Characteristics and formation of coastal landforms 8.2

Question 1

Development of cliffs.

Answer 1

• Wave action undermines the land, leading to slumping and/or rock falls.
• Rapid and severe erosion occurs when large waves break against the foot of a cliff.
• This area is eroded to become a wave cut notch, undercutting the cliff face.
• The cliff will eventually collapse when the notch gets big enough.
• Wave cut platform is gently sloping at the base of the cliff.

Question 2

Headlands and bays.

Answer 2

• Form along coasts that have alternating resistant (harder) and less resistant (softer) rock and where the trend of the rock strata is at right angles to the direction of the coastline.
• Where there is harder rock, the coastline will be worn away less quickly leaving a headland that sticks out into the sea.
• Where there is softer rock, erosion will be more rapid and a bay will form.
• Wave refraction will concentrate erosion onto headlands where arches and stacks can form.

Question 3

Caves, arches and stacks.

Answer 3

• Corrasion and hydraulic action widen the joints in the rock to form caves on either side of the headland.
• If the line of weakness runs across the headland from side to side, two caves can meet to form a tunnel through the headland, a natural arch.
• Sub-aerial weathering and marine erosion eventually cause the arch to collapse, leaving a stack.
• The base of the stack continues to be eroded by the sea until it collapses, forming a stump.