geography weathering, mass movement, rivers cards

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  • Created by: charlie
  • Created on: 03-11-13 16:58
denudation
general lowering of the earth's surface due to processes over the long term (erosion, weathering, mass movement)
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erosion
breakdown and transport of rocks (running water, waves, ice, wind)
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weathering
breakdown of rocks IN SITU (physical, chemical, biological)
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mass movement
process of soil, sand, regolith and rocks travelling downhill as a mass under the influence of gravity
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weathering depends on
climate, amount of vegetation, chemical make up of rock and rock structure (bedding planes + joints)
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physical weathering definition
physical break up of rocks owing to internal and external stresses caused by weathering agents
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physical weathering types
freeze thaw, pressure release, exfoliation
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freeze thaw facts
water expands 9.05 % exerting pressure 2115 kg/cm2 downwards
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chemical weathering definition
processes which lead to decomposition/breakdown of solid rocks by chemical reactions
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chemical weathering types
carbonation, oxidation, hydrolysis
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biological weathering definition
group of processes produced by actions of plants + animals
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biological weathering types
root action, excavation, acidification
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types of mass movement flows
mudflows (v. fast + wet), earthflows
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types of mass movement slides
landslides, rockslides (dry and faster)
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mass movement slides definition
movement of any mass of material, rock or regolith along a slip plane (including rotational slumps + slides)
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landslides C.S
aberfan 21/12/1966 - spoil heap no. 7 built above spring removing clay -147 died
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mass movement heave definition
downslope movement caused by expansion + contraction
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types of mass movement heaves
soil creep (turf only bond to top soil layer), solifluction (soil creep plus- moist ground expanding when frozen)
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mass movement falls definition
movement off steepest bare rock slopes (40+ degrees)
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drainage basin
area drained by one river and its tributaries. water + sediment are moved downslope by river from highland to sea/lake
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inputs of drainage basin
precipitation
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robert E horton theory
overland flow occurs when input > infiltration
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stores of drainage basin
interception, surface storage, soil water storage, groundwater storage
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flows of drainage basin
throughfall, stemflow, leafdrip, infiltration, percolation, overland flow, through flow, base flow
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outputs drainage basin
river run off, evaporation, transpiration (evapo-transpiration)
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water shed
boudary between two basins
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source
river originates
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mouth
river enters sea/lake
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distributary
river splits to smaller streams
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tributary
smaller streams join river
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confluence
point where tributary + river meet
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ephemeral channel
grass bent over + occupied during floods
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blue line system
rivers on a map
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C.S Boscastle flood
months rain (200mm) in 1hr, impermeable shale clay + circular basin, brown willy effect caused precip over mountains,
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C.S boscastle defences post flood
widened bridge, landscaping, dredging, storm drains (culverts), renovated buildings
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downstream changes in a river - BRADSHAW theory
river system is organised/ordered transport system for water + debris in general rivers are at a close to equilibrium
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upper course erosion landforms
interlocking spurs, potholes, rapids + waterfalls
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bradshaws model downstream increases
discharge, load quantity, occupied channel width, channel depth, average velocity
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bradshaws model downstream decreases
load particle size, channel bed roughness, slope angle (gradient)
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maximum velcoity
thalweg
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average velocity
40 % from bottom - measure over 10m then times by 0.8
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hydraulic radius
C.S.A / wetted perimeter
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discharge (cumecs)
C.S.A (m2) x VELOCITY (m/s)
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bedload
particles moves or rolls + always in contact with bed
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saltation
happens by BERNOULLI EFFECT - other particles pushed into motion due to impact of initial particle
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suspension load
bedload + saltation load suspended as velocity inc. in lower course
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Other cards in this set

Card 2

Front

breakdown and transport of rocks (running water, waves, ice, wind)

Back

erosion

Card 3

Front

breakdown of rocks IN SITU (physical, chemical, biological)

Back

Preview of the back of card 3

Card 4

Front

process of soil, sand, regolith and rocks travelling downhill as a mass under the influence of gravity

Back

Preview of the back of card 4

Card 5

Front

climate, amount of vegetation, chemical make up of rock and rock structure (bedding planes + joints)

Back

Preview of the back of card 5
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