Coasts Revision - Physical Processes

- The characteristics of waves.

- How erosion and weathering shape the coastline.

- How rock type and structure influences coastal landforms.

- How to describe the landforms associated with ‘hard’ and ‘soft’ coastlines.

- How waves move beach sediment.

- How the deposition of beach sediments creates coastal landforms.

Coast - where the land meets the sea

Waves - the wind pushing the water

Crest - top of a wave

Trough - bottom of a wave

Marine Erosion - wearing away of rocks by the action of the sea

Weathering - breaking down of rocks by weather, plants or chemical action

Prevailing Wind - the dominant wind in an area

Swash - movement of water travelling up the beach

Backwash - movement of water travelling away from the beach

Fetch - distance the waves have travelled 

Constructive wave - a wave with a stronger swash 

Destructive wave - a wave with a stronger backwash

- Headlands and Bays

- Caves

- Arches

- Stacks 

- Stumps

- Wave cut platfoms 

Slides - material shifts in a straight line 

Slumps - material shifts with rotation

Rockfalls - material shifts vertically

- Headlands are usually made of resistant rocks, but they have weaknesses like cracks

- Waves crash into the headlands and enlarge the cracks - by hydraulic action and abrasion 

- This causes a cave to form

- Continued abrasion deepens the cave until it breaks through and forms an arch

- Erosion continues to wear away the rock which supports the arch until it collapses

- This forms a stack - an isolated rock that's seperate from the headland, like Old Harry

- The stack is worn down to form a stump, like Old Harry's Wife

- Shallow and widely spaced apart

- Small in height and low in energy

- Movement up the beach (swash) is strong

- Carry material up the beach creating depositional landforms

- Steep, close together and quick breaking

- Large in height and high energy

- Strong backwash

- Remove (erode) material from the beach creating erosional landforms

Corrasion/abrasion - where the water gradually wears away the surface of the rock stores

Attrition - rocks are smashed together and made into smaller pieces by waves and their edges are rounded off

Corrosion - the weak carbonic acid in the sea water dissolves rock like chalk and limestone

Hydraulic action - the force of the water against rocks makes cracks appear and eventually bits of rock break off

Landforms caused by Longshore Drift -

Spit - forms at sharp bends when sand and shingle are carried past the bend and deposited, strong wind then forms the curve

Bar - a spit which joins two headlands together and cuts off the bay, a lagoon then forms behind the bar

Tombolo - a bar which connects the shore to an island eg Chesil Beach

Erosion/Weathering - Transportation - Deposition

The coastal system acts like a conveyer belt. Material is worn away from some places, then moved by waves and deposited in other places.  

Headland and Bay - The Foreland and Swanage Bay in Dorset

Arch - Durdle Dorr

Stack and Stump - Old Harry and his Wife

Spit - Spurn Head or Hurst Castle 

Tombolo - Chesil Beach in Dorset which joins to the Isle of Portland

Lagoon - The Fleet lagoon (behind Chesil Beach)