EQ1: Why are coastal landscapes different and what processes cause these differences?

Question 1

How many people live on coasts at risk from flooding?

Answer 1

Over 1 billion people live on coasts at high risk from flooding and about 50% of the world’s population lives within 200 km of the coast.

Question 2

What two main types can coasts be divided into?

Answer 2

Rocky (or cliffed) coastlines

Coastal plains (with no cliffs)

Question 3

What is the difference between primary coasts and secondary coasts?

Answer 3

Primary coasts are dominated by land-based processes, such as deposition at the coast from rivers or new coastal land formed from lava flows

Secondary coasts are dominated by marine erosion or deposition processes

Question 4

What is the difference between emergent coasts and submergent coasts?

Answer 4

Emergent coasts where the coast is rising relative to sea level, for example as a result of tectonic uplift

Submergent coasts are being flooded by the sea either because of sea level rise and/or subsiding land

Question 5

What are the three types of tidal range?

Answer 5

Microtidal (tidal range of 0-2 m)

Mesotidal (tidal range of 2-4 m)

Macrotidal (tidal range greater than 4 m)

Question 6

What is the difference between low energy and high energy coastlines?

Answer 6

Low energy sheltered coasts with limited fetch and low wind speeds resulting in small waves

High energy exposed coasts, facing prevailing winds with long wave fetches resulting in powerful waves

Question 7

What are the two main cliff profile types?

Answer 7

Marine erosion dominated

Subaerial process dominated

Question 8

When do coastal plains form?

Answer 8

Sea level falls

Sediment brought from the land by river system is deposited at the coast causing coastal accretion so coastlines gradually move seaward, such as a river delta

Sediment is moved from offshore sources (sandbars) towards the coast by ocean currents.

Question 9

What three elements are there to geological structure?

Answer 9

Strata

Deformation

Faulting

Question 10

What is a concordant coast?

Answer 10

Concordant, or Pacific coasts, when rock strata run parallel to the coastline

Question 11

What is a discordant coast?

Answer 11

Discordant, or Atlantic coasts, when different rock strata intersect the coast at an angle, so rock type varies along the coastline.

Question 12

Why are headlands eroded more than bays?

Answer 12

The straight wave crests refract, becoming curved, spreading out in bays and concentrating on headlands

Question 13

What are the two dominant geological characteristics that cliff profiles are influenced by?

Answer 13

The resistance to erosion of the rock

The dip of rock strata in relation to the coastline.

Question 14

What are the four types of cliff profile?

Answer 14

Horizontal dip

Seaward dip high angle

Seaward dip low angle

Landward dip

Question 15

What is the difference between permeable rocks and impermeable rocks?

Answer 15

Permeable rocks allow water to flow through them, and include many sandstones and limestones.

Impermeable rocks do not allow groundwater flow and include clays, mudstones and most igneous and metamorphic rocks.

Question 16

Why is permeability important in determining rates of coastal recession?

Answer 16

Groundwater flow through rock layers can weaken rocks by removing the cement that binds sediment in the rock together. It can also create high pore water pressure within cliffs, which affects their stability.

Question 17

How do plants contribute to preventing erosion of sediment on coasts?

Answer 17

Roots bind sediment particles together making them harder to erode.

When submerged, plants provide a protective layer so the sediment surface is not directly exposed to moving water and erosion.

Plants protect sediment from erosion by wind, by reducing wind speed at the surface because of friction with the vegetation.

Question 18

What is each step in plant succession called?

Answer 18

Seral stage

Question 19

What is the end result of plant succession called?

Answer 19

Climatic climax community

Question 20

What is the role of embryo dune pioneer plants in plant succession?

Answer 20

Stabilise mobile sand by their root systems

Reduce wind speeds at sand surface, allowing more sand to be deposited

Add dead organic matter to the sand, beginning the process of soil formation.

Question 21

Why are estuarine areas ideal for the development of salt marshes?

Answer 21

They are sheltered from strong waves, so sediment (mud and silt) can be deposited

Rivers transport a supply of sediment to the river mouth, which may be added to by sediment flowing into the estuary at high tide.