1.3 - Discordant Coasts And Geological Structure

Question 1

What is a discordant coast?

Answer 1

When the layers of rock are perpendicular to the coast

Question 2

How do SLR and the structure determine what landforms are created?

Answer 2

Alternate layers of soft and hard rock
Soft rock gets eroded from SLR due to erosional processes e.g. hydraulic action
Hard rock resists erosion, forming headlands
More fetch and/or exposure (e.g. due to orientation) speeds thus up

Question 3

Role of wave refraction?

Answer 3

When approaching coast, friction due to shallower seabed increases so wave height increases
In bays, wave crests curve to fill bay so height decreases
At headlands, refraction occurs so more energy concentrated at headland then spread out, so erosion is reduced and erosional headland material is deposited at bays

Question 4

Role of tectonics?

Answer 4

Push up seabed to form coastline
Plate collisions fold rock creating weakened parts
Magma rises and cools = igneous
Sea removes layers to expose resistant igneous rock

Question 5

How does wave refraction change morphology?

Answer 5

Headland erosion so morphology straightens out

Sediment deposited at bays = beach

Question 6

How does SLR affect morphology?

Answer 6

Bays become longer and narrower as rock is soft and in more contact as SL rises