Transcript Coursework-Theory

Coursework Theory
section
Understand the Theories related
to the Fieldwork at Reculver on
the North Kent Coast.
Longshore Drift
Direction of movement
Backwash is always at
right angles to the beach
swash
Backwash
This movement of sediment along the coastline is
called longshore drift. This process occurs at the
fieldwork site (Reculver)
Destructive Waves
The backwash of the wave, due to the way in which it breaks on
the shore, is greater than the swash. This carries material away
from the beach.
Constructive Waves
The much lower wave breaks on the shore and the swash carries
material up the beach. The backwash is much weaker and cannot
carry the material away so the beach is built up.
Acid
cid
Corrosion
Hydraulic Action
Processes of Erosion
Attrition
Abrasion
•Abrasion/Corrasion
This is the process by which the coast is worn down by material carried
by the waves. Waves throw these particles against the rock, sometimes
at high velocity.
•Hydraulic Action
This process involves the force of water against the coast. The waves
enter cracks (faults) in the coastline and compress the air within the
crack. When the wave retreats, the air in the crack expands quickly
causing a minor explosion. This process is repeated continuously.
•Corrosion
This is the chemical action of sea water. The acids in the salt water
slowly dissolve rocks on the coast. Limestone and chalk are particularly
prone to this process.
•Attrition
Material carried by the waves bump into each other and so are smoothed
and broken down into smaller particles.
Wave cut platform and cliff retreat
Important
The processes by which
this feature forms are not
dominant at the field
work site at Reculver.
 The waves attack the base of the cliff through the processes of
abrasion, corrosion, hydraulic action and attrition.
 Over time the cliff will be undercut and a wave-cut notch is formed.
 Eventually the cliff becomes unstable and collapses. Further cliff
retreat will form a wave-cut platform.
Cliff retreat at Reculver
1. Rain
3. Gravity causes
the, now heavy, cliff
to collapse.
2. The material of
the cliff soaks up
the rainfall.
4. High tides and
storm waves will
transport the cliff
debris out to sea.
5. The cliff debris
offers some
protection, to the
cliffs behind, from
storm waves.
SEA
Spring sapping at Reculver
1. Rain
5. The cliff is
undercut by the
spring sapping
which encourages
cliff collapse and
retreat.
2. Rainfall
percolates through
the cliff
3. It emerges at the
base of the cliff
4. Small particles of
sand swept out
from the cliff by the
spring water.
SEA