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CfE H Geography - Lithosphere - Coasts Revision
Transcript of CfE H Geography - Lithosphere - Coasts Revision
CLIFF / WAVE-CUT PLATFORM
HEADLANDS & BAYS
A discordant coastline is when there are altering layers of hard and soft rock in contact with the sea; this allows the soft rock to be eroded faster forming a headland. [
] Headlands cause waves to refract around them eroding the headlands from the side.
CAVES, STACKS & STUMPS
Lines of weakness or faults in the headland can be eroded to form small caves. [
]. Blowholes can be formed when air trapped in the cave explodes upwards further eroding a line of weakness. Further erosion can take place to allow the cave to be eroded right through to the other side of the headland forming an arch. A stack is formed when the roof of the arch is no longer able to support itself and collapses.
The next part of the Prezi contains a good video for revision - it does last just over 18 minutes so make sure you have enough time to watch it!
Remember to use your can-do checklist to help you prioitise your revision
Questions in the exam will most likely be in the following format:
CONDITIONS AND PROCESSES
involved in the formation of [one of the features]
You must mention conditions and if possible all processes (4 for Erosion, Longshore Drift for Deposition)
The longer the wind has been blowing combined with the distance the wind has been blown across the sea/ocean (FETCH) the more energy the waves will have, and therefore, more erosive power
Areas that have well-jointed rocks are more easily attacked by the process of HYDRAULIC ACTION.
Hydraulic action is when waves force air under high pressure into cracks in the coastline, over time forcing them apart.
CORRASION / ABRASION
Abrasion is when material carried by the waves scrape against the headland wearing it away
CORROSION / SOLUTION
Chemicals (weak acid) and salt in seawater slowly dissolve rock minerals on the coastline.
Attrition is when beach material is knocked together reducing its size and making it smoother and rounded. This adds material to support abrasion.
On-shore winds make waves approach at an angle (swash), but they go back down (backwash) at right angles to the beach. Resulting in material gradually moving along the coastline
COASTAL EROSION FEATURES
BARS / TOMBOLOS
A 'bar' is formed if deposition keeps going right across a bay, and joins up with a beach on the other side.
Shallow, stagnant water, trapped behind the bar, is called a 'lagoon'.
A 'tombolo' will form when a spit grows out into open water and reaches an island. The island is then joined to the mainland by the tombolo.
COASTAL DEPOSITION FEATURES
Cliffs form where there is harder more resistant rock such as granite or chalk. Wave energy is at its greatest when a high, steep wave breaks at the foot of a cliff—over time a wave cut notch is formed. [
]. Continued erosion causes the notch to become larger over time—undercutting the cliff causes the cliff above to become unsupported and eventually collapses. The cliff retreats and leaves behind a gently sloping wave cut platform which can be deeply dissected by tidal movements and by solution.
Long shore drift is the lateral movement of material along a beach when waves, driven by the prevailing wind, push material up the beach; known as the swash. The returning backwash is dragged back by gravity down the beach at right angles. Spits are low ridges of beach material which form where the coastline changes direction and where there is shallow water. Often a secondary wind (one less prevalent) can cause the spit to form a hooked shape called a recurve or hooked spit. In the sheltered area between the spit and land a salt marsh may form.