Erosion Landforms: Headlands and Wave-Cut Platforms Flashcards
What erosional processes are involved in the formation of a stump?
Hydraulic action, abrasion and solution.
What is the first step in the formation of a stump?
Firstly, the sea attacks the foot of the cliff and begins to erode areas of weakness such as joints and cracks, through processes of erosion such as hydraulic action, abrasion and solution.
What is the second step in the formation of a stump?
Gradually these cracks get larger, developing into small caves.
What is the third step in the formation of a stump?
Further erosion widens the cave and where the fault lines runs through the headland, two caves will eventually erode into the back of each other forming an arch, passing right through the headland.
What is the fourth step in the formation of a stump?
A combination of wave attack at the base of the arch, and weathering of the roof of the arch (freeze-thaw weathering, wind and rain), weakens the structure until eventually the roof of the arch collapses inwards leaving a stack, a column of rock which stands separate from the rest of the headland.
What is the fifth step in the formation of a stump?
The stack continues to erode, eventually collapsing to form a stump which may be covered by water at high tide.
What is the landform that is eroded into a stump?
A stack.
How does the arch collapse in the formation of a stump?
Under its own weight and gravitational pull.
What type coastline are headlands and bays formed on?
Discordant coastlines.
Why are headlands and bays only formed on discordant coastlines?
As the alternating bands of soft and hard rock perpendicular to the coastline means that the hard rock can be eroded slower than the soft rock will be.
What is the first step in the formation of headlands and bays?
Firstly the coastline’s headlands and bays are formed as it is a discordant coastline with alternating bands of harder and softer rock.
What is the second step in the formation of headlands and bays?
Both bands of harder and softer rock are eroded by hydraulic action (air is trapped into the cracks and pores, causing pressure to build, breaking the rock) and abrasion (grinding of rock against the base of the cliff).
What is the third step in the formation of headlands and bays?
Softer rocks are eroded first because they are less resistant so erode at a faster rate, creating bays.
What is the fourth step in the formation of headlands and bays?
Harder rocks are eroded second, because they are more resistant so erode at a slower rate, creating headlands that are left jutting out in the sea, vulnerable to further erosion.
What type of rock erodes faster than the other?
Soft rock.
