Explain how a sediment cell can be viewed as a system
• length of coastline + it assoc nearshore area in which movt of coarse
sediment (sand/shingle) is largely self-contained
• processes (erosion, transportation, deposition) within coastal margin is largely
contained within cells
• closed sys: no sediment transferred between cells
• England + Wales = 11 major/regional cells
- ↑ sub-cells of smaller scale
• boundaries determined by topography of coastline
- large features e.g. Llyn Peninsula, Wales
• reality, not fully closed due variation in wind/tidal currents
• coastal protection measures can disrupt cells - a ect sediment budget (inputs/outputs)
Explain the importance of geology, including lithology + structure on the coastal landscape
Lithology
• physical + chem components of rocks
• weak w. ↓ resistance to erosion, weathering, mass movt e.g. clay
- bonds between particles weak
• highly resistant e.g. basalt
- dense interlocking crystals
• vulnerable to carbonation as soluble in weak acids e.g. chalk/carboniferous limestone
• waves erode softer rocks faster than harder -> soft = bays hard = headlands
• Swanage Bay Area, Dorset
Structure
• properties of individual rocks e.g. joints, bedding + faulting & permeability
• primary permeability: air spaces (pores) separate mineral particles, absorb + store water e.g.
chalk
• secondary permeability: water seeps into vertical joints + horizontal bedding planes. joints easily
enlarged at points of weakness due solubility in weak acids e.g. carboniferous limestone
• in uence erosion -> cli s/arches
Explain how coastal sediment can be supplied from a variety of sources
Terrestrial
• majority
• rivers - 80% all coastal sediment
- deposited in river mouth/estuaries + reworked by waves, tides, ocean currents
• erosion of cli s
- in high energy enviros can supply up to 70% (typically much smaller)
• LSD
- transports from one stretch to another
O shore
• constructive waves bring from o shore locations + deposit on beaches
• wind blows from o shore exposed sandbars + coastal sand dunes
Human
• dumped by lorry on beach + bulldozed to spread (beach nourishment)
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, Explain the role of ocean currents in the development of coastal landforms + landscapes
• ow of water generated by Earth’s rotation, set in motion by movt of wind across water surface
• limited impact on coastal landscape processes
Downwelling
• warm ocean currents transfer heat from low lats towards poles
• particularly e ect W-facing coastal areas as driven by onshore winds
• strength of current = limited impact BUT transfer of heat can = signi cant as a ects sub-aerial
processes
Upwelling
• cold ocean currents transfer cold water from poles to Equator
• driven by o shore winds :. ↓ e ect on coastal landscapes
Rip Currents
• energy source, can = output of sediment -> erosional landforms
Explain the importance of the moon on the e ect of tides
• caused by grav pull of Sun + moon on oceans (moon = greatest in uence as nearer Earth)
• moon pulls water towards it = high tide
• semi-diurnal tides - 2 high + 2 low every 24hrs
Spring Tide
• Earth, sun + moon aligned, grav pull greatest
- higher high tide + lower low tide = high tidal range
Neap Tide
• sun + moon at 90°
- grav pull of sun partially cancels out grav pull of moon
- low high tide + high low tide = low tidal range
Examine the role of geomorphic processes in the formation of caves, arches, stacks and
stumps
Caves
• cracks/joints @ headland base (intertidal zone) exposed to hydraulic action :. widen
• further eroded by weathering (salt crystallisation/wet + dry)
• develop wave-cut notches —abrasion/hydraulic action—> widen/deepen cave
Arches
• wave refraction = distorts wave direction :. energy conc on headland side
• deepens cave. if 2 caves aligned, cut through = arch
• wave-cut notches widen base
Stacks
• vertical joints exposed to tall breakers + carbonation from above -> blowholes
• over time become unstable :. collapse = stack
• Old Harry, Dorset
Stumps
• further eroded at base = wave-cut notches. sub-aerial processes above
• eventually collapse = stump (broken material eroded by attrition)
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ff ff ff ff fl fi ff
• length of coastline + it assoc nearshore area in which movt of coarse
sediment (sand/shingle) is largely self-contained
• processes (erosion, transportation, deposition) within coastal margin is largely
contained within cells
• closed sys: no sediment transferred between cells
• England + Wales = 11 major/regional cells
- ↑ sub-cells of smaller scale
• boundaries determined by topography of coastline
- large features e.g. Llyn Peninsula, Wales
• reality, not fully closed due variation in wind/tidal currents
• coastal protection measures can disrupt cells - a ect sediment budget (inputs/outputs)
Explain the importance of geology, including lithology + structure on the coastal landscape
Lithology
• physical + chem components of rocks
• weak w. ↓ resistance to erosion, weathering, mass movt e.g. clay
- bonds between particles weak
• highly resistant e.g. basalt
- dense interlocking crystals
• vulnerable to carbonation as soluble in weak acids e.g. chalk/carboniferous limestone
• waves erode softer rocks faster than harder -> soft = bays hard = headlands
• Swanage Bay Area, Dorset
Structure
• properties of individual rocks e.g. joints, bedding + faulting & permeability
• primary permeability: air spaces (pores) separate mineral particles, absorb + store water e.g.
chalk
• secondary permeability: water seeps into vertical joints + horizontal bedding planes. joints easily
enlarged at points of weakness due solubility in weak acids e.g. carboniferous limestone
• in uence erosion -> cli s/arches
Explain how coastal sediment can be supplied from a variety of sources
Terrestrial
• majority
• rivers - 80% all coastal sediment
- deposited in river mouth/estuaries + reworked by waves, tides, ocean currents
• erosion of cli s
- in high energy enviros can supply up to 70% (typically much smaller)
• LSD
- transports from one stretch to another
O shore
• constructive waves bring from o shore locations + deposit on beaches
• wind blows from o shore exposed sandbars + coastal sand dunes
Human
• dumped by lorry on beach + bulldozed to spread (beach nourishment)
fl
ff ff ff ff ff ff
, Explain the role of ocean currents in the development of coastal landforms + landscapes
• ow of water generated by Earth’s rotation, set in motion by movt of wind across water surface
• limited impact on coastal landscape processes
Downwelling
• warm ocean currents transfer heat from low lats towards poles
• particularly e ect W-facing coastal areas as driven by onshore winds
• strength of current = limited impact BUT transfer of heat can = signi cant as a ects sub-aerial
processes
Upwelling
• cold ocean currents transfer cold water from poles to Equator
• driven by o shore winds :. ↓ e ect on coastal landscapes
Rip Currents
• energy source, can = output of sediment -> erosional landforms
Explain the importance of the moon on the e ect of tides
• caused by grav pull of Sun + moon on oceans (moon = greatest in uence as nearer Earth)
• moon pulls water towards it = high tide
• semi-diurnal tides - 2 high + 2 low every 24hrs
Spring Tide
• Earth, sun + moon aligned, grav pull greatest
- higher high tide + lower low tide = high tidal range
Neap Tide
• sun + moon at 90°
- grav pull of sun partially cancels out grav pull of moon
- low high tide + high low tide = low tidal range
Examine the role of geomorphic processes in the formation of caves, arches, stacks and
stumps
Caves
• cracks/joints @ headland base (intertidal zone) exposed to hydraulic action :. widen
• further eroded by weathering (salt crystallisation/wet + dry)
• develop wave-cut notches —abrasion/hydraulic action—> widen/deepen cave
Arches
• wave refraction = distorts wave direction :. energy conc on headland side
• deepens cave. if 2 caves aligned, cut through = arch
• wave-cut notches widen base
Stacks
• vertical joints exposed to tall breakers + carbonation from above -> blowholes
• over time become unstable :. collapse = stack
• Old Harry, Dorset
Stumps
• further eroded at base = wave-cut notches. sub-aerial processes above
• eventually collapse = stump (broken material eroded by attrition)
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