4 Classic River Profile River Profile Source Mouth + Delta Upper Course Middle CourseLower CourseSteep groundModerate groundGentle groundFast flowModerate flowGentle flowErosionTransportationDepositionV-shaped valleyWaterfallSmall meanderSmall floodplainLarge meanderLarge floodplainOxbow lake
5 River Processes - Transportation Now Watch The Flash PresentationOn River Transportation
6 River Processes - Transportation DescriptionSaltationForce of water drags or rolls rocks along river bed.TractionDissolved material is carried along in the water.SuspensionPebbles are picked up and bounced along the river bed by flowing water.SolutionVery light clays are held up in the water as it flows.
7 River Processes - Erosion Abrasion/CorrasionHydraulic ActionCorrosionAttritionForce of water hitting off river banks causes them to wear down.Stones carried by river hit into river bed and bank, eroding & scraping them.Stones collide into each other knocking edges off – get smaller and rounder.Rocks dissolve in water e.g. limestone
8 Landforms Of The Upper Course V-shaped ValleysWaterfalls
10 1 As the river flows it erodes downwards initially, due to the great energy it has. This happens mainly because of the process of corrasion (explain in detail for in exam!)
11 2 The river therefore forms a deep and steep sided channel 2 The river therefore forms a deep and steep sided channel. Over time freeze thaw (again explain) weathering acts upon the riverbank. This loosens the rock and soil.
12 3 As the rock & soil from the river bank breaks up, it is transported to the river by to gravity and the wash effect of rain on the soil.
13 4 The eroded material that falls into the river is then transported downstream by the river and isdeposited on its bed or on a river beach.
14 River erodes downwards due to fast flowing water carrying stones. 13241234River erodes downwards due to fast flowing water carrying stones.A deep/steep sided channel forms & weathering loosens soil on the banksRock & soil from river bank breaks up, falls into river due to gravity & rainEroded material transported downstream and deposited on river bed.
19 gorge ~ soft ~ abrasion ~ collapses ~ cliff ~ deeper ~ plunge ~ hard Waterfallgorge ~ soft ~ abrasion ~ collapses ~ cliff ~ deeper ~ plunge ~ hardA waterfall is formed when a river flows over a layer of ______ rock, which is lying over a layer of soft rock. The _____ rock erodes more quickly. The hard rock sticks out forming a _____ in the river, which is a waterfall. The soft rock at the bottom of the waterfall/cliff is then eroded further to form a ____________ pool. This pool becomes bigger and ____________ as water swirls broken rock around. The hard rock is left unsupported and so eventually ______________. Over a long period of time the waterfall retreats backwards forming a narrow and steep sided valley called a _______. You will gain marks for describing either how the erosion occurs e.g. Hydraulic Action & __________.hardsoftcliffplungedeepercollapsesgorgeabrasion
20 Landforms Of The Middle & Lower Course Oxbow LakeMeanderFloodplain
22 MeandersInner Bend Outer BendSlow Flow Fast FlowLow Energy High EnergySmall Rocks Large RocksDeposition ErosionShallow Water Deep WaterRiver Beach River Cliff
23 Meander - River bend Bank will collapse Fastest current slowest currentSmallrivercliff( river beach )Deposition ofSand and shingleOuter bankIs undercutDeepest partof the river
24 Meanders - Sequence Exercise Use your cross section diagram and the words in the same order as below to write 2 paragraphs explaining how meanders form.Paragraph 1Outer bend ~ fast flow ~ high energy ~ large rocks ~ erosion ~ deep water ~river cliff.Paragraph 2Inner bend ~ slow flow ~ low energy ~ small rocks ~ deposition ~ shallow water~ river beach
25 Formation of a MeanderAlluvium river cliffs greatest speed depositionerosion loss of energy meandersThe course of a river usually has many bends in it. These arecalled___________. The _____________of water is on theoutside of the bend where _________takes place and thechannel is worn away to make___________The water flowsmore slowly round the inside of the bend. This causes__________________ and _________________ when the riveroverflows its banks it deposits material called ______________ on the valley floor.meandersgreatest speederosionriver cliffsloss of energydepositionalluvium
31 Oxbow LakesOuter BendAn oxbow lake starts to form when large meanders develop close together (A). As their outer bends erode more, there is only a small piece of land remaining between them, called a neck (B).Large MeandersNeck
32 Straighter ChannelEventually the river erodes through the neck of the meander and makes a new straighter river channel (C). The river now flows down this channel and deposits material blocking up the old channel.DepositionOld Channel
33 This leaves an oxbow lake in the old river channel and without a supply of water the lake can dry up (D). The lake may reform when there is heavy rain or flooding.Oxbow Lake
36 FloodplainAFEBCDA =B =C =D =E =F =Bluff LineLayers Of AlluviumRiver Bed Level Rises With Increased DepositionSmall Particles Deposited Away From RiverLarger Particles Deposited Close To RiverLevee
37 FloodplainA floodplain is a flat area of land either side of a river, which floods regularly. The widest examples are found in the middle and lower course.The river valley gets wider as meanders continue to grow, eroding back the sides of the valley.The flat valley that forms is called a floodplain and develops as alluvium (mud/silt) sediment is deposited after a flood.The smallest particles are found at the edge of the floodplain and the largest particles nearest to the river. The largest particles by the river bank form a mini ridge called a levee, which runs parallel with the river.