Grade 10 4th Quarter Geography Notes PDF

1 Grade 10 4th QUARTER Geography Notes MASS WASTING DEFINITION OF MASS WASTINg Is the movement ( sliding, falling, creeping, or flowing ) of rock materials from one place to another under the influence of gravity. https:...

1 Grade 10 4th QUARTER Geography Notes MASS WASTING DEFINITION OF MASS WASTINg Is the movement ( sliding, falling, creeping, or flowing ) of rock materials from one place to another under the influence of gravity. https://www.internetgeography.net/topics/what-is-mass-movement FACTORS AFFECTING MASS WASTING Human activities Nature and weight of materials Presence of lubricating moisture. Presence of vegetation TYPES OF MASS WASTING A.) Soil creep : Is the downward movement of soil materials down a gentle slope with the aid of water. Alternate wetting and drying ; heating and cooling are factors that promote soil creep.It is noticed when fences or trees bend towards the direction of soil movement. B.) SOIL FLOW : Is when heavy rainfall turns the soil into a semi-liquid state causing the soil to flow as Mud flow or Soil flow. C.) ROCKS FALL : Is the most rapid mass wasting of all. This is the falling of a large mass of rocks from a steep cliff. The repeated rock fall of broken rocks which collect at the base of the slope is called (TALUS mound ).  2 D.) LANDSLIDE : Is the movement of large rock debris over underlying weak rocks. 1. Landslides are caused by 2. Water down a steep slope. 3. River under-cut a steep slope. 4. The pull of gravity. 5. Earthquakes or volcanoes 6. Man activities. FORM OF LANDSLIDE · Slumping · Sliding SLUMPING - Is very common where permeable rock layers overlies impermeable strata such as clay.. SLIDING - Is the downward movement of materials flowing down a steep slope. EFFECTS OF MASS WASTING · Leads to loss of farmlands. · Results of displacement of settlements. · Causes disruption of the transportation network.. · Leads to tilting of electric and telephone poles. · Causing the damming of rivers. · Leads to soil fertility  3 AGENTS MODIFYING LANDFORMS Agents modifying landforms are rivers, glaciers, waves, and winds. RIVERS Landscape River scenery drawing | Very Easy Drawing Tutorial Rivers are running water or streams in the channel of banks. Rivers are one of the important agents of denudation. Rivers are involved in erosion, transportation, and deposition of materials. TERMS ASSOCIATED WITH RIVERS Source of a river. Course of a river Mouth of a river River basin or catchment area. Watershed or water divide. Tributaries River energy RIVER ENERGY - refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the river velocity. River Channels https://www.youtube.com/results?search_query=Diagrams+of+river+channel  4 FACTORS AFFECTING THE VELOCITY OF A RIVER The volume of water released The slope of the river valley. The shape of the river valley The amount and size of materials STAGES OF A RIVER A river has three main parts or stages. They are upper, middle and lower. THE UPPER OR YOUNG COURSE/STAGE Is the beginning or source of a river. Is found around highland/mountain areas. It has steep sides Dominant river flows swiftly down steep slopes Dominant work is vertical erosion. THE MIDDLE OR MATURE COURSE/STAGE OF A RIVER Lateral erosion is dominant ( over vertical erosion ) Widening of river valley Wide V-Shape valley Increase in water volume.  5 THE LOWER OR OLD COURSE/STAGE OF A RIVER · Deposition is the main work · Active lateral erosion · Water volume increase · Gradient of river valley lowers. · Drastic reduction in river speed. RIVER EROSION Refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the velocity. FACTORS AFFECTING THE VELOCITY OF A RIVER A.) The volume of water released B.) The slope of the river valley. C.) The shape of the river valley D.) The amount and size of materials. RIVER EROSION The load or materials carried by a river are the main agents of erosion. The erosive work of a river consists of four processes.  6 They are: 1.) HYDRAULIC ACTION Is where the water enter into cracks and cavities causing them to enlarge. 2.) CORRASION Is the wearing of the sides and floor of the river valley by sand, pebbles, silts and boulders which are being transported. 3.) ATTRITION Is the wearing down of the loads as they collide with the valley and one another. Example: Large boulders are broken down into small pieces of pebbles. 4.) SOLUTION Is the chemical action of water on materials. Example: Rock salt is dissolve this way. PROCESSES OF RIVER TRANSPORTATION A river transports it loads in four ways or processes. They are : 1.) SOLUTION Some materials dissolve in water and are carried to the lower course. 2.) SUSPENSION Is the carriage of larger particles suspended in the water as it flows. 3.) SALTATION  7 Is the bouncing of materials either on the surface or at the floor of the river. 4.) TRACTION Is the dragging and rolling of the river load along the river bed. OX-BOW LAKE MODE OF FORMATION · Formed in the lower of a river where there is pronounced meanders. · As the waters in the river flow, there is erosion on the concave side and deposition on the convex bank. CHARACTERISTICS OF OX-BOW LAKE · Feature of the lower course of a river. · Occurs in marshy areas. · Has horse-shoe shape · Has a shallow convex bank. · Has a deep concave bank. · It is also called Bayous/Cut-offs.  8 DELTA DELTA - is a fan-shaped alluvial plain formed as a result of deposition by river. MODE OF FORMATION OF DELTA · Formed from the deposition of sediments · The absence of strong ocean current · Presence of sediments at the estuary. FAVOURABLE CONDITION FOR THE FORMATION OF DELTA · Active vertical and lateral erosion. · Tideless coast or sheltered coast. · Shallow sea adjoining the delta. · No large lakes in the river course ( sediment removal ) · No strong current at right angle to the river. CHARACTERISTICS OF RIVER DELTA · Found at the lower course  9 · Occurs in swampy areas. · Has seaward expansion of river flood plain · Composed of alluvium · Has distributaries. · Has many shapes. TYPES OF DELTA There are three types of Delta. They are : 1.) ARCUATE DELTA · Consists of both coarse and fine sediments. · Has an inverted cone shape. · It crosses many distributaries. 2.) BIRD FOOT DELTA · Consists of fine materials called silts. · Has several distributaries like bird foot. · Extend into the sea. 3.) ESTUARINE DELTA · Formed when there is partial submerged in coastal waters. · Direct flow of water in the sea.  10 RIVER REJUVENATION A river is said to be rejuvenated when it is given a new lease of life or being young again. Example: an extra power of erosion. IMPORTANCE OF DELTA TO MAN · Provides good agricultural land. · It is good for fishing. · Good for petroleum mining. ACTION OF GLACIERS IN TEMPERATE REGIONS Glacier action is an important agent of Erosion, Transportation and Deposition. It is common in mountainous and temperate regions. TERMS ASSOCIATED WITH GLACIERS 1.) ICE Refers to solid form of water resulting from freezing temperature persistently below 00 C.  11 2.) GLACIER Moving ice or very large sheet of ice. 3.) GLACIATION Refers to the wearing away of the earth surface by glacier. 4.) SNOW Refers to freezing water vapour which falls in the form of crystals. 5.) SNOW LINE Is the lower limit of perpetual snow cover on a mountain. 6.) SNOW FIELD Refers to the region or area permanently under snow cover. ACTION OF GLACIER EROSION There are three ways by glacier carried out erosion. They are; 1.) SAPPING Is where rocks are broken up due to alternate freezing. The thawing of water at the bottom of cracks between a mass of ice and the sides and floor of a valley. 2.) PLUCKING Is the tearing away of blocks of rocks which have been frozen on the sides or bottom of a glacier.  12 3.) ABRASION Is the wearing away of rocks beneath a glacier by the scoring action. FEATURES OF GLACIER EROSION IN HIGHLAND AREAS 1.) STRIATION Are marks or stretches left on rocks over which glacier passes. 2.) CORRIES OR CIRQUE Is a deep and rounded hollow or depression with steep sides. It also results from plucking. After the ice has moved it forms Cirque lake ( Arm-chair-shape hollow ). 3.) ARETE Is the feature formed from when two Corries out back opposite sides of the same mountain. It is a Knife-edged ridge. 4.) PYRAMIDAL PEAK Is a pinnacle shaped. Is a feature formed when three or more Corries cut back on the same mountain. 5.) BERGSCHRUND Is formed at or near the head of glacial. It is a deep and vertical crack. Small scale crack also develop where glacial negotiates a bend along it valleys. Such small cracks are called Crevasses. 6.) TROUGH OR U-SHAPED VALLEY Is a wide , flat floor with very steep side.  13 7.) MORAINES Are made up of pieces of rocks that are shattered by frost action. FEATTURES OF GLACIAL EROSION IN LOWLAND A. ROCHE MOUTONNEE Are resistant residual rock structure. The surface is always rough. B. CRAIG AND TAIL Is a mass of hard rock which slopes on the upstream side and that protect the softer leeward slope from erosion. FEATURES OF GLACIAL DEPOSITION IN LOWLANDS 1.) BOULDER CLAY Is the ground moraine of the glacial. 2.) ERRATICS Are transported rock fragments. 3.) DRUMLINS Are swarms of oval, elongated whale-back hummocks. The shape of drumlin are better describe as “Basket of Egg”. 4.) ESKERS Are long, narrow and winding ridges of sand and gravel.  14 5.) TERMINAL MORAINES Are made up of boulders deposited at the edge of the ice sheet. 6.) OUTWASH PLAIN Is wide area of sand and gravel. ACTION OF WAVES IN COASTAL LAND Wave action is an important agent of erosion, transportation and deposition of materials confined to the coast of seas and oceans. TERMS ASSOCIATED WITH WAVES 1.) WAVES Is the turbulent movement of water as a result of wind moving over the sea or ocean water. 2.) TIDE Is the alternate rise and fall of the surface water of the sea ( twice a day ). 3.) CURRENT  15 Is the movement of the surface water of the ocean in a definite direction. 4.) COAST Is the meeting point between the land and the sea. 5.) SHORE Is the land portion lying between high water and low water. 6.) BEACH Refers to the materials deposited on the shore. It is usually sandy materials. 7.) SWASH Is the water that sucks back and retreats after wash. 8.) UNDERTOW Is the water which flows near the bottom away from the shore. MECHANISM OF WAVE EROSION There are four mechanisms of waves erosion. They are ; Corrosion, Attrition, Hydraulic action and Solvent action, See river erosion for explanation. FEATURES PRODUCED BY WAVE EROSION  16 1.) CAPE AND BAY BAY is usually a space or land which contains water and could be used as harbor. Cape is a piece of land projecting into the sea it is associated with hard rock. A cape is times called Promontories or Headlands. 2.) CLIFFS Are steep rock faces adjoining the coast. 3.) COASTAL CAVE - Is formed by marine erosion. - Has a Arch-shaped - It may contain Bow-holes or Geo. 4.) ARCH Is the joining of two caves. 5.) STACK - Is the seaward portion of the promontory. - Is the collapsed arch of joined caves roof. 6.) STUMP Is the visible portion of a seriously eroded stack above sea level. 7.) GEO Is a narrow hole which results when a cliff is cut by a wave. 8.) GLOUP  17 Is formed by wave erosion on a coastal cliff. Spray water in the cave enlarges a vertical joint in the roof resulting in loose blocks falling because of hydraulic action. FEATURES OF COASTAL DEPOSITION BEACHES Are made up of sand and gravels. Are formed when sand and gravels loosened from the land. They are depositional features SAND SPLITS Are ridges of sand and gravels formed by long shore drift across inlet. MARINE DUNES OR DUNE BELTS Is the movement of large amount of coastal sand by onshore winds with large force. SAND BAR  18 Formed by wave deposition in shallow sandy waters. Is a built-up of sand which is at times covered by water at high tide and exposed at low tide.  19 DESERT LANDFORMS DEFINITION OF DESERT Desert is a barren land that receives little precipitation with poor living condition to support plant and animal lives. ARID OR ARIDITY – Is the place having little or rain to support vegetation. Most desert or arid areas in the world lie between 150 and 300 north and south of the equator. The world largest cold desert is Antarctica. The world largest hot desert is Sahara The Dries or rainless desert in the world is Atacama The only continent with no desert is Europe. The desert plants without leaves are called Xerophytes. The desert plants with longest roots are called Phreatophytes. CAUSES OF ARIDITY These are factors that influence aridity in desert areas. · Interior location or continentality. · Cold ocean current  20 · Rain shadow effects or leeward location. CHARACTERISTICS OF DESERTS These are the appearances and description of deserts. They are: · Low precipitation or rainfall · High temperature · Absence of vegetation cover · High rate of evaporation · High rate of physical or mechanical weathering · Wind action is dominant · Presence of cold current · Internal drainage · Presence of landforms. TYPES OF DESERT LANDSCAPES 1.) SANDY OR ERG Is an undulating plain of desert with large amount of sand and sand dunes. It is produce by wind deposition. Example: Coastal sandy desert of Western Sahara. 2.) STONY OR REG  21 Is a desert surface covered with gravels, stones, boulders and pebbles. It is produced by daily temperature change or exfoliation process of weathering. Example: Kalahari desert in Africa. Example Hamada el Homra in Libya 3.) ROCKY OR HAMADA Is a produced by erosional process of deflation and abrasion. Is a desert surface covered with large stretches of bare rocks. 4.) BADLAND OR MOUNTAIN DESERT This desert landscape develops in arid region of sudden rainstorm. Examples: Ahaggar in Algeria and Badlands in Dakota ( USA ). FUNCTIONS OR ROLES OF WIND IN THE DESERT AREAS. Wind perform three functions in desert areas. They are; erosion, transportation and deposition. ACTIONS OR PROCESSES OF WIND EROSION IN DESERT AREAS Wind erosion is carried out in the following ways. They are;  22 1.) DEFLATION Is the lifting and blowing away of loose sand and pebbles by wind. The lowering of the land surface to form large depression called Deflation hollows. Examples: Qattara Salt Lake Depression in Egypt. 2.) ABRASION OR CORRASION Is the process of sand particles wearing away rock surfaces as they are blown by wind. Examples: Rock pedestal, Zeugens and Yardang. 3.) ATTRITION Is the process of wind borne particles colliding with each other resulting in the wearing away of each other. DIFFERENCES BETWEEN DEFLATION AND ABRASION · Deflation is blowing away of loose rock waste whilst abrasion is the hauling of rocks against rock surfaces. · Deflation usually results in lowering land surface whilst abrasion is most effective at the rock base. · Deflation is associated with wind only whilst abrasion is associated with wind, water and wave. · Deflation occur only in arid and semi-arid regions whilst abrasion occurs everywhere.  23 WHY WIND EROSION IS MORE ACTIVE IN ARID AREAS THAN HUMID REGIONS · Absence of vegetation cover · Presence of friable and light soil · Low rainfall LANDFORMS ORODUCED BY WIND EROSION IN DESERT REGIONS 1.) VENTIFACTS Is a faceted or flattered rock with smooth surface and sharp edges by wind-blown sand in desert area. CHARACTERISTICS OF VENTIFACTS OR DREIKANTERS - They are found in hot desert regions. - They are features of wind sand-blast. - They may have one or more flat face or facet with sharp edges. - Examples: White desert near Farafar Oasis in Egypt 2.) ZEUGENS Is a tabular mass of rocks having alternate bands of hard rock lying over soft rock to form landscapes of ridges and furrows.  24 MODE OF FORMATION Is formed when wind abrasion wears the mass rock into a ridge and furrow landscape. Mechanical weathering starts the formation by opening up joints of the surface of hard rocks. CHARACTERISTISTICS OF ZEUGENS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have horizontal bands of hard and soft rocks. - They are tabular masses of rocks separated by dee furrow. - They are 10 – 30 meters in height. - Examples are found in the Sahara, Atacama and Turkey. 3.) YARDANGS Are over hanging steep-sided ridges separated from each other by long narrow furrows. MODE OF FORMATION Are formed when the hard and soft rocks in vertical bands are aligned in the direction of the prevailing winds. Note that the soft rocks are wear away by wind abrasion causing corridor of long narrow softer rocks. The hard rocks are Yardangs.  25 CHARACTERISTICS OF YARDANGS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have vertical bands of hard and soft rocks. - They lie parallel to the prevailing winds - They are low overhanging ridges with steep sides. - Examples are found in Komombo in Egypt and Salah in Algeria. 4.) ROCK PEDESTAL Is a Mushroom shaped pillar of rock with irregular sides projecting above the surrounding desert plain. MODE OF FORMATION Are formed by wind abrasion on an alternate horizontal layers of hard and soft rocks. CHARACTERISTICS OF ROCK PEDESTAL - They are found in hot desert regions. - They are features of wind sand-blast. - They are mushroom-shaped rock. - They have steep and irregular faces. - They are 10 – 15 meters in height.  26 - Examples: Mushroom rocks in Wuling-jirapa, Ghana. PROCESSES OF WIND TRANSPORTATION IN DESERT REGIONS There are three processes of wind transportation. They are; 1.) SUSPENSION Is the process whereby wind lift fine particles of sand or silt to some few meters above the ground and carries from area to another. 2.) TRACTION Is a process whereby large fragments like boulders which cannot be lifted are rolled or dragged on the surface of the land from one area to another by wind. 3.) SALTATION Is a process whereby wind causes sand grains or coarse particles to move from one place to another in a series of hops or bounces. LANDFORMS PRODUCED BY WIND DEPOSITION IN DESERT AREAS Wind deposit the load it carries when it come into contact obstacles like rock, mound and vegetation. Landforms or features produced by wind deposition include: 1.) BARCHAN OR SAND DUNES  27 Is a crescent-shaped sand dune with two horn lying right angle to the direction of the wind. CHARACTERISTICS OF BARCHAN - They are found in desert like Sahara - They have crescent or half-moon shaped dunes - They have gentle and convex windward side - They have steep and concave leeward side. 2.) SEIF DUNES OR LONGITUDINAL DUNES Is a long, narrow and steep sided sand dune lying parallel to the prevailing wind. MODE OF FORMATION - Formed by wind eroding sand dunes - Formed by the central breaching of barchan - Formed by the emerging of several barchans. CHHARACTERISTICS OR DESCRIPTION SEIF DUNES - They are features of sand depositions - They have long and narrow ridges - They have steep sides  28 - They lie parallel to each other. 3.) LOESS Is the deposit of fine silt or dust particles transported by wind beyond desert boundaries. CHARACTERIISTICS OF LOESS - They are features of sand deposition - They consists of fertile and fine-grained soil. - They have porous and well-drained landscapes - They are found in desert regions WATER ACTION OR FLUVIAL EROSION IN DESERT AREAS Running water or river is an important agent of producing landforms in desert areas. SOURCES OF RUNNING WATER IN DESERT AREAS - Flash floods - Foreign Rivers - Melting snow from mountains to temperate highlands - Past fluvial action PROCESSES OF WATER OR FLUVIAL EROSION IN DESERT AREAS  29 1.) HYDRAULIC ACTION Is the process whereby running water removes materials like sand, silt and gravels. This process also involves river surging into cracks of rocks along the valley floor of the river. 2.) ABRASION Is the process whereby the loose materials carried by the river are used to wear away the sides and beds of the valley floor. 3.) ATTRITION Is the process in which eroded materials being carried knock against each other and the bed – breaking up into smaller or rounded particles. 4.) SOLUTION Is the process whereby acidic water flows over soluble rocks like limestone. The acidic water causes the rock to dissolve and carried away as solution. LANDFORMS OF WATER OR RIVER EROSION IN DESERT AREAS These are erosional features resulting from water or fluvial. 1.) WADI - Is a steep-sided valley with flat floor in desert areas.  30 - It is usually dry except during torrential rainfall. - Formed by erosional action of torrential rainfall which produces flashflood. CHARACTERISTICS OF WADI - They are mostly found in arid and semi-arid regions. - They have steep sides and flat floor - They are features of erosional action of running water. - Their floor contain weathered materials or debris. - Examples Wadi al Masid in Libya and Wadi Abbad in Egypt 2.) CANYON - Is a deep, narrow trench with steep - sided valley{ V-shaped } - Canyon is formed in highlands or upland desert areas by the action of river erosion. The erosive power cut down the surface of the soft rock thereby widening the walls and floor of the valley. The V-shaped valley across the horizontal band of hard and soft rocks is called Canyon. CHARACTERISTICS OF CANYON - They are found in desert areas. - They are features of river erosion. - They have deep and narrow valleys. - They are in high plateau and mountainous areas. - They have deep walls and marked by irregular gradient.  31 - Examples: Fish river Canyon in Namibia ; Grand Canyon in Arizona-USA. 3.) PENEPLAIN - Is a low undulating land surface which is mostly a plain resulting from continued denudation. - Formed by the action of river erosion. River erodes the highland or uplands and divides them into individual plateaux or apartments with deep valleys of steep slopes. CHARACTERISTICS OF PENEPLAIN - They are found in upland desert areas. - They are features of river erosion. - They are extensive undulating plains. - Example: Peneplain of Mauritania 4.) PEDIMENT - Is a gentle sloping erosion surface or plain with sediments at the base of a receding mountain front. - Formed at base of desert uplands or mountains by action of river erosion, torrential rainfall or sheet floods. - When two or more Pediments join together{ coalsce } they formed PEDIPLAIN. CHARACTERISTICS OF PEDIMENTS - They are found in uplands desert areas. - They are features of river erosion. - They have gently sloping surface.  32 - They are slightly concave with the sloping angle ranging from 0.50 - 70 - Examples are found in the Sahara and Mojave Deserts. 5.) INSELBERGS OR BORNHADTS - They are isolated residual hills with rounded top and steep sides rising abruptly from the surrounding plains in desert regions. - Formed from semi-arid and arid regions by the action running water or wind erosion. CHARACTERISTICS OF INSELBERGS - They are found in semi-arid and arid areas. - They features of rainfall and running water. - Their height mat rise up to about 300 meters high. - Most inselbergs are made up of granite gneiss. - Examples: Shai and Krobo Hills in Ghana; and Brangberh Hills in Namib Desert. 6.) MESAS OR BUTTES - They are flat table-like and steep sided landmass with resistant horizontal top layer underlain by layers of soft rocks. - When the sizes of mesas are reduced to small isolated hills, they become Buttes. - They are formed by the actions of extreme temperature, running water, rainfall and wind erosion on alternate bands of hard and soft rocks.  33 CHARACTERISTICS OF MESAS AND BUTTES - They are found in semi-arid and arid areas. - They are products of running water, rainfall, or wind action. - They are flat-like land masses. - They are isolated flat-topped hills. - Examples are found in Sahara and Kalahari Deserts. DEPOSITIONAL LANDFORMS OF WATER OR RIVER ACTION IN DESERT AREAS. 1.) BAJADA - Is broad gentle sloping sediments bordering the foot of a mountain range by the coalescing of several alluvial fans. - They are formed by river deposition in desert. several rivers flow over linear mountain range picking sediments with other materials, as the river flow in areas of flat plains at the mountain base, it speed and energy reduce allowing deposition to take place. - Therefore, Bajada are two or more alluvial fans at the foot of the linear mountain range gradually coalesced or emerged together to form a broad gentle undulating slope with smooth surfaces. CHARACTERISTICS OF BAJADA - They are found in desert areas. - They are features of river deposition. - They are fairly gentle undulating slope.  34 - They have smooth surfaces - The slope is less than 70 2.) PLAYA OR SALINA - Is a temporay inland drainage basin with shallow lake of fluctuating volume encircled by a mud sheet. - It is simply a Temporary Salt Lake found in arid and semi-arid areas. CHARACTERISTICS OF PLAYA OR SALINA - They are found in desert areas. - They are features of desert river deposition. - They contain temporary salt lake. - They are usually found at the bottom of the basin or depression. - Examples: Playas in Algeria and Salinas of Lake Magadi of Kenya. - QUESTIONS FOR CLASS ASSESSMENT 1.) Temporary Salt Lake in arid and semi-arid regions are called a. Ventifacts c. Oasis b. Mesas d. Playa 2.) Which of the below landforms formed by Fluvial action is associated with Arizona, U.S.A. ?  35 a. Canyon c. Peneplain b. Wadi d. bajada 3.) “They are crescentric or moon-shaped and occur individually or group”. The above description refers to a. Yardangs c. Barchans b. Seifs d. Pediment 4.) The plains formed when the slopes of mountains are worn back in desert area by mechanical weathering is called a. Pediplain c. Deflation plain b. Alluvial plain d. Outwash plain 5.) In an Oasis, water is derived from a. Bajada c. underground b. Rainfall d. playa MASS WASTING DEFINITION OF MASS WASTING  36 Is the movement ( sliding,, falling, creeping, or flowing ) of rock materials from one place to another under the influence of gravity. FACTORS AFFECTING MASS WASTING · Gradient of the slope. · Human activities. · Nature and weight of materials. · Presence of lubricating moisture. · Presence of vegetation · TYPES OF MMASS WASTING A.) Soil creep Is the downward movement of soil materials down a gentle slope with the aid of water. Alternate wetting and drying ; heating and cooling are factors that promote soil creep. It is noticed when fence or tree bend towards the direct of soil movement. B.) SOLIFLUCTION OR SOIL FLOW Is when heavy rainfall turn the soil into semi-liquid state causing the soil to flow as Mud flow or Soil flow. C.) ROCKS FALL Is the most rapid mass wasting of all. This is the falling of large mass of rocks from a steep cliff.  37 The repeated rock fall of broken rocks which collect at the base of the slope is called TALUS ( mound ). D.) LANDSLIDE Is the movement of large rock debris over underlying weak rocks. Landslides are caused by · Water down steep slope. · River under-cut a steep slope. · The pull of gravity. · Earthquakes or volcanism · Man activities. FORM OF LANDSLIDE · Slumping · Sliding SLUMPING - Is very common where permeable rock layers overlies impermeable strata such ass clay.. SLIDING - Is the downward movement of materials flowing down steep slope. EFFECTS OF MASS WASTING · Leads to loss of farmlands. · Results to displacement of settlements. · Causes disruption of transportation network.. · Leads to tilting of electric and telephone poles.  38 · Causing the damming of river. · Leads to soil fertility AGENTS MODIFYING LANDFORMS Agents modifying landforms are rivers, glaciers, waves, and winds. RIVERS Rivers are running water or streams in the channel of banks. Rivers is one of the important agents of denudation. Rivers are involved in erosion, transportation, and deposition of materials. TERMS ASSOCIATED WITH RIVERS · Source of a river. · Course of a river · Mouth of a river · River basin or catchment area. · Watershed or water divide.  39 · River regime · Confluence of a river · Tributaries · Distributaries · River energy RIVER ENERGY - refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the river velocity. FACTORS AFFECTING THE VELOCITY OF A RIVER A.) The volume of water released B.) The slope of the river valley. C.) The shape of the river valley D.) The amount and size of materials. STAGES OF A RIVER A river has three main parts or stages. They are upper, middle and lower.  40 THE UPPER OR YOUNG COURSE/STAGE · Is the beginning or source of a river. · Is found around highland/mountain areas. · It has steep sides · Dominant river flows swiftly down steep slopes · Dominant work is vertical erosion. FEATURES OF UPPER OR YOUNG COURSE OF A RIVER · V-Shape valley · Gorge · River capture · Rapid and cataracts · Waterfalls THE MIDDLE OR MATURE COURSE/STAGE OF A RIVER · Lateral erosion is dominant ( over vertical erosion ) · Widening of river valley · Wide V-Shape valley · Presence of Bluff, River cliff, Meanders, Terraces.  41 · Increase in water volume. · Increase in river load. · Transportation is the river load. · Little deposition. FEATURES OF MIDDLE OR MATURE COURSE/ STAGE OF A RIVER · Wide V-Shape valley · Meanders · River cliff and Slip-off slopes · Interlocking spur THE LOWER OR OLD COURSE/STAGE OF A RIVER · Deposition is the main work · Active lateral erosion · Water volume increase · Gradient of river valley lowers. · Drastic reduction in river speed.  42 FEATURES OF THE LOWER OR OLD COURSE/STAGE OF A RIVER · Flood plain · Levees · Ox-bow lake · Braided river · Delta RIVER EROSION Refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the velocity. FACTORS AFFECTING THE VELOCITY OF A RIVER A.) The volume of water released B.) The slope of the river valley. C.) The shape of the river valley D.) The amount and size of materials. RIVER EROSION  43 The load or materials carried by a river are the main agents of erosion. The erosive work of a river consists of four processes. They are: 1.) HYDRAULIC ACTION Is where the water enter into cracks and cavities causing them to enlarge. 2.) CORRASION Is the wearing of the sides and floor of the river valley by sand, pebbles, silts and boulders which are being transported. 3.) ATTRITION Is the wearing down of the loads as they collide with the valley and one another. Example: Large boulders are broken down into small pieces of pebbles. 4.) SOLUTION Is the chemical action of water on materials. Example: Rock salt is dissolve this way. PROCESSES OF RIVER TRANSPORTATION A river transports it loads in four ways or processes. They are : 1.) SOLUTION Some materials dissolve in water and are carried to the lower course.  44 2.) SUSPENSION Is the carriage of larger particles suspended in the water as it flows. 3.) SALTATION Is the bouncing of materials either on the surface or at the floor of the river. 4.) TRACTION Is the dragging and rolling of the river load along the river bed. OX-BOW LAKE MODE OF FORMATION · Formed in the lower of a river where there is pronounced meanders. · As the waters in the river flow, there is erosion on the concave side and deposition on the convex bank. CHARACTERISTICS OF OX-BOW LAKE · Feature of the lower course of a river. · Occurs in marshy areas. · Has horse-shoe shape  45 · Has a shallow convex bank. · Has a deep concave bank. · It is also called Bayous/Cut-offs. DELTA DELTA - is a fan-shaped alluvial plain formed as a result of deposition by river. MODE OF FORMATION OF DELTA · Formed from the deposition of sediments · The absence of strong ocean current · Presence of sediments at the estuary. FAVOURABLE CONDITION FOR THE FORMATION OF DELTA · Active vertical and lateral erosion. · Tideless coast or sheltered coast. · Shallow sea adjoining the delta. · No large lakes in the river course ( sediment removal ) · No strong current at right angle to the river.  46 CHARACTERISTICS OF RIVER DELTA · Found at the lower course · Occurs in swampy areas. · Has seaward expansion of river flood plain · Composed of alluvium · Has distributaries. · Has many shapes. TYPES OF DELTA There are three types of Delta. They are : 1.) ARCUATE DELTA · Consists of both coarse and fine sediments. · Has an inverted cone shape. · It crosses many distributaries. 2.) BIRD FOOT DELTA · Consists of fine materials called silts. · Has several distributaries like bird foot. · Extend into the sea. 3.) ESTUARINE DELTA · Formed when there is partial submerged in coastal waters.  47 · Direct flow of water in the sea. RIVER REJUVENATION A river is said to be rejuvenated when it is given a new lease of life or being young again. Example: an extra power of erosion. IMPORTANCE OF DELTA TO MAN · Provides good agricultural land. · It is good for fishing. · Good for petroleum mining. ACTION OF GLACIERS IN TEMPERATE REGIONS Glacier action is an important agent of Erosion, Transportation and Deposition. It is common in mountainous and temperate regions. TERMS ASSOCIATED WITH GLACIERS  48 1.) ICE Refers to solid form of water resulting from freezing temperature persistently below 00 C. 2.) GLACIER Moving ice or very large sheet of ice. 3.) GLACIATION Refers to the wearing away of the earth surface by glacier. 4.) SNOW Refers to freezing water vapour which falls in the form of crystals. 5.) SNOW LINE Is the lower limit of perpetual snow cover on a mountain. 6.) SNOW FIELD Refers to the region or area permanently under snow cover. ACTION OF GLACIER EROSION There are three ways by glacier carried out erosion. They are; 1.) SAPPING Is where rocks are broken up due to alternate freezing. The thawing of water at the bottom of cracks between a mass of ice and the sides and floor of a valley.  49 2.) PLUCKING Is the tearing away of blocks of rocks which have been frozen on the sides or bottom of a glacier. 3.) ABRASION Is the wearing away of rocks beneath a glacier by the scoring action. FEATURES OF GLACIER EROSION IN HIGHLAND AREAS 1.) STRIATION Are marks or stretches left on rocks over which glacier passes. 2.) CORRIES OR CIRQUE Is a deep and rounded hollow or depression with steep sides. It also results from plucking. After the ice has moved it forms Cirque lake ( Arm-chair-shape hollow ). 3.) ARETE Is the feature formed from when two Corries out back opposite sides of the same mountain. It is a Knife-edged ridge. 4.) PYRAMIDAL PEAK Is a pinnacle shaped. Is a feature formed when three or more Corries cut back on the same mountain. 5.) BERGSCHRUND  50 Is formed at or near the head of glacial. It is a deep and vertical crack. Small scale crack also develop where glacial negotiates a bend along it valleys. Such small cracks are called Crevasses. 6.) TROUGH OR U-SHAPED VALLEY Is a wide , flat floor with very steep side. 7.) MORAINES Are made up of pieces of rocks that are shattered by frost action. FEATTURES OF GLACIAL EROSION IN LOWLAND A. ROCHE MOUTONNEE Are resistant residual rock structure. The surface is always rough. B. CRAIG AND TAIL Is a mass of hard rock which slopes on the upstream side and that protect the softer leeward slope from erosion. FEATURES OF GLACIAL DEPOSITION IN LOWLANDS 1.) BOULDER CLAY Is the ground moraine of the glacial. 2.) ERRATICS Are transported rock fragments. 3.) DRUMLINS  51 Are swarms of oval, elongated whale-back hummocks. The shape of drumlin are better describe as “Basket of Egg”. 4.) ESKERS Are long, narrow and winding ridges of sand and gravel. 5.) TERMINAL MORAINES Are made up of boulders deposited at the edge of the ice sheet. 6.) OUTWASH PLAIN Is wide area of sand and gravel. ACTION OF WAVES IN COASTAL LAND Wave action is an important agent of erosion, transportation and deposition of materials confined to the coast of seas and oceans. TERMS ASSOCIATED WITH WAVES 1.) WAVES Is the turbulent movement of water as a result of wind moving over the sea or ocean water. 2.) TIDE  52 Is the alternate rise and fall of the surface water of the sea ( twice a day ). 3.) CURRENT Is the movement of the surface water of the ocean in a definite direction. 4.) COAST Is the meeting point between the land and the sea. 5.) SHORE Is the land portion lying between high water and low water. 6.) BEACH Refers to the materials deposited on the shore. It is usually sandy materials. 7.) SWASH Is the water that sucks back and retreats after wash. 8.) UNDERTOW Is the water which flows near the bottom away from the shore. MECHANISM OF WAVE EROSION There are four mechanisms of waves erosion. They are ; Corrosion, Attrition, Hydraulic action and Solvent action, See river erosion for explanation.  53 FEATURES PRODUCED BY WAVE EROSION 1.) CAPE AND BAY BAY is usually a space or land which contains water and could be used as harbor. Cape is a piece of land projecting into the sea it is associated with hard rock. A cape is times called Promontories or Headlands. 2.) CLIFFS Are steep rock faces adjoining the coast. 3.) COASTAL CAVE - Is formed by marine erosion. - Has a Arch-shaped - It may contain Bow-holes or Geo. 4.) ARCH Is the joining of two caves. 5.) STACK - Is the seaward portion of the promontory. - Is the collapsed arch of joined caves roof. 6.) STUMP Is the visible portion of a seriously eroded stack above sea level.  54 7.) GEO Is a narrow hole which results when a cliff is cut by a wave. 8.) GLOUP Is formed by wave erosion on a coastal cliff. Spray water in the cave enlarges a vertical joint in the roof resulting in loose blocks falling because of hydraulic action. FEATURES OF COASTAL DEPOSITION BEACHES Are made up of sand and gravels. Are formed when sand and gravels loosened from the land. They are depositional features SAND SPLITS Are ridges of sand and gravels formed by long shore drift across inlet. MARINE DUNES OR DUNE BELTS Is the movement of large amount of coastal sand by onshore winds with large force.  55 SAND BAR Formed by wave deposition in shallow sandy waters. Is a built-up of sand which is at times covered by water at high tide and exposed at low tide.  56 DESERT LANDFORMS DEFINITION OF DESERT Desert is a barren land that receives little precipitation with poor living condition to support plant and animal lives. ARID OR ARIDITY – Is the place having little or rain to support vegetation. Most desert or arid areas in the world lie between 150 and 300 north and south of the equator. The world largest cold desert is Antarctica. The world largest hot desert is Sahara The Dries or rainless desert in the world is Atacama The only continent with no desert is Europe. The desert plants without leaves are called Xerophytes. The desert plants with longest roots are called Phreatophytes. CAUSES OF ARIDITY  57 These are factors that influence aridity in desert areas. · Interior location or continentality. · Cold ocean current · Rain shadow effects or leeward location. CHARACTERISTICS OF DESERTS These are the appearances and description of deserts. They are: · Low precipitation or rainfall · High temperature · Absence of vegetation cover · High rate of evaporation · High rate of physical or mechanical weathering · Wind action is dominant · Presence of cold current · Internal drainage · Presence of landforms. TYPES OF DESERT LANDSCAPES 1.) SANDY OR ERG Is an undulating plain of desert with large amount of sand and sand dunes. It is produce by wind deposition. Example: Coastal sandy desert of Western Sahara.  58 2.) STONY OR REG Is a desert surface covered with gravels, stones, boulders and pebbles. It is produced by daily temperature change or exfoliation process of weathering. Example: Kalahari desert in Africa. Example Hamada el Homra in Libya 3.) ROCKY OR HAMADA Is a produced by erosional process of deflation and abrasion. Is a desert surface covered with large stretches of bare rocks. 4.) BADLAND OR MOUNTAIN DESERT This desert landscape develops in arid region of sudden rainstorm. Examples: Ahaggar in Algeria and Badlands in Dakota ( USA ). FUNCTIONS OR ROLES OF WIND IN THE DESERT AREAS. Wind perform three functions in desert areas. They are; erosion, transportation and deposition. ACTIONS OR PROCESSES OF WIND EROSION IN DESERT AREAS  59 Wind erosion is carried out in the following ways. They are; 1.) DEFLATION Is the lifting and blowing away of loose sand and pebbles by wind. The lowering of the land surface to form large depression called Deflation hollows. Examples: Qattara Salt Lake Depression in Egypt. 2.) ABRASION OR CORRASION Is the process of sand particles wearing away rock surfaces as they are blown by wind. Examples: Rock pedestal, Zeugens and Yardang. 3.) ATTRITION Is the process of wind borne particles colliding with each other resulting in the wearing away of each other. DIFFERENCES BETWEEN DEFLATION AND ABRASION · Deflation is blowing away of loose rock waste whilst abrasion is the hauling of rocks against rock surfaces. · Deflation usually results in lowering land surface whilst abrasion is most effective at the rock base. · Deflation is associated with wind only whilst abrasion is associated with wind, water and wave.  60 · Deflation occur only in arid and semi-arid regions whilst abrasion occurs everywhere. WHY WIND EROSION IS MORE ACTIVE IN ARID AREAS THAN HUMID REGIONS · Absence of vegetation cover · Presence of friable and light soil · Low rainfall LANDFORMS ORODUCED BY WIND EROSION IN DESERT REGIONS 1.) VENTIFACTS Is a faceted or flattered rock with smooth surface and sharp edges by wind-blown sand in desert area. CHARACTERISTICS OF VENTIFACTS OR DREIKANTERS - They are found in hot desert regions. - They are features of wind sand-blast. - They may have one or more flat face or facet with sharp edges. - Examples: White desert near Farafar Oasis in Egypt 2.) ZEUGENS  61 Is a tabular mass of rocks having alternate bands of hard rock lying over soft rock to form landscapes of ridges and furrows. MODE OF FORMATION Is formed when wind abrasion wears the mass rock into a ridge and furrow landscape. Mechanical weathering starts the formation by opening up joints of the surface of hard rocks. CHARACTERISTISTICS OF ZEUGENS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have horizontal bands of hard and soft rocks. - They are tabular masses of rocks separated by dee furrow. - They are 10 – 30 meters in height. - Examples are found in the Sahara, Atacama and Turkey. 3.) YARDANGS Are over hanging steep-sided ridges separated from each other by long narrow furrows. MODE OF FORMATION  62 Are formed when the hard and soft rocks in vertical bands are aligned in the direction of the prevailing winds. Note that the soft rocks are wear away by wind abrasion causing corridor of long narrow softer rocks. The hard rocks are Yardangs. CHARACTERISTICS OF YARDANGS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have vertical bands of hard and soft rocks. - They lie parallel to the prevailing winds - They are low overhanging ridges with steep sides. - Examples are found in Komombo in Egypt and Salah in Algeria. 4.) ROCK PEDESTAL Is a Mushroom shaped pillar of rock with irregular sides projecting above the surrounding desert plain. MODE OF FORMATION Are formed by wind abrasion on an alternate horizontal layers of hard and soft rocks. CHARACTERISTICS OF ROCK PEDESTAL - They are found in hot desert regions. - They are features of wind sand-blast.  63 - They are mushroom-shaped rock. - They have steep and irregular faces. - They are 10 – 15 meters in height. - Examples: Mushroom rocks in Wuling-jirapa, Ghana. PROCESSES OF WIND TRANSPORTATION IN DESERT REGIONS There are three processes of wind transportation. They are; 1.) SUSPENSION Is the process whereby wind lift fine particles of sand or silt to some few meters above the ground and carries from area to another. 2.) TRACTION Is a process whereby large fragments like boulders which cannot be lifted are rolled or dragged on the surface of the land from one area to another by wind. 3.) SALTATION Is a process whereby wind causes sand grains or coarse particles to move from one place to another in a series of hops or bounces. LANDFORMS PRODUCED BY WIND DEPOSITION IN DESERT AREAS Wind deposit the load it carries when it come into contact obstacles like rock, mound and vegetation.  64 Landforms or features produced by wind deposition include: 1.) BARCHAN OR SAND DUNES Is a crescent-shaped sand dune with two horn lying right angle to the direction of the wind. CHARACTERISTICS OF BARCHAN - They are found in desert like Sahara - They have crescent or half-moon shaped dunes - They have gentle and convex windward side - They have steep and concave leeward side. 2.) SEIF DUNES OR LONGITUDINAL DUNES Is a long, narrow and steep sided sand dune lying parallel to the prevailing wind. MODE OF FORMATION - Formed by wind eroding sand dunes - Formed by the central breaching of barchan - Formed by the emerging of several barchans. CHHARACTERISTICS OR DESCRIPTION SEIF DUNES  65 - They are features of sand depositions - They have long and narrow ridges - They have steep sides - They lie parallel to each other. 3.) LOESS Is the deposit of fine silt or dust particles transported by wind beyond desert boundaries. CHARACTERIISTICS OF LOESS - They are features of sand deposition - They consists of fertile and fine-grained soil. - They have porous and well-drained landscapes - They are found in desert regions WATER ACTION OR FLUVIAL EROSION IN DESERT AREAS Running water or river is an important agent of producing landforms in desert areas. SOURCES OF RUNNING WATER IN DESERT AREAS - Flash floods - Foreign Rivers - Melting snow from mountains to temperate highlands  66 - Past fluvial action PROCESSES OF WATER OR FLUVIAL EROSION IN DESERT AREAS 1.) HYDRAULIC ACTION Is the process whereby running water removes materials like sand, silt and gravels. This process also involves river surging into cracks of rocks along the valley floor of the river. 2.) ABRASION Is the process whereby the loose materials carried by the river are used to wear away the sides and beds of the valley floor. 3.) ATTRITION Is the process in which eroded materials being carried knock against each other and the bed – breaking up into smaller or rounded particles. 4.) SOLUTION Is the process whereby acidic water flows over soluble rocks like limestone. The acidic water causes the rock to dissolve and carried away as solution. LANDFORMS OF WATER OR RIVER EROSION IN DESERT AREAS  67 These are erosional features resulting from water or fluvial. 1.) WADI - Is a steep-sided valley with flat floor in desert areas. - It is usually dry except during torrential rainfall. - Formed by erosional action of torrential rainfall which produces flashflood. CHARACTERISTICS OF WADI - They are mostly found in arid and semi-arid regions. - They have steep sides and flat floor - They are features of erosional action of running water. - Their floor contain weathered materials or debris. - Examples Wadi al Masid in Libya and Wadi Abbad in Egypt 2.) CANYON - Is a deep, narrow trench with steep - sided valley{ V-shaped } - Canyon is formed in highlands or upland desert areas by the action of river erosion. The erosive power cut down the surface of the soft rock thereby widening the walls and floor of the valley. The V-shaped valley across the horizontal band of hard and soft rocks is called Canyon. CHARACTERISTICS OF CANYON - They are found in desert areas. - They are features of river erosion. - They have deep and narrow valleys.  68 - They are in high plateau and mountainous areas. - They have deep walls and marked by irregular gradient. - Examples: Fish river Canyon in Namibia ; Grand Canyon in Arizona-USA. 3.) PENEPLAIN - Is a low undulating land surface which is mostly a plain resulting from continued denudation. - Formed by the action of river erosion. River erodes the highland or uplands and divides them into individual plateaux or apartments with deep valleys of steep slopes. CHARACTERISTICS OF PENEPLAIN - They are found in upland desert areas. - They are features of river erosion. - They are extensive undulating plains. - Example: Peneplain of Mauritania 4.) PEDIMENT - Is a gentle sloping erosion surface or plain with sediments at the base of a receding mountain front. - Formed at base of desert uplands or mountains by action of river erosion, torrential rainfall or sheet floods. - When two or more Pediments join together{ coalsce } they formed PEDIPLAIN. CHARACTERISTICS OF PEDIMENTS - They are found in uplands desert areas.  69 - They are features of river erosion. - They have gently sloping surface. - They are slightly concave with the sloping angle ranging from 0.50 - 70 - Examples are found in the Sahara and Mojave Deserts. 5.) INSELBERGS OR BORNHADTS - They are isolated residual hills with rounded top and steep sides rising abruptly from the surrounding plains in desert regions. - Formed from semi-arid and arid regions by the action running water or wind erosion. CHARACTERISTICS OF INSELBERGS - They are found in semi-arid and arid areas. - They features of rainfall and running water. - Their height mat rise up to about 300 meters high. - Most inselbergs are made up of granite gneiss. - Examples: Shai and Krobo Hills in Ghana; and Brangberh Hills in Namib Desert. 6.) MESAS OR BUTTES - They are flat table-like and steep sided landmass with resistant horizontal top layer underlain by layers of soft rocks. - When the sizes of mesas are reduced to small isolated hills, they become Buttes.  70 - They are formed by the actions of extreme temperature, running water, rainfall and wind erosion on alternate bands of hard and soft rocks. CHARACTERISTICS OF MESAS AND BUTTES - They are found in semi-arid and arid areas. - They are products of running water, rainfall, or wind action. - They are flat-like land masses. - They are isolated flat-topped hills. - Examples are found in Sahara and Kalahari Deserts. DEPOSITIONAL LANDFORMS OF WATER OR RIVER ACTION IN DESERT AREAS. 1.) BAJADA - Is broad gentle sloping sediments bordering the foot of a mountain range by the coalescing of several alluvial fans. - They are formed by river deposition in desert. several rivers flow over linear mountain range picking sediments with other materials, as the river flow in areas of flat plains at the mountain base, it speed and energy reduce allowing deposition to take place. - Therefore, Bajada are two or more alluvial fans at the foot of the linear mountain range gradually coalesced or emerged together to form a broad gentle undulating slope with smooth surfaces. CHARACTERISTICS OF BAJADA - They are found in desert areas.  71 - They are features of river deposition. - They are fairly gentle undulating slope. - They have smooth surfaces - The slope is less than 70 2.) PLAYA OR SALINA - Is a temporay inland drainage basin with shallow lake of fluctuating volume encircled by a mud sheet. - It is simply a Temporary Salt Lake found in arid and semi-arid areas. CHARACTERISTICS OF PLAYA OR SALINA - They are found in desert areas. - They are features of desert river deposition. - They contain temporary salt lake. - They are usually found at the bottom of the basin or depression. - Examples: Playas in Algeria and Salinas of Lake Magadi of Kenya. - QUESTIONS FOR CLASS ASSESSMENT 1.) Temporary Salt Lake in arid and semi-arid regions are called a. Ventifacts c. Oasis b. Mesas d. Playa  72 2.) Which of the below landforms formed by Fluvial action is associated with Arizona, U.S.A. ? a. Canyon c. Peneplain b. Wadi d. bajada 3.) “They are crescentric or moon-shaped and occur individually or group”. The above description refers to a. Yardangs c. Barchans b. Seifs d. Pediment 4.) The plains formed when the slopes of mountains are worn back in desert area by mechanical weathering is called a. Pediplain c. Deflation plain b. Alluvial plain d. Outwash plain 5.) In an Oasis, water is derived from a. Bajada c. underground b. Rainfall d. playa  73 MASS WASTING DEFINITION OF MASS WASTING Is the movement ( sliding,, falling, creeping, or flowing ) of rock materials from one place to another under the influence of gravity. FACTORS AFFECTING MASS WASTING Gradient of the slope. Human activities. Nature and weight of materials. Presence of lubricating moisture. Presence of vegetation TYPES OF MASS WASTING A.) Soil creep Is the downward movement of soil materials down a gentle slope with the aid of water. Alternate wetting and drying ; heating and cooling are factors that promote soil creep. It is noticed when fence or tree bend towards the direct of soil movement. B.) SOLIFLUCTION OR SOIL FLOW Is when heavy rainfall turn the soil into semi-liquid state causing the soil to flow as Mud flow or Soil flow. C.) ROCKS FALL Is the most rapid mass wasting of all. This is the falling of large mass of rocks from a steep cliff. The repeated rock fall of broken rocks which collect at the base of the slope is called TALUS ( mound ).  74 D.) LANDSLIDE Is the movement of large rock debris over underlying weak rocks. Landslides are caused by Water down steep slope. River under-cut a steep slope. The pull of gravity. Earthquakes or volcanism Man activities. FORM OF LANDSLIDE Slumping Sliding SLUMPING Is very common where permeable rock layers overlies impermeable strata such ass clay.. - SLIDING Is the downward movement of materials flowing down steep slope. - EFFECTS OF MASS WASTING Leads to loss of farmlands. Results to displacement of settlements. Causes disruption of transportation network.. Leads to tilting of electric and telephone poles. Causing the damming of river. Leads to soil fertility AGENTS MODIFYING LANDFORMS Agents modifying landforms are rivers, glaciers, waves, and winds. RIVERS Rivers are running water or streams in the channel of banks.  75 Rivers is one of the important agents of denudation. Rivers are involved in erosion, transportation, and deposition of materials. TERMS ASSOCIATED WITH RIVERS Source of a river. Course of a river Mouth of a river River basin or catchment area. Watershed or water divide. River regime Confluence of a river Tributaries Distributaries River energy RIVER ENERGY - refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the river velocity. FACTORS AFFECTING THE VELOCITY OF A RIVER A.) The volume of water released B.) The slope of the river valley. C.) The shape of the river valley D.) The amount and size of materials. STAGES OF A RIVER A river has three main parts or stages. They are upper, middle and lower. THE UPPER OR YOUNG COURSE/STAGE Is the beginning or source of a river. Is found around highland/mountain areas. It has steep sides Dominant river flows swiftly down steep slopes  76 Dominant work is vertical erosion. FEATURES OF UPPER OR YOUNG COURSE OF A RIVER V-Shape valley Gorge River capture Rapid and cataracts Waterfalls THE MIDDLE OR MATURE COURSE/STAGE OF A RIVER Lateral erosion is dominant ( over vertical erosion ) Widening of river valley Wide V-Shape valley Presence of Bluff, River cliff, Meanders, Terraces. Increase in water volume. Increase in river load. Transportation is the river load. Little deposition. FEATURES OF MIDDLE OR MATURE COURSE/ STAGE OF A RIVER Wide V-Shape valley Meanders River cliff and Slip-off slopes Interlocking spur THE LOWER OR OLD COURSE/STAGE OF A RIVER Deposition is the main work Active lateral erosion Water volume increase Gradient of river valley lowers. Drastic reduction in river speed. FEATURES OF THE LOWER OR OLD COURSE/STAGE OF A RIVER  77 Flood plain Levees Ox-bow lake Braided river Delta RIVER EROSION Refers to the velocity of a river. The amount or quantity of materials a river erodes depends very much on the velocity. FACTORS AFFECTING THE VELOCITY OF A RIVER A.) The volume of water released B.) The slope of the river valley. C.) The shape of the river valley D.) The amount and size of materials. RIVER EROSION The load or materials carried by a river are the main agents of erosion. The erosive work of a river consists of four processes. They are: 1.) HYDRAULIC ACTION Is where the water enter into cracks and cavities causing them to enlarge. 2.) CORRASION Is the wearing of the sides and floor of the river valley by sand, pebbles, silts and boulders which are being transported. 3.) ATTRITION Is the wearing down of the loads as they collide with the valley and one another. Example: Large boulders are broken down into small pieces of pebbles. 4.) SOLUTION  78 Is the chemical action of water on materials. Example: Rock salt is dissolve this way. PROCESSES OF RIVER TRANSPORTATION A river transports it loads in four ways or processes. They are : 1.) SOLUTION Some materials dissolve in water and are carried to the lower course. 2.) SUSPENSION Is the carriage of larger particles suspended in the water as it flows. 3.) SALTATION Is the bouncing of materials either on the surface or at the floor of the river. 4.) TRACTION Is the dragging and rolling of the river load along the river bed. OX-BOW LAKE MODE OF FORMATION Formed in the lower of a river where there is pronounced meanders. As the waters in the river flow, there is erosion on the concave side and deposition on the convex bank. CHARACTERISTICS OF OX-BOW LAKE Feature of the lower course of a river. Occurs in marshy areas. Has horse-shoe shape Has a shallow convex bank. Has a deep concave bank. It is also called Bayous/Cut-offs. DELTA DELTA - is a fan-shaped alluvial plain formed as a result of deposition by river.  79 MODE OF FORMATION OF DELTA Formed from the deposition of sediments The absence of strong ocean current Presence of sediments at the estuary. FAVOURABLE CONDITION FOR THE FORMATION OF DELTA Active vertical and lateral erosion. Tideless coast or sheltered coast. Shallow sea adjoining the delta. No large lakes in the river course ( sediment removal ) No strong current at right angle to the river. CHARACTERISTICS OF RIVER DELTA Found at the lower course Occurs in swampy areas. Has seaward expansion of river flood plain Composed of alluvium Has distributaries. Has many shapes. TYPES OF DELTA There are three types of Delta. They are : 1.) ARCUATE DELTA Consists of both coarse and fine sediments. Has an inverted cone shape. It crosses many distributaries. 2.) BIRD FOOT DELTA Consists of fine materials called silts. Has several distributaries like bird foot. Extend into the sea. 3.) ESTUARINE DELTA Formed when there is partial submerged in coastal waters. Direct flow of water in the sea.  80 RIVER REJUVENATION A river is said to be rejuvenated when it is given a new lease of life or being young again. Example: an extra power of erosion. IMPORTANCE OF DELTA TO MAN Provides good agricultural land. It is good for fishing. Good for petroleum mining. ACTION OF GLACIERS IN TEMPERATE REGIONS Glacier action is an important agent of Erosion, Transportation and Deposition. It is common in mountainous and temperate regions. TERMS ASSOCIATED WITH GLACIERS 1.) ICE Refers to solid form of water resulting from freezing temperature persistently below 0 C. 0 2.) GLACIER Moving ice or very large sheet of ice. 3.) GLACIATION Refers to the wearing away of the earth surface by glacier. 4.) SNOW Refers to freezing water vapour which falls in the form of crystals. 5.) SNOW LINE Is the lower limit of perpetual snow cover on a mountain. 6.) SNOW FIELD Refers to the region or area permanently under snow cover.  81 ACTION OF GLACIER EROSION There are three ways by glacier carried out erosion. They are; 1.) SAPPING Is where rocks are broken up due to alternate freezing. The thawing of water at the bottom of cracks between a mass of ice and the sides and floor of a valley. 2.) PLUCKING Is the tearing away of blocks of rocks which have been frozen on the sides or bottom of a glacier. 3.) ABRASION Is the wearing away of rocks beneath a glacier by the scoring action. FEATURES OF GLACIER EROSION IN HIGHLAND AREAS 1.) STRIATION Are marks or stretches left on rocks over which glacier passes. 2.) CORRIES OR CIRQUE Is a deep and rounded hollow or depression with steep sides. It also results from plucking. After the ice has moved it forms Cirque lake ( Arm-chair-shape hollow ). 3.) ARETE Is the feature formed from when two Corries out back opposite sides of the same mountain. It is a Knife-edged ridge. 4.) PYRAMIDAL PEAK Is a pinnahttps://youtu.be/0_nlPbnrn1E cle shaped. Is a feature formed when three or more Corries cut back on the same mountain. 5.) BERGSCHRUND Is formed at or near the head of glacial. It is a deep and vertical crack. Small scale crack also develop where glacial negotiates a bend along it valleys. Such small cracks are called Crevasses. 6.) TROUGH OR U-SHAPED VALLEY  82 Is a wide , flat floor with very steep side. 7.) MORAINES Are made up of pieces of rocks that are shattered by frost action. FEATTURES OF GLACIAL EROSION IN LOWLAND A. ROCHE MOUTONNEE Are resistant residual rock structure. The surface is always rough. B. CRAIG AND TAIL Is a mass of hard rock which slopes on the upstream side and that protect the softer leeward slope from erosion. FEATURES OF GLACIAL DEPOSITION IN LOWLANDS 1.) BOULDER CLAY Is the ground moraine of the glacial. 2.) ERRATICS Are transported rock fragments. 3.) DRUMLINS Are swarms of oval, elongated whale-back hummocks. The shape of drumlin are better describe as “Basket of Egg”. 4.) ESKERS Are long, narrow and winding ridges of sand and gravel. 5.) TERMINAL MORAINES Are made up of boulders deposited at the edge of the ice sheet. 6.) OUTWASH PLAIN Is wide area of sand and gravel. ACTION OF WAVES IN COASTAL LAND Wave action is an important agent of erosion, transportation and deposition of materials confined to the coast of seas and oceans.  83 TERMS ASSOCIATED WITH WAVES 1.) WAVES Is the turbulent movement of water as a result of wind moving over the sea or ocean water. 2.) TIDE Is the alternate rise and fall of the surface water of the sea ( twice a day ). 3.) CURRENT Is the movement of the surface water of the ocean in a definite direction. 4.) COAST Is the meeting point between the land and the sea. 5.) SHORE Is the land portion lying between high water and low water. 6.) BEACH Refers to the materials deposited on the shore. It is usually sandy materials. 7.) SWASH Is the water that sucks back and retreats after wash. 8.) UNDERTOW Is the water which flows near the bottom away from the shore. MECHANISM OF WAVE EROSION There are four mechanisms of waves erosion. They are ; Corrosion, Attrition, Hydraulic action and Solvent action, See river erosion for explanation. FEATURES PRODUCED BY WAVE EROSION 1.) CAPE AND BAY  84 BAY is usually a space or land which contains water and could be used as harbor. Cape is a piece of land projecting into the sea it is associated with hard rock. A cape is times called Promontories or Headlands. 2.) CLIFFS Are steep rock faces adjoining the coast. 3.) COASTAL CAVE - Is formed by marine erosion. - Has a Arch-shaped - It may contain Bow-holes or Geo. 4.) ARCH Is the joining of two caves. 5.) STACK - Is the seaward portion of the promontory. - Is the collapsed arch of joined caves roof. 6.) STUMP Is the visible portion of a seriously eroded stack above sea level. 7.) GEO Is a narrow hole which results when a cliff is cut by a wave. 8.) GLOUP Is formed by wave erosion on a coastal cliff. Spray water in the cave enlarges a vertical joint in the roof resulting in loose blocks falling because of hydraulic action. FEATURES OF COASTAL DEPOSITION BEACHES Are made up of sand and gravels. Are formed when sand and gravels loosened from the land. They are depositional features SAND SPLITS Are ridges of sand and gravels formed by long shore drift across inlet.  85 MARINE DUNES OR DUNE BELTS Is the movement of large amount of coastal sand by onshore winds with large force. SAND BAR Formed by wave deposition in shallow sandy waters. Is a built-up of sand which is at times covered by water at high tide and exposed at low tide.  86 DESERT LANDFORMS DEFINITION OF DESERT Desert is a barren land that receives little precipitation with poor living condition to support plant and animal lives. ARID OR ARIDITY – Is the place having little or rain to support vegetation. Most desert or arid areas in the world lie between 150 and 300 north and south of the equator. The world largest cold desert is Antarctica. The world largest hot desert is Sahara The Dries or rainless desert in the world is Atacama The only continent with no desert is Europe. The desert plants without leaves are called Xerophytes. The desert plants with longest roots are called Phreatophytes. CAUSES OF ARIDITY These are factors that influence aridity in desert areas. Interior location or continentality. Cold ocean current Rain shadow effects or leeward location. CHARACTERISTICS OF DESERTS These are the appearances and description of deserts. They are: Low precipitation or rainfall High temperature Absence of vegetation cover High rate of evaporation High rate of physical or mechanical weathering Wind action is dominant Presence of cold current Internal drainage Presence of landforms.  87 TYPES OF DESERT LANDSCAPES 1.) SANDY OR ERG Is an undulating plain of desert with large amount of sand and sand dunes. It is produce by wind deposition. Example: Coastal sandy desert of Western Sahara. 2.) STONY OR REG Is a desert surface covered with gravels, stones, boulders and pebbles. It is produced by daily temperature change or exfoliation process of weathering. Example: Kalahari desert in Africa. Example Hamada el Homra in Libya 3.) ROCKY OR HAMADA Is a produced by erosional process of deflation and abrasion. Is a desert surface covered with large stretches of bare rocks. 4.) BADLAND OR MOUNTAIN DESERT This desert landscape develops in arid region of sudden rainstorm. Examples: Ahaggar in Algeria and Badlands in Dakota ( USA ). FUNCTIONS OR ROLES OF WIND IN THE DESERT AREAS. Wind perform three functions in desert areas. They are; erosion, transportation and deposition. ACTIONS OR PROCESSES OF WIND EROSION IN DESERT AREAS Wind erosion is carried out in the following ways. They are; 1.) DEFLATION  88 Is the lifting and blowing away of loose sand and pebbles by wind. The lowering of the land surface to form large depression called Deflation hollows. Examples: Qattara Salt Lake Depression in Egypt. 2.) ABRASION OR CORRASION Is the process of sand particles wearing away rock surfaces as they are blown by wind. Examples: Rock pedestal, Zeugens and Yardang. 3.) ATTRITION Is the process of wind borne particles colliding with each other resulting in the wearing away of each other. DIFFERENCES BETWEEN DEFLATION AND ABRASION Deflation is blowing away of loose rock waste whilst abrasion is the hauling of rocks against rock surfaces. Deflation usually results in lowering land surface whilst abrasion is most effective at the rock base. Deflation is associated with wind only whilst abrasion is associated with wind, water and wave. Deflation occur only in arid and semi-arid regions whilst abrasion occurs everywhere. WHY WIND EROSION IS MORE ACTIVE IN ARID AREAS THAN HUMID REGIONS Absence of vegetation cover Presence of friable and light soil Low rainfall LANDFORMS ORODUCED BY WIND EROSION IN DESERT REGIONS 1.) VENTIFACTS Is a faceted or flattered rock with smooth surface and sharp edges by wind-blown sand in desert area.  89 CHARACTERISTICS OF VENTIFACTS OR DREIKANTERS - They are found in hot desert regions. - They are features of wind sand-blast. - They may have one or more flat face or facet with sharp edges. - Examples: White desert near Farafar Oasis in Egypt 2.) ZEUGENS Is a tabular mass of rocks having alternate bands of hard rock lying over soft rock to form landscapes of ridges and furrows. MODE OF FORMATION Is formed when wind abrasion wears the mass rock into a ridge and furrow landscape. Mechanical weathering starts the formation by opening up joints of the surface of hard rocks. CHARACTERISTISTICS OF ZEUGENS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have horizontal bands of hard and soft rocks. - They are tabular masses of rocks separated by dee furrow. - They are 10 – 30 meters in height. - Examples are found in the Sahara, Atacama and Turkey. 3.) YARDANGS Are over hanging steep-sided ridges separated from each other by long narrow furrows. MODE OF FORMATION Are formed when the hard and soft rocks in vertical bands are aligned in the direction of the prevailing winds. Note that the soft rocks are wear away by wind abrasion causing corridor of long narrow softer rocks. The hard rocks are Yardangs.  90 CHARACTERISTICS OF YARDANGS - They are found in hot desert regions like the Sahara. - They are erosional features of wind abrasion. - They have vertical bands of hard and soft rocks. - They lie parallel to the prevailing winds - They are low overhanging ridges with steep sides. - Examples are found in Komombo in Egypt and Salah in Algeria. 4.) ROCK PEDESTAL Is a Mushroom shaped pillar of rock with irregular sides projecting above the surrounding desert plain. MODE OF FORMATION Are formed by wind abrasion on an alternate horizontal layers of hard and soft rocks. CHARACTERISTICS OF ROCK PEDESTAL - They are found in hot desert regions. - They are features of wind sand-blast. - They are mushroom-shaped rock. - They have steep and irregular faces. - They are 10 – 15 meters in height. - Examples: Mushroom rocks in Wuling-jirapa, Ghana. PROCESSES OF WIND TRANSPORTATION IN DESERT REGIONS There are three processes of wind transportation. They are; 1.) SUSPENSION Is the process whereby wind lift fine particles of sand or silt to some few meters above the ground and carries from area to another. 2.) TRACTION Is a process whereby large fragments like boulders which cannot be lifted are rolled or dragged on the surface of the land from one area to another by wind. 3.) SALTATION  91 Is a process whereby wind causes sand grains or coarse particles to move from one place to another in a series of hops or bounces. LANDFORMS PRODUCED BY WIND DEPOSITION IN DESERT AREAS Wind deposit the load it carries when it come into contact obstacles like rock, mound and vegetation. Landforms or features produced by wind deposition include: 1.) BARCHAN OR SAND DUNES Is a crescent-shaped sand dune with two horn lying right angle to the direction of the wind. CHARACTERISTICS OF BARCHAN - They are found in desert like Sahara - They have crescent or half-moon shaped dunes - They have gentle and convex windward side - They have steep and concave leeward side. 2.) SEIF DUNES OR LONGITUDINAL DUNES Is a long, narrow and steep sided sand dune lying parallel to the prevailing wind. MODE OF FORMATION - Formed by wind eroding sand dunes - Formed by the central breaching of barchan - Formed by the emerging of several barchans. CHHARACTERISTICS OR DESCRIPTION SEIF DUNES - They are features of sand depositions - They have long and narrow ridges - They have steep sides - They lie parallel to each other.  92 3.) LOESS Is the deposit of fine silt or dust particles transported by wind beyond desert boundaries. CHARACTERIISTICS OF LOESS - They are features of sand deposition - They consists of fertile and fine-grained soil. - They have porous and well-drained landscapes - They are found in desert regions WATER ACTION OR FLUVIAL EROSION IN DESERT AREAS Running water or river is an important agent of producing landforms in desert areas. SOURCES OF RUNNING WATER IN DESERT AREAS - Flash floods - Foreign Rivers - Melting snow from mountains to temperate highlands - Past fluvial action PROCESSES OF WATER OR FLUVIAL EROSION IN DESERT AREAS 1.) HYDRAULIC ACTION Is the process whereby running water removes materials like sand, silt and gravels. This process also involves river surging into cracks of rocks along the valley floor of the river. 2.) ABRASION Is the process whereby the loose materials carried by the river are used to wear away the sides and beds of the valley floor. 3.) ATTRITION Is the process in which eroded materials being carried knock against each other and the bed – breaking up into smaller or rounded particles. 4.) SOLUTION Is the process whereby acidic water flows over soluble rocks like limestone. The acidic water causes the rock to dissolve and carried away as solution.  93 LANDFORMS OF WATER OR RIVER EROSION IN DESERT AREAS These are erosional features resulting from water or fluvial. 1.) WADI - Is a steep-sided valley with flat floor in desert areas. - It is usually dry except during torrential rainfall. - Formed by erosional action of torrential rainfall which produces flashflood. CHARACTERISTICS OF WADI - They are mostly found in arid and semi-arid regions. - They have steep sides and flat floor - They are features of erosional action of running water. - Their floor contain weathered materials or debris. - Examples Wadi al Masid in Libya and Wadi Abbad in Egypt 2.) CANYON - Is a deep, narrow trench with steep - sided valley{ V-shaped } - Canyon is formed in highlands or upland desert areas by the action of river erosion. The erosive power cut down the surface of the soft rock thereby widening the walls and floor of the valley. The V-shaped valley across the horizontal band of hard and soft rocks is called Canyon. CHARACTERISTICS OF CANYON - They are found in desert areas. - They are features of river erosion. - They have deep and narrow valleys. - They are in high plateau and mountainous areas. - They have deep walls and marked by irregular gradient. - Examples: Fish river Canyon in Namibia ; Grand Canyon in Arizona-USA. 3.) PENEPLAIN  94 - Is a low undulating land surface which is mostly a plain resulting from continued denudation. - Formed by the action of river erosion. River erodes the highland or uplands and divides them into individual plateaux or apartments with deep valleys of steep slopes. CHARACTERISTICS OF PENEPLAIN - They are found in upland desert areas. - They are features of river erosion. - They are extensive undulating plains. - Example: Peneplain of Mauritania 4.) PEDIMENT - Is a gentle sloping erosion surface or plain with sediments at the base of a receding mountain front. - Formed at base of desert uplands or mountains by action of river erosion, torrential rainfall or sheet floods. - When two or more Pediments join together{ coalsce } they formed PEDIPLAIN. CHARACTERISTICS OF PEDIMENTS - They are found in uplands desert areas. - They are features of river erosion. - They have gently sloping surface. - They are0 slightly concave with the sloping angle ranging from 0.5 - 7 0 - Examples are found in the Sahara and Mojave Deserts. 5.) INSELBERGS OR BORNHADTS - They are isolated residual hills with rounded top and steep sides rising abruptly from the surrounding plains in desert regions. - Formed from semi-arid and arid regions by the action running water or wind erosion. CHARACTERISTICS OF INSELBERGS - They are found in semi-arid and arid areas. - They features of rainfall and running water. - Their height mat rise up to about 300 meters high. - Most inselbergs are made up of granite gneiss.  95 - Examples: Shai and Krobo Hills in Ghana; and Brangberh Hills in Namib Desert. 6.) MESAS OR BUTTES - They are flat table-like and steep sided landmass with resistant horizontal top layer underlain by layers of soft rocks. - When the sizes of mesas are reduced to small isolated hills, they become Buttes. - They are formed by the actions of extreme temperature, running water, rainfall and wind erosion on alternate bands of hard and soft rocks. CHARACTERISTICS OF MESAS AND BUTTES - They are found in semi-arid and arid areas. - They are products of running water, rainfall, or wind action. - They are flat-like land masses. - They are isolated flat-topped hills. - Examples are found in Sahara and Kalahari Deserts. DEPOSITIONAL LANDFORMS OF WATER OR RIVER ACTION IN DESERT AREAS. 1.) BAJADA - Is broad gentle sloping sediments bordering the foot of a mountain range by the coalescing of several alluvial fans. - They are formed by river deposition in desert. several rivers flow over linear mountain range picking sediments with other materials, as the river flow in areas of flat plains at the mountain base, it speed and energy reduce allowing deposition to take place. - Therefore, Bajada are two or more alluvial fans at the foot of the linear mountain range gradually coalesced or emerged together to form a broad gentle undulating slope with smooth surfaces. CHARACTERISTICS OF BAJADA - They are found in desert areas. - They are features of river deposition. - They are fairly gentle undulating slope.  96 - They have smooth surfaces - The slope is less than 70 2.) PLAYA OR SALINA - Is a temporay inland drainage basin with shallow lake of fluctuating volume encircled by a mud sheet. - It is simply a Temporary Salt Lake found in arid and semi-arid areas. CHARACTERISTICS OF PLAYA OR SALINA - They are found in desert areas. - They are features of desert river deposition. - They contain temporary salt lake. - They are usually found at the bottom of the basin or depression. - Examples: Playas in Algeria and Salinas of Lake Magadi of Kenya. - QUESTIONS FOR CLASS ASSESSMENT 1.) Temporary Salt Lake in arid and semi-arid regions are called a. Ventifacts c. Oasis b. Mesas d. Playa 2.) Which of the below landforms formed by Fluvial action is associated with Arizona, U.S.A. ? a. Canyon c. Peneplain b. Wadi d. bajada 3.) “They are crescentric or moon-shaped and occur individually or group”. The above description refers to a. Yardangs c. Barchans b. Seifs d. Pediment 4.) The plains formed when the slopes of mountains are worn back in desert area by mechanical weathering is called a. Pediplain c. Deflation plain b. Alluvial plain d. Outwash plain  97 5.) In an Oasis, water is derived from a. Bajada c. underground b. Rainfall d. playa