TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Geography > Coastal Transportation
Coastal Transportation
- There are four different types of transportation and each one carries a different size load.
- Trachon - these are large boulders that are rolled along by the currents.
- Saltation - pebbles are bounced along by the waves and current.
- Suspension - small stones and sand carried within the water by currents and waves.
- Solution - particles dissolved within the seawater.]
Currents
Currents help to remove sediment from river estuaries and costal erosion; E.g. If there is no current at the end of a river a Delta might form. There is three types of currents;
- Longshore drift on the beach
- Longshore drift off the beach
- Rip Currents.
Longshore Drift on the Beach
- Beaches where waves approach at 90 degrees are called Swash Aligned Beaches and therefore there will not be much of longshore drift. Instead the material is transported up and down the beach. E.g. Storm Bay in Tasmania. Swash aligned beaches are rare and Longshore drift is the movement of sediment along the beach. When a wave breaks the swash carries the material up the beach in the direction of the wind. This is a diagonal movement up the beach then the backwash pulls material back down at a right angle due to gravity. This results in a zigzag migration of sediment along the beach by the processes of Saltation and Trachon called longshore drift. Material that is carried a long distance becomes smaller, rounder, and sorted according to its size. Longshore drift is dependent on the wind direction E.g. On the south coast of Britain the maximum fetch and prevailing wind are from the southwest so the drift is easterly.
- At Holderness Coast the maximum fetch and prevailing wind are from the northeast so therefore it moves south.
Longshore Current
- Is a current in the water beyond the influence of the waves where material is carried in suspension (mud and clay) along the coast in the same direction as the prevailing wind.
Rip Currents
- These are submarine currents formed where a ridge (sand / rock) runs parallel to the shore but contains gaps. As the tide retreats the water is funnelled through the gaps that are deepened and widened by abrasion and hydraulic action. Over time the rip currents will decrease in strength as the gap becomes wider and deeper.
Coastal Deposition
- Deposition occurs where the inputs exceed the outputs. Most features are shown below.
Comments
