Coasts

coasts

contact zone between land and sea

Why coastlines are so important in the uk

Home to 30 million people

employment and food in fishing industry

tourists spend 8 billion every year

imports and exports come by ships

waves

generated by wind blowing over the sea

Size of waves

stronger the wind, greater the friction on the surface of the sea, bigger wave

Swash

when a wave breaks, water rushes up the beach, approaches at an angle

Backwash

water runs back down the beach at a 90 angle; because of gravity.

Factors affecting size of wave

strength of wind, length of time the wind has been blowing, fetch/distance the wave has travelled

What happens as waves reach shallower water

Circular orbit in orbit, water becomes more elliptical in movement, friction slows base of wave, top of wave moves faster & increasing elliptical movement, wave begins to breaks. swash and backwash.

How are waves formed?

Wind blows over sea surface, creates drag/friction on water, creating a swell. energy of wind causes water particles to rotate as the wind passes over.

What do waves do?

erode the cliffs, transport eroded material, deposit material

Destructive waves

Little swash, strong backwash. Wave breaks downwards with great force. Long fetch, high energy, short wave length, high waves

Constructive waves

strong swash deposits material. weaker winds, short fetch, low waves, low energy, weak backwash

Weathering

disintegration or decay of rocks in their original location. results in angular fragments of rocks

Physical weathering

freeze-thaw weathering causes pressure in cracks and breaks away.

Chemical weathering

weak acids in rainwater react with rock types and cause them to break away

Biological weathering

seeds falling into cracks and grow, roots expand and break away the cliff

Types of mass movement

slide, flow, slump, fall

Slide mass movement

top layer of rock is saturated by rain, gravity makes it break off and slide

flow mass movement

fine loose material becomes saturated with water and flows down slope

slump mass movement

rain saturates cliff top, waves attack cliff at the base & undercuts them, rock slumps into sea. happens in soft rock

fall mass movement

freeze thaw weathering shatters rock from cliff, gravity makes rocks fall to cliff base. forms talus/scree slopes

erosion

wearing away of land my wave action

types of erosion

hydraulic action, abrasion, attrition, solution

hydraulic action erosion

waves force water into cracks in cliff, air trapped & expands causing cracks to grow

abrasion erosion

waves throw sediment to cliff, scrapes causing further cracks/rocks to fall away

attrition erosion

sediment knocks each other causing the rocks to get smaller & smoother. doesn't affect the cliff

solution erosion

seawater reacts with some rocks, dissolving rock into it