Page 41 - Year 9 Knowledge Organiser

Geography: Coasts: 5 of 6 Geography: Coasts: 6 of 6

Erosion Types Weathering Types
Eroded material is hurled or Freeze-Thaw Temperature changes causes water to freeze and then melt
Abrasion scrapes against the cliff, breaking widening cracks in rocks until they break. Transportation Types
off rock. Weathering (Mechanical) Deposition
Hydraulic Action Waves compress pockets of air in
cracks in a cliff, causing the crack Root Action (Biological) Seeds fall into cracks in rocks. These germinate and the roots 1. Traction Large rocks are rolled along the seabed. Description
to widen, breaking off rock. break the rocks open until they break.
Solution Cliffs e.g. chalk dissolve in Burrowing (Biological) Animals widen cracks in rocks. Smaller rocks are bounced along the seabed.
seawater. 2. Saltation
Eroded material in the sea, hit into Rainwater is slightly acidic due to dissolved CO . This reacts Material is dropped by the
2
Attrition each other breaking down into Acid Rain (Chemical with limestone rock causing it to dissolve. Smaller material/sediment is held in the waves due
smaller pieces. Weathering) 3. Suspension water. to a loss of energy and

The smallest silt and sediment is dissolved into velocity.
Headland and Bay Formation Cave, Arch, Stack, Stump Formation Wave Cut Platform Formation 4. Solution the water.

Application: Holderness Coastal Management Scheme
Reasons to protect Coastal Management Strategies Successes and Failures
1. Rocks are made of soft rock (boulder 1. 2 Rock groynes put in place at Mappleton to trap sediment being 1. Good – erosion in front of Mappleton has reduced, so
clay), eroding at 2m per year. transported by longshore drift, creating a wider beach to absorb the power the road has been saved.
2. The B1242 runs through Mappleton of the waves. 2. Bad – beaches further south have been starved of
and would be expensive to re-route. 2. Rock armour has been placed in front of the cliffs to absorb the wave sediment so erosion has increased e.g. at Great
energy. Cowden.