Case studies for 1.1.4

Question 1

What places on the South Purbeck coast represent the five stages of landform development on a concordant coast line?

Answer 1

1. Stair Hole
2. lulworth cove
3. Durdle Door
4. St Oswald’s Bay
5. Worbarrow Bay

Question 2

Explain stage one of landform development on a concordant coastline

Answer 2

Stair hole:
. embryo cove
. tectonic activity caused intense folding of limestone which weakens the coast (limestone easier to breach)
. clay behind has been laterally eroded quicker

Question 3

Explain stage two of landform development on a concordant coastline

Answer 3

Lultworth cove:
.200,000 years later than stair hole
.marine and fluvial erosion acting on it
. here the sea has exploited a periglacial river valley
. chalk (harder rock) at the back of the cove behind the clay slows down the erosion
. clay laterally eroded to form a cove

Question 4

Explain stage three of landform development on a concordant coastline

Answer 4

Durdle door
. eustatic sea level rise meant that the sea attacked lines of weakness such as joints and bedding planes breaking through the limestone
. differential erosion and wave refraction causes coves to form and attacks from both side to form caves and arches- weathering and mass movement=roof of arch collapses

Question 5

Explain stage four of landform development on a concordant coastline

Answer 5

St Oswald’s bay
.Double bay
.once clay was eroded to the chalk, erosion continued from east to west through lateral erosion until becoming a double bay
.remnant of limestone headlands now stacks
. weathering and mass movement eroded archs into stacks and then stumps- such as Man-o-war rocks

Question 6

Explain stage five of landform development on a concordant coastline

Answer 6

Worbarrow Bay
. chalk headland has eroded back further leaving wider bay
.Dry river valley called Arish Mell developed in periglacial times=extra fluvial processes acting on it from landward side
.used to be an isalnd in the middle of the bay but once it eroded there was a double bay.

Question 7

Where is the purbeck coast?

Answer 7

South of England in dorset