geography!

• coast = where land meets sea
• waves are formed by the wind blowing across the surface of the sea, creating friction
• fetch = the distance over which the wind has blown
• the longer the fetch the greater the wave
• what happens when waves reach the coast?

  they travel with a circular orbit in open water -> friction with seabed distorts circular orbit -> the crest of wave starts to move faster (increasing elliptical orbit) -> wave breaks
• swash = the water that rushes up the beach after a wave has broken
• backwash = the water that retreats and flows back into the sea after a wave has broken
• constructive wave:

  low wave height (1m)

  strong swash -> deposits material

  weak backwash

  long wave lengths (8-10 per minute)
• destructive waves:

  tall wave heights (over 1m)

  weak swash

  strong backwash (erodes beach)

  short wave lengths (10-14 per minute)
• factors affecting coastlines:

  geology, human activity, climate seasonal variations, extreme weather, transportation, sediment, types of waves
• how GEOLOGY affect coastlines:

  coastlines are made up of different rock types

  hard rock (resistant) + soft rock (less resistant)

  -> coasts shape depends on how easily rock can be eroded
• how HUMAN ACTIVITY affects coastlines:

  increased amount of visitors (to coast) increases footpath erosion
• how CLIMATE + SEASONAL VARIATION affects coast:

  summer -> attracts visitors

  winter -> brings in destructive waves + heavy storm-like conditions
• how EXTREME WEATHER affects coast:

  eg, storm surges -> puts pressure on coastline due to amount of material eroded

  -> dramatically changes coastal environment
• how TRANSPORTATION affects coastlines:

  some beaches that have less transportation are ‘starved‘ (little sediment build-up) & more transportation has more build-up
• how TYPES OF WAVES affect coast:

  constructive: build on coastline

  destructive: erode coastline
• sediment = solid material that is moved + deposited in a new location
• transportation = the movement of material in the sea and across the coast by waves
• longshore drift = the movement of material along the coast
• rock + wooden grounds are used to stop longshore drift from taking place
• prevailing wind = dominant wind direction
• groynes can affect locations further down the coastline (doesn’t prevent erosion)
• traction = when boulders are pushed along the sea bed
• Saltation = when small pebbles are bounced along the sea bed
• Suspension = when small particles are carried along in the water
• solution = when soluble material has been dissolved in the water
• erosion = the wearing away of material
• Hydraulic action (coast) = when water compresses air into gaps, causing them to expand
• abrasion = when eroded particles are hurled against the coastline, wearing it away
• attrition = when eroded particles smash into eachother, breaking into smaller pieces
• Solution = when rock is dissolved (carbonic acid)
• what influences the rate of erosion:

  fetch, strong winds, coastal landscapes, geology
• beach = found on coasts between high and low tide level
• a beach profile shows the gradient from the back of the beach to the sea and the characteristics in between
• low tide = sea is further out
• high tide = sea is closed
• backshore = the back of the beach
• foreshore = front of the coastline
• offshore = off the coast
• Pebble beaches:

  larger sized sediment

  Backshore sediment is larger than foreshore

  Typically narrow + steep

  destructive waves