case study-high energy coastal environment Flashcards
what processes are in action at durdle door
WCN- abrasion, hydraulic action, solution (limestone)
ISTHMUS- hydraulic action, abrasion, biological weathering, oxidation, mass movement (rockfall)
TOP OF ARCH- nesting birds, biological weathering, gravity
what will happen to durdle door in the future
-left with chalk cliffs
-isthmus will retreat and be taken away
-arch will collapse and form a stack then a stump
-st oswalds bay will become a joint bay
what processes are happening at stair hole
BLOW HOLE- hydraulic action, abrasion
ARCH- biological weathering, chemical weathering, gravity
BEACH- attrition of material on beach leads to slumping
CAVE- hydraulic action, attrition and abrasion
what will happen in the future to stair hole
-cove will enlarge and join with another cove (sea will escavate it)
-vice will enlarge to sides
-cave will erode through to create an arch
-arch will collapse and portland limestone will erode away
what processes are occurring at lulworth
EROSION- hydraulic action, abrasion, solution
WEATHERING- oxidation (s+c), biological weathering, chemical weathering, freeze thaw in chalk, wetting and drying in S+C
MASS MOVEMENT- rockfalls in limestone and slumping in sands and clays
what will happen in the future to lulworth
-will erode to side but not back due to harder purbeck chalks
-more slumping
-portland stone becomes detached from mainland to create island
-will become a jointed cove with stair hole
key landforms at dorset coast
-man o war rocks
-durdle door
-cliffs at lulworth
-cusp of sand behind man o war rocks
-stair hole
-slumped and vertical cliffs
sediment inputs at dorset
-cliffs (major)
-longshore (minor)
-offshore (minor)
-river sediment(very minor)
sediment outputs at dorset
offshore and longshore
sediment stores at dorset
-beaches- shingle and sand
-cliffs -cliff foot and debris
why is dorset coast considered a high energy coastline
-long fetch across atlantic
-exposed to SW prevailing winds
-macrotidal environment
-dominated by erosion
-destructive waves
what did the coastline look like a millennia ago
straighter coast and more limestone
how did lulworth originally form
-a river found a fault in the chalk and limestone after the last ice age and the sea carved the core out
-Portland limestone forms a barrier entrance to the cove as it’s more resistant- the sea hits here first and waves are refracted
features of the concordant coast
-bays more elongated and ovoid in shape
-headlands do not stick out as much
-rock strata parallel to sea
-one rock type facing the sea therefor rock erodes at same rate
features of the discordant coast
-bays deep
-headlands stick out
-different rates of erosion as alternating hard and soft rock
