CASE STUDY - SKOMER - high energy coastal environment Flashcards
(15 cards)
how do CURRENTS affect Skomer
a01
- North Atlantic drift brings warm, saline water with high energy
- increases erosion where waves attack faults
- reinforces marine erosion but doesnt differ spatially across island
a02
-large scale - doesnt vary much across skomer
- slightly contributes to weathering especially at Bull Hole and Jack Sound
how does WIND affect Skomer
a01
- SW prevailing winds –> high fetch and high energy waves on west side
- waves approach at an angle –> shapes the coatsal morphology
a02
- steep eroded SW coast
- depositional NE coast
- important at regional scale
how do WAVES affect Skomer
a01
- waves have very large fetch - from Carribean
- high energy destructive waves dominate
- wave refraction focuses energy on headlands - damages faults
a02
- main cause of cliff retreat and erosional landform development
- responsible for inlets (the wick) and blowholes (bull hole)
how do TIDES affect Skomer
a01
- macrotidal range of 7m (jack sound) - strong vertical erosion
- tidal surges concentrate ocean energy at cliff bases
- this affects the sediment deposition on the NE side
a02
- Jack Sound tidal flow >6 knots - very high - enhances sediment transport and erosion
- increases erosion on south coastline
- more localised importance when funnelling occurs (the neck)
how does LITHOLOGY affect Skomer
a01
- Resistant igneous rocks dominate (e.g., basalt, rhyolite, mugearite)
- Some interbedded sedimentary rock (e.g., sandstone, conglomerate).
- determines erosion rate, cliff stability and mass movement type
a02
- the neck (south side is sandstone) = less steep, more weathered, more slumping.
how does STRUCTURE affect Skomer
a01
- faults and joints create zones of weaknesses –> allows ocean erosion to penetrate inland
- creates geos and blowholes (bull hole) and inlets (the wick)
a02
- local factor
- faults directly responsible for landform development
- The Wick: aligned to a major fault.
- The Neck: fractured and narrowing due to active erosion.
inter-relationships between landforms - THE WICK
- fault-aligned steep inlet
- formed by wave refraction and vertical cliff erosion
- one side is steep (basaltic lithology), the other side is gently sloping (sedimentary)
- active mass movement: rockfall (steep side) vs slump/creep (shallow side)
inter-relationships between landforms - BULL HOLE
- geo on NW headland
- formed by fault in basalt/ mugearite rock
- wave compresses air/water into cracks –> erosion of tunnel –> roof collapse = blowhole
inter-relationships between landforms - THE NECK
- heavily faulted
- south: made of conglomerate sandstone
- north: depositional sediment
- strong wave action narrowed the land bridge, creating potential for future island split
inter-relationships between landforms - SOUTH HAVEN
- formed in less resistant rock or fault zones –> embayment and sediment accumulation
- north haven - protected from prevailing winds –> allows sediment to build up
inter-relationships between landforms - OTHER
Wave-cut platforms, sea caves, and marine notches are found around high-energy zones like Jack Sound and The Wick.
how does the landscape change OVER MILLENNIA (geological change)
- formed during Ordovician period by volcanic eruptions –> complex lithology
- over time: tectonic uplift and erosion exposed faults + joints, marine processes exploited these –> geogs, stacks, arches etc
- structural weaknesses become wider specially in places like bull hole
how does the landscape change - SEASONAL and DECADAL
- winter: higher wave energy –> higher erosion (eg undercutting cliff bases)
- summer: calmer waves allow minor sediment deposition (eg North Haven)
- short term collapses at fault zones (eg steep cliff face at Wick)
- slumping in sedimentary zones eg north of Neck
how does the landscape change - LONG TERM
- resistant rock (e.g. rhyolite, basalt) retreats slowly → forms headlands and stumps.
- interbedded weaker rocks and faults erode faster –> forming inlets and bays
- over centuries: further undercutting, collapse and isolation of headlands like The Neck
human factors and management response
HUMAN
- policy unit 1.3 - no active intervention until 2105 –> remote, protected
ECOLOGICAL
* National Nature Reserve (NNR), SSSI, SAC, Marine Nature Reserve
* Home to puffins, razorbills, Manx shearwaters → environmental protection prioritised.
- Conservation > coastal defence → allows natural processes to operate freely.
