Coast Outputs (Erosional Landforms) Flashcards
Define bays
Soft rock eroded quickly forming a large coastal indentation
Define headlands
Hard rock eroded less and sticks out into the sea
How are headland and bays formed?
Bands of alternating hard & soft rocks at right angles
Outline how
Outline how coves are formed
Concordant coastlines - resistant rock can be broken through and worn away -> waves erode less resistant rocks behind until it meets resistant rock
Outline an example of a cove
Lulworth Cove, Dorset, UK
Portland stone broken through allowing weaker clays & sandstones to be eroded until resistant chalk stopped
Outline how wave-cut platforms are formed
High steep waves break at the foot of a cliff - power concentrated over a small area -> cliff undercut (forms a wave cut notch)
Continual = stress -> collapse.
Cliff retreats leaving a wave cut platform
What type of features are caves, blowholes, arches, stacks and stumps?
Temporary features - caused by retreat and erosion of cliffs
Outline the formation of caves
Hydraulic action & abrasion attack weak areas in rock. This loosens blocks along joints below the HWM - create hollows (caves)
Outline the formation of blowholes
Roof of a cave is weakened along major joints by hydraulic pressure - collapses into vertical shaft called a blowhole
Outline how a geo is formed
If the entire roof of a blowhole cave collapses - a geo forms
Outline the formation of an arch
A cave extends backwards to meet another cave creating a hole all the way through the headland
Outline the formation of a stack
An arch forms and the the cliff retreats further leading to the collapse of an isolated portion (stack)
Outline the formation of a stump
The wave cut notch at the base of the stack is eroded further - collapsing the stack and forming a stump
Outline how lithology & structure influences cliff profiles
Resistant rocks (limestone) - erode slowly and are stable at steep angles
Weak rocks (clay) - erodes quickly & often forms low-angle profiles
Outline horizontally bedded rocks influences cliff profiles
Horizontally bedded rocks form vertical cliffs
Cliff retreat by wave action parallel to themselves staying steep
How do landward-dipping strata influence cliff profiles
Forms steep cliffs - eroded and weathered rock particles aren’t easily dislodged from cliff face
How do seaward-dipping strata influence cliff profiles?
Develop profiles which mirror the angle of dip of the bedding planes.
