Geological Structure & Rock Type
- The coast can be defined as the meeting point between the land and sea
- Coastal processes are divided into two parts:
- Marine processes: Offshore (water-based)
- Terrestrial processes: Onshore (land-based)
- These processes are further divided into:
- Wave action
- Erosion
- Transportation
- Weathering
- Mass movement
- Together with the local geology, these processes produce distinctive landforms around the coastline
- A coastline made up of softer rocks such as sands and clays will be easily eroded by destructive waves to form low, flat landscapes such as bays and beaches
- Coastlines of more resistant, harder rock will take longer to erode and produce rugged landscapes such as headlands
- Joints and faults expose rock to erosion and weathering
- The differences between hard and soft rocks will also impact the shape and characteristics of cliffs
The Effects of Rock Type on the Coastline
|
Hard Rock |
Soft Rock |
Shape of cliff |
High and steep |
Generally lower and less steep |
Cliff face |
Bare rock and rugged |
Smoother; evidence of slumping |
Foot of cliff |
Boulders and rocks |
Few rocks; some sand and mud |
- Concordant coastlines are made up of the same rock type, running parallel to the sea, these coastlines produce coves
- Discordant coastlines have alternating bands of rock perpendicular to the sea, these types of coastlines form headlands and bays
- Geology, therefore, shapes the coastline vertically through the height and profile of a cliff and horizontally with bays and headlands
Exam Tip
Make sure you know the difference between the four types of erosion, particularly between abrasion (corrasion) and attrition. So many students confuse these two terms. A tip for you, is to think of abrasion as rubbing with sandpaper or maybe you have grazed your knees or elbows when you fell off your bike/skateboard? Those grazes were abrasions on your knees/elbows etc.