Coastal Landforms 42/43 Flashcards
what is a discordant coastline
a coastline made up of alternating bands of hard and soft rock at right angles to the coast
what is a concordant coastline
alternating bands of hard and soft rock which are parallel to the coast
name 3 rocks and there erosion
sedimentary- easy to erode
metamorphic- difficult to erode
igneous- difficult to erode
how’s a spit formed
by longshore movement of sediment
-form at a sharp bend in the coastline (e.g river mouth)
whats differential erosion
erosion at different speeds
how’s a bar formed
when there is a gap in the coastland with water in it
-forms when a spit joins 2headlands together
what’s the formation of sand dunes
when wind deposits sand on top of each other until a small mound starts to form
use an example of a UK coastline to identify major landforms of erosion and deposition.
Lyme regis
-built a new sea wall with rock armour
factors which influence the speed of erosion
-rock type
-fetch of wave
-weather
-human effects
-defence systems; sea walls to slow down erosion
What forms alongside a discordant coastline
-headlands and bays
where there are alternating bands of resistant and less resistant rock along a coast
-less resistant rock is eroded quicker forming a bay
-bc resistant rock erodes more slowly, it juts out forming a headland with steep sides
what is formed when a headland is eroded
-caves
-arches
-stacks
explain the process of headlands and bays
- form when alternating bands of resistant and less resistant rock are along the coast
- less resistant rock (clay) is eroded quickly by water, forming a bay (gentle slope)
- hard resistant rock is eroded more slowly and is left jutting out, forming a headlands (steep side)- headlands have steep sides
which type of rock has a low resistance to erosion
-soft rock/rocks with lots of joints
which type of rock has a high resistance to erosion
hard rocks with solid structure
what is headlands weeknesses that mean they can form caves arches and stackes
theyre made from resistant rock and have weaknesses like cracks
How do
-caves form
-arches form
-stacks form
-waves crash into headlands and enlarge the cracks by hydraulic power and abrasion
-REPEATED erosion and enlargement of the cracks causes a cave to form.
-continued erosion deepens the cave until it breaks through the headland forming an arch
-erosion continues to wear away the rock supporting the arch, until it collapses forming a stack, an isolated rock separate from the headland
waves erode cliffs to form….
wave-cut platforms
what is a wave cut platform
a wide, gently sloping surface found at a cliff base and extends into the sea
where do waves cause the most erosion
at the foot of a cliff
explain the process of a wave cut platform
- erosion occurs at foot of cliff
- wave cut notch formed and erosion continues
- rocks above notch become unstable and collapse
- collapsed material is washed away and new notch forms
- as the process repeats, cliff retreats
how are beaches formed
by deposition
explain how a sand beach is created
-by low energy waves
-they’re flat and wide
-sand particles are small so the weak backwash can move them back down the beach
explain how a shingle beach is created
-by high energy waves
-they’re steep and narrow
-sand particles are washed away but larger shingles left behind
state what deposited sediment forms
-spits
-bars
-sand dunes
