Dorset landforms (deposition) #7 Flashcards
How long has it taken for Hurst Castle spit to form?
A millennia
How has Hurst castle spit formed?
Due to LSD from mass movement on cliffs in Christchurch, fluvial sediment from river in harbour and offshore banks.
If the coastline changes direction what happens to LSD?
Continues in a straight line causing deposition.
How else could the spit have formed?
From big storms and glaciers.
What has caused the distinctive curve of the spit?
The proximity to the Isle of Wight causes waves to change direction.
What does the curve protect?
Salt marshes behind.
How long is the tombolo at Chesil Beach?
18km
What does the tombolo connect?
Isle of Portland with a lagoon behind.
What needs to be kept constant for tombolos to be maintained and how does this occur?
Constant LSD provided by weak lithology and a concordant coastline with no interruptions of bays and headlands.
How and where do beaches form (e.g. Bournemouth)
They form in front of areas with weak lithology (greensands) where rock is eroded quickly and provides a lot of sediment.
What influences beach profile?
type of material (shingle=steeper as higher perc. so less backwash) and angle of strata (sea dipping=gently sloping)
