Coastal Flashcards
(15 cards)
Explain Abrasion
Sea picks up rocks, throws at cliff, wearing away surface like sandpaper
Explain Hydraulic action
Water from waves pushed into cracks of cliff face, pressure builds till rock breaks apart
Explain Attrition
Rocks and pebbles carried by waves smash into each other, gradually becoming smaller rounder and smoother
Give answer for Headlands and bays
- Differential erosion
- Alternating bands of different rock types when sandstone and clay meet at right angle
- 2 x erosion processes
-Softer rock erode back into bay - Harder rock jut out as headlands
Named example of Headland and bay
Swanage Bay
Explain differential erosion
Hard rock erodes slower than soft rock
Give answer for Caves, arches, stacks or stumps
- Weakness in headland eroded by 2x erosion processes
- Explain those processes
- Overtime widens to become sea cave
- Cave erodes further back into headland, eventually breaking through becoming arch
- Arch eroded at low and high tide, widens arch, roof is unsupported
- Roof collapses leaving stack
Named example of Caves, Arches, Stacks and Stumps
Old Harry
Give wave cut platform answer (hint: think boxing)
Weaknesses in rock undercut by wave erosion
This forms wave cut notch
Notch enlarged, eventually overhanging rock collapse
This repeats, cliff retreats, exposing sloping rock surface called wave cut platform
Explain Longshore drift
1) Waves approach beach at 45 degree angle (swash)
2) Material dragged back down at 90 degree angle due to gravity (backwash)
3) Material moves in direction of prevailing wind (UK = SW)
Define a Spit
Beach that grows out to sea instead of following along the coast
Why do spits form behind headlands?
Calm water
Shallower water
Sea currents weak when protected from wind
Define a Bar
Beach that grows across mouth of a bay cutting off water from sea
Define a Tombolo
Spit that joins to an island
