headland/bay/cliffs/wave-cut platforms/ caves Flashcards
characteristics of Durlston Head? rock? cliff face? waves? cave?
6
- durlston Head is a cliff and headland
- Portland limestone
- near vertical cliff face
- destructive waves (high-energy) affected headland
- cave forming on either side of cliff
- stack and stumps form
characteristics of a bay? what is a bay? name of bay in Dorset? soft or hard rock? waves? sand accumulation?
- bay = resent-shaped indentation of the coastline, found between two headlands
- has a beach (shingle or sand)
- bay is made from soft rock (sand/clay)
- low energy constructive waves
- sand accumulates in the down-drift (NORTH section) due to LSD
how are headlands formed and developed?
coastline type?
hard and soft rock?
low/high -energy environments?
deposition?
erosion?
- from on a discordant coastline where soft rock (e.g clay or sand) is eroded faster than hard rock (grant/limestone). result in the formation of headlands and bays.
- once headland and bay has formed: sheltered bay (headlands shelter) = low-energy environment, deposition occurs, beach is formed
- exposed headland become targets of erosion
explain the process of wave refraction
3
1) headlands become targets for erosion because of high-energy waves
2) waves refract at headland
3) deposition occurs at bay because of low-energy constructive waves that have spread out
characteristics of a wave cut platform?
platform
(4)
- platform = 3 degrees slope (gentle)
- platform covered at low tide
- barnacles clinging on rock
- shingle collects at sea ward side of platform (steep)
characteristics of Burton Bradstock cliffs? height? rock bedding cliff face base rock fall (7)
- height = 45 m
- hard rock (sandstone)
- horizontal bedding
- layers of rock jutting out
- near-vertical cliff face
- wave-cut notch at base
- rocks fallen at base
formation of wave-cut platforms? weathering erosion base notch collapses retreats (6)
1) free-thaw weathering weakens rock at cliff
2) marine erosion is concentrated at base of cliff (hydraulic action and abrasion)
3) rocks break away + collect a base
4) wave-cut notch formed
5) overhanging cliff is unsupported and collapses resulting in wave-cut platform
6) cliff retreats from the continuous removal of rock at wave cut notch
formation of caves, stacks, stumps (7) crack weathering notch cave arch unstable stack stump
1) large crack at cliff where hydraulic action is concentrated here
2) crack grows into a notch, destructive waves erode crack further
3) crack turns into a cave
4) sea breaks through cave to form an arch
5) freeze -thaw weathering weakens top of arch, making it unstable and falls
6) leaves a stack
7) stack will topple into sea to form a stump
characteristics of a cave? (2)
entrance
get in
- few metres tall at entrance
- narrower as you get in
how does a blow hole form?
- pressure from waves pushes water up blow hole so it emerges on the cliff above
characteristics of an arch? (4) top base gap headland
- unsupported top
- wave-cut notches at base
- water goes though gap
- arch = extension of headland
characteristics of stumps? (2)
- seen at low tide
- bases of collapsed stacks
