Atlantic oceansouth-west part of Atlantic ocean

Oceanic mobile zonesOceanic mobile zones - midoceanic ridges, long and narrow mountain ranges, somewhere occurring - midoceanic ridges, long and narrow mountain ranges, somewhere occurring above the sea level as islands (Pacific Ocean), their length is about 45 000 km e.g. Mid-Atlantic Ridgeabove the sea level as islands (Pacific Ocean), their length is about 45 000 km e.g. Mid-Atlantic Ridge

RocksRocks• In the upper part of lithosphere we can find all the chemical elements. There are In the upper part of lithosphere we can find all the chemical elements. There are

mostly silicate minerals which are combination of oxide, silicon and some other mostly silicate minerals which are combination of oxide, silicon and some other metals – micametals – mica

• rocksrocks - composition of minerals or organic remains - composition of minerals or organic remains igneous rocksigneous rocks sedimentary rockssedimentary rocks metamorphic rocksmetamorphic rocks

• Metamorphic rocksMetamorphic rocks - is formed by pressure and extreme heat applied to existing - is formed by pressure and extreme heat applied to existing rocks within the earth’s crust causing them to change their mineral structure and rocks within the earth’s crust causing them to change their mineral structure and texture. E.g marble, gneisstexture. E.g marble, gneiss

Igneous rockIgneous rock-created by crystallization of -created by crystallization of silicate minerals, water and various gases silicate minerals, water and various gases consist of magma or lava. consist of magma or lava. According to the presence of SiO2, rocks are According to the presence of SiO2, rocks are divided into:divided into:

- acid, e.g. granite, - acid, e.g. granite, - neutral, e.g. andesite, - neutral, e.g. andesite, - basic, e.g. basalt, - basic, e.g. basalt,

Sedimentary rocksSedimentary rocks -is formed by deposition of -is formed by deposition of rock particles that have been eroded. rock particles that have been eroded. Mechanical and chemical disruption of rocks is Mechanical and chemical disruption of rocks is called called weatheringweathering..

- Mechanical weathering- Mechanical weathering = = disintegration of rocks by the influence of disintegration of rocks by the influence of different temperatures, frost or organism´s different temperatures, frost or organism´s activity.activity.

- Chemical weathering- Chemical weathering = rocks are = rocks are decomposited by air and water (by chemical decomposited by air and water (by chemical processes) and changed into rocks of different processes) and changed into rocks of different nature compared to the previous ones. e.g nature compared to the previous ones. e.g sandstone, limestone, dolomitesandstone, limestone, dolomite

Metamorphic rocksMetamorphic rocks - is formed by pressure and extreme heat applied to - is formed by pressure and extreme heat applied to existing rocks within the earth’s crust causing them to change their mineral existing rocks within the earth’s crust causing them to change their mineral structure and texture. E.g marble, gneissstructure and texture. E.g marble, gneiss

GeomorphologyGeomorphology• - is science about the Earth’s relief. It studies the formation, evolution and character of relief - is science about the Earth’s relief. It studies the formation, evolution and character of relief

and its forms. and its forms.

• -it is a landmark between solid lithosphere + pedosphere and liquid hydrosphere + gaseous -it is a landmark between solid lithosphere + pedosphere and liquid hydrosphere + gaseous atmosphereatmosphere

• Relief (Georelief)Relief (Georelief) - complex of shapes of the Earth’s surface, it is created by - complex of shapes of the Earth’s surface, it is created by geomorphological processes – many forms of georelief e.g. slopes, valley, mountains, basins, geomorphological processes – many forms of georelief e.g. slopes, valley, mountains, basins, lowlands, plateaux, plains, etc. Relief also influences other parts of the Earth e.g. flora, lowlands, plateaux, plains, etc. Relief also influences other parts of the Earth e.g. flora, fauna, climate, construction of buildings, agriculture, etcfauna, climate, construction of buildings, agriculture, etcMany forms of it can be a disaster for people.e.g. landslides, avalanches, earthquakes, Many forms of it can be a disaster for people.e.g. landslides, avalanches, earthquakes, volcanoes, soil erosion, etc.volcanoes, soil erosion, etc.

• The most basic feature of the relief is – The most basic feature of the relief is – altitude.altitude. Also there are many others: Also there are many others: descend (slope) linedescend (slope) line – a line perpendicular to countours (contour lines) – a line perpendicular to countours (contour lines) aspectaspect – orientation to points of the compass (cardinal points) e.g. southern aspect receives – orientation to points of the compass (cardinal points) e.g. southern aspect receives more insolationmore insolation crest linecrest line – line joining places of a crest, places of the highest altitude upon a crest – line joining places of a crest, places of the highest altitude upon a crest valley linevalley line – line joining places of a valley, places of the lowest altitude within a valley – line joining places of a valley, places of the lowest altitude within a valley

• Vertical segmentation of reliefVertical segmentation of relief - vertical difference (meters) between the highest and the - vertical difference (meters) between the highest and the smallest point of certain area.smallest point of certain area.

• Horizontal segmentation of reliefHorizontal segmentation of relief - the number of valley lines - the number of valley lines

• Hierarchy of relief formsHierarchy of relief formsSmaller areas are parts of larger ones - riverbed - flat - valley - mountain range – continentSmaller areas are parts of larger ones - riverbed - flat - valley - mountain range – continent

WeatheringWeathering • - decomposition and disintegration of rocks in situ (in the same place)- decomposition and disintegration of rocks in situ (in the same place)• - breaking down of rock into smaller components at or near the Earth´s surface- breaking down of rock into smaller components at or near the Earth´s surface

• 3 types of weathering:3 types of weathering:– – Mechanical (physical) weatheringMechanical (physical) weathering– – Chemical weatheringChemical weathering– – Biological weatheringBiological weathering

• Chemical weatheringChemical weathering = = decomposition of a rock, rocks are broken down by chemical decomposition of a rock, rocks are broken down by chemical reactions e.g. kaolinitereactions e.g. kaoliniteCarbonationCarbonation::Rainwater absorbs carbon dioxide (CO2) as it falls through the air and soaks Rainwater absorbs carbon dioxide (CO2) as it falls through the air and soaks through the soil. This makes is acidic. It will attack rocks composed of calcium carbonate through the soil. This makes is acidic. It will attack rocks composed of calcium carbonate (CaCO3) e.g limestone(CaCO3) e.g limestoneOxidationOxidation:: Metals and metallic minerals (Fe) in rocks combine with oxygen (O2) from the air Metals and metallic minerals (Fe) in rocks combine with oxygen (O2) from the air to form another substanceto form another substance.. Rocks which contained of iron are especially weathered by this Rocks which contained of iron are especially weathered by this process.process.HydrolysisHydrolysis:: Some rock minerals combine with rainwater and break down into other chemical Some rock minerals combine with rainwater and break down into other chemical forms. This process of hydrolysis is important in producing sand and clay when water (H2O) forms. This process of hydrolysis is important in producing sand and clay when water (H2O) combines granite. combines granite.

• Mechanical (physical) weatheringMechanical (physical) weathering - disintegration of a rock, rocks break up due to stress - disintegration of a rock, rocks break up due to stress e.g. screee.g. scree Freeze-thawFreeze-thaw (ice crystal growth or frost shattering) – water expands by 1/10 when it (ice crystal growth or frost shattering) – water expands by 1/10 when it freezes (below 0°C) – ice crystals in a rock grow and then a rock is splitted as a result of the freezes (below 0°C) – ice crystals in a rock grow and then a rock is splitted as a result of the pressurepressure

• Biological weathering (biotic forces)Biological weathering (biotic forces) - mechanical + chemical weathering e.g plants´ - mechanical + chemical weathering e.g plants´ roots, animals, etc.roots, animals, etc.

Slope processesSlope processes

• SlopeSlope - any part of the solid land surface. - any part of the solid land surface.

• Slope Slope - an inclined surface or hillslope- an inclined surface or hillslope• - an angle of inclination or slope angle- an angle of inclination or slope angle

• Surfaces can be:Surfaces can be:sub-aerial sub-aerial (exposed)(exposed)ssub-marine ub-marine (underwater)(underwater)aggradational aggradational (depositional)(depositional)degradational degradational (erosional)(erosional)transportational transportational or any mixture of these.or any mixture of these.

• Geography (geomorphology)Geography (geomorphology) studies the hillslope = area between the watershed and studies the hillslope = area between the watershed and the basethe base

• Slope formSlope form = the shape of the slope in cross-section = the shape of the slope in cross-section

• Slope processesSlope processes = activities acting on the slopes = activities acting on the slopes

• Slope evolutionSlope evolution = development of slopes with time = development of slopes with time

• Endogenic processesEndogenic processes occur within the Earth (tectonic forces) occur within the Earth (tectonic forces)

• Exogenic processesExogenic processes operate at/near the Earth´s surface operate at/near the Earth´s surface (weathering/erosion, mass movements) large-scale movement of (weathering/erosion, mass movements) large-scale movement of the Earth’s surface without a moving agent(river, glacier) e.g. the Earth’s surface without a moving agent(river, glacier) e.g. rockfall, landslide, mudflow, avalancherockfall, landslide, mudflow, avalanche

• The simplest model of slope form:The simplest model of slope form:waning slope (concave)waning slope (concave)scree slopescree slopecliffcliffwaxing slope (convex)waxing slope (convex)

• Slopes - an open system - „active“ processes that shape „passive“ Slopes - an open system - „active“ processes that shape „passive“ materials:materials:

• Inputs:Inputs:energy (insolation)energy (insolation) mass (water and sediment)mass (water and sediment)

• Outputs:Outputs:energy (re-radiated heat)energy (re-radiated heat)mass (water regolith)mass (water regolith)

Mass movementsMass movements

• - large-scale movement of the Earth’s surface without a moving - large-scale movement of the Earth’s surface without a moving agent(river, glacier, ocean wave), type of exogenic processesagent(river, glacier, ocean wave), type of exogenic processes

• Mass movement:Mass movement:very slowvery slow – soil creep – soil creepfastfast – avalanche – avalanchedrydry – rock fall – rock fallfluid (wet)fluid (wet) – mud flow – mud flow

• Mass movement on the slope is determined by:Mass movement on the slope is determined by:1. gravity1. gravity- it can move the material down slope - slide component- it can move the material down slope - slide component- it holds the particle to the slope - stick component- it holds the particle to the slope - stick component2. slope angle2. slope angle – the downslope movement is proportional to the – the downslope movement is proportional to the weight of the particle and to the slope angleweight of the particle and to the slope angle3. pore pressure3. pore pressure – water fills the spaces between the particles, – water fills the spaces between the particles, lubricates them and pushes them apart under pressure, very lubricates them and pushes them apart under pressure, very important in movement of wet material on low-angle slopesimportant in movement of wet material on low-angle slopes

Types of mass movementTypes of mass movement

• Surface wash – Surface wash – takes place when soil’s infiltration capacity has been exceeded,in particular when the ground is frozen takes place when soil’s infiltration capacity has been exceeded,in particular when the ground is frozen or heavily saturated, on the other hand, it might take place also in semi-arid and arid regions where particles’ size or heavily saturated, on the other hand, it might take place also in semi-arid and arid regions where particles’ size prevent percolationprevent percolation

• SheetwashSheetwash – unchannelled flow of water over a soil surface, is capable of transporting material dislodged by – unchannelled flow of water over a soil surface, is capable of transporting material dislodged by rainsplacsh. On most slopes it breaks into areas of high velocity and areas of lower velocity.rainsplacsh. On most slopes it breaks into areas of high velocity and areas of lower velocity.

• ThroughflowThroughflow – takes place when water moves down through the soil. It is chennelled into natural pipes in the soil, it – takes place when water moves down through the soil. It is chennelled into natural pipes in the soil, it gives the sufficient energy to transport material of considerable volume.gives the sufficient energy to transport material of considerable volume.

• Heave/creepHeave/creep – small – scale movement occurring mostly in winter. – small – scale movement occurring mostly in winter.

• Talus creepTalus creep – slow movement of fragments on a scree slope – slow movement of fragments on a scree slope

• Rainsplash erosionRainsplash erosion – erosive effect of raindrops on hillslope – erosive effect of raindrops on hillslope

• Falls Falls - on steep slopes (>70°) weathered rocks are detached and fall due to gravity - on steep slopes (>70°) weathered rocks are detached and fall due to gravity -short fall - produces a straight scree-short fall - produces a straight scree-long fall - -long fall - produces a concave screeproduces a concave scree

• SlidesSlides - when the whole mass of material moves along a slip plane - when the whole mass of material moves along a slip plane - - rocksliderockslide – – schist, micaschist, mica- - landslidelandslidea) downslope force > the resistance (friction and cohesion)a) downslope force > the resistance (friction and cohesion)b) material moves downslope after a shear failureb) material moves downslope after a shear failure

• SlumpsSlumps - rotational slides on softer rocks (claystone) along a curved plane. - rotational slides on softer rocks (claystone) along a curved plane.

• Flows Flows - continuous, fluent movements of fine, deeply weathered clay, saturated with water=> highly fluid, no cohesion- continuous, fluent movements of fine, deeply weathered clay, saturated with water=> highly fluid, no cohesion

• AvalanchesAvalanches - rapid movements of snow and ice, rock and soil (debris avalanche) down a slope, very common in - rapid movements of snow and ice, rock and soil (debris avalanche) down a slope, very common in mountain areas.mountain areas.-dry avalanche = newly fallen snow falls off older snow – mainly in winter-dry avalanche = newly fallen snow falls off older snow – mainly in winter-wet avalanche = partially melted snow (triggered by skiing) – in spring-wet avalanche = partially melted snow (triggered by skiing) – in spring

GlaciationGlaciation

• – – is formation of glaciers in certain areasis formation of glaciers in certain areas Many landforms are results of glacial erosion and deposition.Many landforms are results of glacial erosion and deposition.

• 2 main phases2 main phases::cold periods – glacial – ice advanced southwardscold periods – glacial – ice advanced southwardswarm periods – interglacial – ice retreated northwardswarm periods – interglacial – ice retreated northwards

• Accumulation of iceAccumulation of ice – when a mass of ice is formed in a valley – – when a mass of ice is formed in a valley – formation of a glacierformation of a glacier

It can flow slowly downhill because of influence of gravity. E.g It can flow slowly downhill because of influence of gravity. E.g largest glaciers – in the Himalayas, Rocky mountains and the Alpslargest glaciers – in the Himalayas, Rocky mountains and the AlpsContinuous mass of ice covering a large land surface – ice sheet.Continuous mass of ice covering a large land surface – ice sheet.

Glacier as a systemGlacier as a system • Inputs:Inputs:

Precipitation, meltwater, sunlight, frost shaterring Precipitation, meltwater, sunlight, frost shaterring sedimentssediments

• Processes:Processes:Storage of glacier iceStorage of glacier ice

• OutputOutput::Meltwater, ice, rock debris, water(gas)Meltwater, ice, rock debris, water(gas)

• A glacier moves into warmer areas where the ice is melt – 2 A glacier moves into warmer areas where the ice is melt – 2 parts:parts:Zone of accumulationZone of accumulation(inputs>outputs) – glacier is growing, (inputs>outputs) – glacier is growing, snowfall>meltingsnowfall>melting

Zone of abalationZone of abalation (outputs>inputs)- glacier is shrinking and (outputs>inputs)- glacier is shrinking and retreating, melting>accumulationretreating, melting>accumulation

Glacial erosion and transportGlacial erosion and transport• Cold polar glaciersCold polar glaciers - move very slowly - move very slowly

• Warm, temperate glaciersWarm, temperate glaciers – move faster because meltwater helps to reduce the – move faster because meltwater helps to reduce the frictional forcefrictional force

• Glaciers can transport large amounts of rock debris – Glaciers can transport large amounts of rock debris – morainemoraine - can be brought:- can be brought:on the surface of the glacieron the surface of the glacierwithin the glacierwithin the glacieralong the glacieralong the glacier

• CorrieCorrie – semi-circular, steep-side basin cut into the side of a mountain or at the head – semi-circular, steep-side basin cut into the side of a mountain or at the head of a valley.of a valley.

• Corrie lake(tarn)Corrie lake(tarn)- glacier that has come into valley and interglacial period it melted - glacier that has come into valley and interglacial period it melted – only water remained – glacial lakes– only water remained – glacial lakes

• Pyramid peakPyramid peak – 3-4 corries cutting back on each other – 3-4 corries cutting back on each other

• U-shaped valleyU-shaped valley – created by a glacier moving downslopes – created by a glacier moving downslopes

• Hanging valleyHanging valley – tributary glaciers flow into the main larger one. After malting – tributary glaciers flow into the main larger one. After malting these glaciers leave the valley hanging above themthese glaciers leave the valley hanging above them

LandformsLandforms

• DrumlinsDrumlins – egg-shaped hills, formed under the glacuier by – egg-shaped hills, formed under the glacuier by ice that has moulded boulder clayu into this distinctive shapeice that has moulded boulder clayu into this distinctive shape

• EskersEskers – long ridges of deposited material, formed by – long ridges of deposited material, formed by deposition from meltwater streams which flow under the ice.deposition from meltwater streams which flow under the ice.

• ErraticsErratics – boulders transported over a long distance and – boulders transported over a long distance and deposited by glaciers.deposited by glaciers.

• KamesKames – small mounds of debris within ice, after thawing – small mounds of debris within ice, after thawing that dropped on the groundthat dropped on the ground

• Kettle holesKettle holes – detached blocks of ice, after melting water5 – detached blocks of ice, after melting water5 is in a hollow and could be lost by evaporation an infiltrationis in a hollow and could be lost by evaporation an infiltration

• Outwash plainsOutwash plains – as meltwater streams flow away from the – as meltwater streams flow away from the glacier, they begin to sort out material and deposit their load.glacier, they begin to sort out material and deposit their load.