Unit 5 Coastal Change and Conflict Flashcards
How are wave cut platforms formed?
Are fairly flat and rocky areas at the bottom of cliffs. Waves erode the coastline causing undercutting at the base of the slope. The notch gradually gets bigger, the rock above loses its support and collapses, debris is washed away by waves and them is repeated: making the cliff show retreat and get steeper
How are Headlands and Bays formed?
Always found together, a headland separates along a coastline. Their formation is affected by geology. Coastlines are made of different types of rock, the areas become weal, less resistant rock becomes headlands. This leaves an indent in the coastline. They are formed at discordant coastlines e.g. Swanage Bay
How are caves, arches and stumps formed
Cave- a cave is formed when the waves erode a weakness in the rock such as joint or fault
Arch- an arch form when two caves erode back from either side of a headland and meet in the middle.
Stack- more erosion with weathering makes the roof of the arch collapse and leaves an isolated stack
Stump- formed when a stack is eroded by wind and water
Describe the process of longshore dirt
Waves move towards the coast at an angle (due to the prevailing wind), as they break, swash carries material up and along the beach at the same angle. As the swash dies away, backwash and material fall at 90 degrees due to gravity. Material goes in a zig zag pattern. Sand is lighter than gravel so moves further up the beach
How is a bar formed
Sand and pebbles are moved along the coast by longshore drift. Where the coastline changes direction, sand and pebbles are deposited and this starts to build up until a spit is formed. Over time, the sand and pebble accumulation grows larger and builds across an estuary to form a bar. The bar cuts off rivers from the sea so water builds up behind the bar to form a freshwater lake or lagoon such as Slapton Ley in Devon
How is a spit formed?
When there is a bend in the coastline, long shore drift carries the sand beyond the bend. It builds up as a sand spit. Behind the spit, sheltered water becomes a salt marsh
How are tombolos formed?
A tombolo is a spit connecting an island to the mainland. An example is Chesil beach which connects Portland to mainland Dorest
How are coves formed?
- Waves cut slowly though a weakness in the resistant band of limestone caused by a river cutting a valley through limestone. This formed the small entrance of the cove
- Waves erode the soft band of clay quickly
- The band of chalk behind the clay band is more resistant so is slowing the rate of erosion inwards, although erosion is occurring sideways
Features of soft rock coasts
- High but less rugged and less steep than hard rock costs
- Will have piles of mud at the bottom of the cliff
- Will have very few hard rocks at the foot of the cliff
Features of hard rock costs
- High, steep and rugged
- Will have a bare face
- Will have some rocks and boulders at the end of the cliff
- Will have erosion features such as caves arches and stacks
What is a concordant coastline?
A CONCORDANT COASTLINE IS WHERE THE SAME ROCK RUNS ALONG THE COASTLINE
What is a discordant coastline?
A DISCORDANT COASTLINE IS WHERE THE ROCK TYPE ALTERNATES IN BANDS ALONG THE COASTLINE
