Dorset landforms (erosion) #6 Flashcards
How was Lulworth Cove formed?
The sea has broken through narrow band of:
v.resistant Portland rock
eroded Purbeck Beds
wealden beds
weak greensand
very quickly to the resistant chalk at the back.
What else could have contributed to erosion of lulworth cove?
Fluvial erosion from river networks formed as chalk froze and became impermeable in periglacial period.
What is the geology of Purbeck beds
Clay, shale and limestone
What is the geology of Wealden beds
Sands and clays
What is the geology of Greensand
Sandstone
Why is the cove circular
Wave refraction through the 2 headlands
How did the stair hole (geo) form?
Sea broken through Portland stone via 2 arches and rapidly erodes Purbeck beds behind
How did Durdle Door (arch) form?
Sea broke through resistant Portland Stone and rapidly erodes Purbeck beds behind.
How did Old a Harry’s rock (stack of chalk) form?
Formed as top of arch collapses- weathering and aeolian processes
Where is the wave cut platform?
In front of limestone cliffs near Durlston head.
How do caves form e.g near Durdle Door at Lulworth form?
Intense folding creates cracks and weaknesses, these have been exploited forming caves, attrition and hydraulic action.
What are the cliffs like at Christchurch Bay?
Low cliffs 20-30m high
what is the geology of Swanage bay?
Limestone on either side with less resistant sands, clay and shale making up bay.
Why does deposition occur at Swanage bay?
waves are at low energy between the 2 headlands and differing angles of bedding plain between headland and bay.
Name a headland in Dorset?
Studland headland
