Coastal landscapes and Landforms

:Landscape is the big picture- sea, coast, rolling landscape

:Landforms are the individual components of the landscape- cliffs, beaches, wave cut platforms

a) Landforms created by Erosion

1. HEADLAND + BAYS

Headlands and bays most commonly form along discordant coastlines. Discordant coastlines form where geology alternates between bands of hard and soft rock .

These forms due to different rock types and only occur where soft and hard rock are found at right angles to the sea- discordant

Soft rocks erode more quickly and form bays. Whereas, hard rocks are more resistant and forms headlands.

1. CLIFFS + WAVE-CUT PLATFORMS

When waves break against the foot of a cliff, erosion (hydraulic action and corrosion in particular) tends to be concentrated close to the high-tide line. This creates a wave-cut notch. As the notech gets bigger, the cliff is undercut and the rock above it becomes unstable, eventually collapsing it.

As these erosional processes are repeated, the notch migrates unland and the cliff retreats leaving behind a gently sloping wave-cut platform. Which is usually only completely exposed at low tide. Wave-cut platforms rarely extend for more than a few hundred metres, because a wave will break earlier and its energy will be dissipated before it reaches the cliffs, thus reducing the rate of erosion, limiting the further growth of the platform. This is another excellent example of a negative feedback.

3. CAVES, ARCHES, STACKS AND STUMPS

As headlands jut out into the seas they are more exposed to erosion by waves. Hydraulic action (the force of the water eroding rock) will attack cracks (areas of weakness) in the rock widening them. The cracks will be continuously widened until over time they form a cave as they have been eroded backwards by corrosion (rocks in the water hitting off the back wall and eroding it). Continued corrosion and hydraulic action on both sides of a cave leads to it cutting through the headland completely to form an arch. The rocks at the base of the arch will be attacked by the waves and widened which in time leads to the top of the arch being unsupported and unstable, so that it will eventually collapse. This leaves a column of rock standing alone in the sea which is called a stack. This can be eroded further until it collapses leaving a stump.

FAULTLINE

CAVE

ARCH

STACK

STUMP

HOW HAS THE LANDFORM BEEN CREATED?

Joint or fault in resist rockwaves attack area of weakness by corrosion, erosion and hydraulic action, wave quarrying

This cave forms in a headland. It is corrosion and hydraulic action by the waves attacking the weakness in the cliff

The arch is formed by the waves cutting through the headland. The base is continuously widened

Stack is formed from the arch which becomes ypp heavy to be supported and collapses due to gravity

Stump is created from a stack which collapses. Hydraulic action and abrasion attacks the stump.

WHAT WILL HAPPEN OVER TIME?

This will eventually form a…