EQ1: Why are coastal landscapes different and what processes cause these differences? Flashcards
How many people live on coasts at risk from flooding?
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.
What two main types can coasts be divided into?
Rocky (or cliffed) coastlines
Coastal plains (with no cliffs)
What is the difference between primary coasts and secondary coasts?
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
What is the difference between emergent coasts and submergent coasts?
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
What are the three types of tidal range?
Microtidal (tidal range of 0-2 m)
Mesotidal (tidal range of 2-4 m)
Macrotidal (tidal range greater than 4 m)
What is the difference between low energy and high energy coastlines?
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
What are the two main cliff profile types?
Marine erosion dominated
Subaerial process dominated
When do coastal plains form?
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.
What three elements are there to geological structure?
Strata
Deformation
Faulting
What is a concordant coast?
Concordant, or Pacific coasts, when rock strata run parallel to the coastline
What is a discordant coast?
Discordant, or Atlantic coasts, when different rock strata intersect the coast at an angle, so rock type varies along the coastline.
Why are headlands eroded more than bays?
The straight wave crests refract, becoming curved, spreading out in bays and concentrating on headlands
What are the two dominant geological characteristics that cliff profiles are influenced by?
The resistance to erosion of the rock
The dip of rock strata in relation to the coastline.
What are the four types of cliff profile?
Horizontal dip
Seaward dip high angle
Seaward dip low angle
Landward dip
What is the difference between permeable rocks and impermeable rocks?
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.
Why is permeability important in determining rates of coastal recession?
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.
How do plants contribute to preventing erosion of sediment on coasts?
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.
What is each step in plant succession called?
Seral stage
What is the end result of plant succession called?
Climatic climax community
What is the role of embryo dune pioneer plants in plant succession?
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.
Why are estuarine areas ideal for the development of salt marshes?
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.
