EQ1: Why are coastal landscapes different? What processes cause the differences? GapFill

Waves are formed by the wind blowing across the surface, which causes friction and, therefore, drag.   CurrentDriftShorelineFetch is the distance the wind has blown across the sea.  The greater the distance, the greater the energy that the wave has.  If the wind mainly blows in one direction, called the  prevailingoffshoreonshorecommon wind, it will have more energy than if the wind constantly changes direction.

In a wave, the water moves forward, but it does so in a  spillingcircularonshorelinear movement, almost as a spiral, as successive waves move across the water and the water bobs up and down.  The motion is much greater at the surface than at depth.

Currents affect the movement of water and sediment along the coast.  Offshore currents (  riponshorelunartidal currents) transport material out to sea, while longshore currents run along the coast and transport material eroded in one part downstream.

 Spilling wavesTidesWavelengthsWaves are the daily rise and fall of the sea level at the coast.  The difference between the high and low tide each day is called the tidal range.  There are usually  onetwofourthree each of low and high tides per day.  The greater the tidal range, the more coastline is affected by waves and, therefore, by erosion and deposition.

Tides are caused by the gravitational pull of the Moon and, to a lesser extent, the Sun.  When the Sun and Moon are aligned, their gravitational pull combines and the tides are  increasinglowerhigherunchanged, with the greatest tidal range.  These are called spring tides.  When the Sun and Moon are at right angles, the pull is reduced as the pull is partially cancelled.  The  decreasingequalhighestlowest tidal ranges are called neap tides.

We can classify coastlines based on their energy.  Low-energy coastlines are sheltered places like  rocky shoresestuarieslong-fetch coastsislands.  Waves are less powerful, meaning that there is more deposition than erosion, so there are more constructive features such as beaches and spits.  In high-energy coastlines, powerful waves cause erosion; for example, where there is a large fetch on the western coast of the UK.  High-energy coasts often have  rockyshelteredlagoon-typesandy coastlines with lots of erosional features.

Geology shapes the coastline.  Rocks are of different hardnesses and erode at different rates.  The softest (and fastest to erode) are the  unconsolidatedlimestonegranitecompressed materials, followed by sedimentary rocks.  Metamorphic rocks and igneous (volcanic) rocks erode very slowly.  Rocks can also have cracks, faults and joints. The more cracks there are, the greater the potential for erosion.

On  concordantsandyrockydiscordant coastlines, the bands of rock are parallel (aligned) with the coast.  If the sea manages to break through a hard layer, or a river flows to the sea creating an opening, erosion will continue behind to form  a covea beachan archa cliff, sometimes with a narrow opening.

On  sandydiscordantrockyconcordant coastlines, the bands of rock are at angles to the sea.  Each type of rock is exposed to the erosive power of the waves – so they all erode at the same time, but at different rates.  The  unconsolidatedresistiveweakjointed rocks will erode more slowly, forming headlands.  Between the headlands, there is more erosion, so bays form.  The shelter of the bays means that deposition can occur.