Geography - Coasts (features and processes)

• Weathering

  what is it

  weakening of rock by natural processes which make erosion easier
• weathering

  name the three types of weathering

  1 biological

  2 physical/freeze thaw

  3 chemcal
• weathering

  describe what happens during biological weathering

  The roots from trees and plants go into the rock making erosion easier as they form small cracks. The roots weaken the structure and starts breaking the rocks.

  The roots burrow down, weakening it until it breaks away

  1 plant roots can get into small cracks in the rocks

  2 as the roots grow the cracks become larger

  3 this causes small parts of the rock to break away

  
• Weathering

  describe the process of physical/freeze-thaw weathering

  freeze-thaw weathering occurs when rocks are porous (have holes) or are permeable (allow water to pass through)

  1 the water enters the cracks in the rock

  2 when temperature drops the water freezes and expands causing the crack to widen

  3 the temperate decreases and the ice melts and water makes its way deeper into the cracks

  4 the process repeats again and again until the rock splits entirely

  
• weathering

  describe the process of chemical weathering

  rainwater and seawater can be a weak acid. If a coastline is made up of rocks such as limestone or chalk, overtime they can become dissolved by the acid in the water

  A) chemical weathering erodes the rock

  
• erosion

  what is it

  the process where rocks are broken down by natural forces such as wind or water
• erosion

  name one of the processes of erosion

  hydraulic action

  this occurs as the waves hit the cliffs that have a lot of cracks, the wave then hits the gap and the water goes further in. The air also goes further into the gap making it even bigger. Cliff material is removed and falls away

  
• erosion

  describe and explain the 4 parts to hydraulic action

  1 waves crash against the holes in the cliff, the air in the cracks is forced further into the cliff, as they widen the cliff breaks open and falls into the sea

  2 attrition - the fallen rocks in the water get moved by the tide and hit together and then break into small pieces. They get smaller and smaller over time

  3 abrasion - waves have small sediments in with the water, as the waves hit the cliff, the sediment abrades the cliff removing part of it

  4 cliff retreat - overtime, the cliff moves back and land is lost

  
• erosion

  features of erosion

  describe what happens to the soft and hard rock at coastlines


  this erosion causes headlands and bays

  1 the hard rock is more resistant to erosion as it is harder to erode, the hard rock bands to stick out more than the soft rock

  2 the soft rock is less resistant and therefore erodes quicker (this is a bay) at areas of soft rock, they contain a beach with deposited sand.

  these bands of hard rock and soft rock alternate meaning that the cliffs are eroded more at the soft rock bands and less at the the hard rock bands

  
• erosion

  cave, arch and stack

  describe what happens at each stage of cliff erosion

  1 waves retract around the headland (hardrock) where there are small cracks as the roots go into the rocks making erosion easier

  2 a cave starts to form through erosion

  3 an arch starts to form and you can see through it

  4 the arch falls down to make a stack

  5 the stack then erodes and falls to form a stump

  
• what is attrition

  when material such as rocks and stones carried by waves hit and knock against each other wearing them down

  
• what is abrasion

  when rocks and other materials carried by the sea are picked up by strong waves and thrown against the coastline causing more material to be broken off and carried away by the sea.