DL - Jurassic Coast Case Study

Location

• South Coast of UK

• Exmouth in Devon to Poole in Dorset

• 96 miles long

• Formed during Jurassic Period

How has Climate and Weather impacted the landscape?

Temperature

• Summer temperature is 21C and Winter is 3C.

• Limited freeze thaw weathering.

• Salt weathering dominates.

Wind

• Southwesterly prevailing wind brings storms.

• Increases hydraulic action and abrasion which undercuts cliffs and promotes mass movement

Rain

• Makes rocks heavier which promotes mass movement.

• Cliffs collapsed after Storm Frank in 2016.

How has Geology impacted the landscape?

• Bands of hard and soft rock

• Soft rock easily eroded and weathered

• Forms cliffs, bays, headlands, beaches etc.

How have Climate, Weather and Geology interacted to impact the landscape?

• Lots of rain make chalk and limestone vulnerable to chemical weathering due to acid rain

• Clay becomes heavy, softer and more slippery after heavy rain. During winter, slumps and slides on clay cliffs.

How have industry and tourism impacted the landscape?

• Quarrying for gravel in Chesil Beach.

• Walking wears down footpaths exposing underlying rock to weathering and erosion

List of landforms

• Durdle Door

• Chesil Beach

• Old Harry and his Wife

Durdle Door

• Arch

• Formed on Portland limestone headland

• Waves open crack to become cave (hydraulic action + abrasion); cave breaks through headland

• Arch being broken down by chemical, mechanical and biological weathering

Chesil Beach

• Tombolo

• Joins Isle of Portland to the mainland

• Change in direction of headland — longshore drift deposits material as a spit

• Spits joins w Island forming tombolo

Old Harry and his wife

• Headland to stack to stump

• Chalk Headland Arch collapsed to form stack and stump

• Hydraulic, abrasion, salt weathering, carbonation, biological weathering continue

Swanage Bay

• Softer clay between hard chalk and limestone

• Erosion continues and material is lost

• Cliff unstable in parts and prone to slumps

Lulworth Cove

• Small bay, eroded in band of Portland limestone.

• Clay behind was softer, Eroded by hydraulic action and abrasion back to chalk cliffs.

• Cliffs prone to slides and slumps

Coastal management methods (Swanage Beach)

• Groynes

• Sea walls

• Beach replenishment

Groynes

• Wooden fence built perpendicular to the sea.

• 18 timber groynes placed from 2005-2006

• Prevents longshore drift — no sand and sediment can travel down the coastline preserving the current beach

• Damage would be £35 million - ugly, deters tourists

• North end of beach is narrowing so no transport

Sea walls

Sea walls built along sea front. Built in 1920s

Placed at bottom of cliffs to stop erosion. Curved to reflect energy

• protects base of cliff

• promenades

• 5k per metre

• sea wall can be eroded

• does not protect beach, beach replenishment needed

Beach replenishment

Sand is added to beach.

• protects sea wall

• blends in; natural landscape

• makes beach wider; attracts tourists

• kills sponges/ corals on sea bed