Coasts EQ1 Flashcards
Describe plant succession
Where vegetation in a coast changes over time, pioneer species colonise bare sand or mud to climax seral stage
what is a haff coastline
Where long ridges of mud and sand form parallel to the coastline, with lagoons (haffs) behind them
How does the pioneer plant change the conditions of the soil
*By adding humus
*Retaining moisture
*Stabilising loose sand or mud
Explain how a salt marsh forms.
Mixing of Fresh water and sea water in the estuary causes floccolation. Then algae colonises mud at low tide. The algae stabalises the environment. Then the mud is covered by the tide for less time. Now, halophytic plants colonise. Then sediment raises the height of the marsh which allows hardy plants to colonise.
What is flocculation
Tiny clay particles that stick to one another
What is a dalmatian coastline
Sea level change –> Valleys and ridges run parallel to eachother –> valleys are flooded –> ridges remain above the surface as a series of offshore islands.
Where do we find salt marshes
Estuarines and sheltered bays and spits
How does algae stabilise salt marshes
By binging mud, adding organic matter, and trapping sediment.
How does vegetation stabilise coastal sediment?
- the 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 windspeed at the surface because of friction with the vegetation
What are erosion and weathering influenced by?
Erosion and weathering are influenced by:
* how reactive minerals in the rock are when exposed to chemical weathering
* whether rocks are clastic or crystalline - the latter are more erosion-resistant
* the degree to which rocks have cracks, fractures and fissures, which are weaknesses exploited by weathering and erosion
What are subaerial processes?
Subaerial processes include weathering processes, mass movement processes and surface runoff erosion, with these leading to the changing shape of the coastline
What is a haloseres
Salt marshes
What is fetch?
Fetch is the uninterrupted distance across water over which a wind blows - and therefore the distance waves have to grow in size.
What is the role of salt marshes?
Absorb coastal flooding
What is humus
Decayed vegetation
What is a psammosere?
Sand dunes
What is xerophytic plants
Plants such as marram grass that can survive with little fresh water.
What are halophytic plants?
Plants such as samphire that can survive in salty conditions.
What is the role of sand dunes?
Taking the impact of storms.
How can coasts be classified based on their wave energy?
Coasts can either be:
* 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 some Wave characteristics to think about.
The energy of the wave - size,shape, length of fetch, prominent prevailing wind, and the depth nearshore and offshore water.
What is a salt marshe
coastal ecosystem found between land and open salt water or brackish water that is regularly flooded by the tides
What is unconsolidated material?
Unconsolidated material is sediment that has not been cemented to form solid rock - a process known as lithification.
Give some examples of Concordant coast ( dalmatian)
Eastern coast of the Adriatic sea or isle of purbeck
What are some Geology characteristics to think about.
Resistance to erosion and weathering, the degree of consolidation, number of joints and bedding planes and amount of folding.
What is the definition of bedding planes
horizontal cracks - breaks in the strata caused by gaps in time during periods of rock formation
What is a dip
Angle at which the rock strata lie.
why do coastlines advance and retreat
Coastlines advance due to the land emerging or deposition
Coastlines retreat due to the land submergine and erosion
What are some characteristics of igneous rock?
▪ very resistant
▪ annual erosion rate of 1mm
▪impermeable
Describe the waves, processes and landforms of a high energy coast and general locations
Wave: destructive waves - waves, storm conditions and long fetches
Processes: the rate of erosion exceeds the rate of deposition
Landforms:headlands, cliffs, shoreline platforms
Cornwall or North Western scotland
What is perviousness
How well water flows through cracks and joints in rock
What is the definition of lithology
The physical characteristics of particular rocks
What are the long term criteria which affect coasts
▪Sea level change
▪Geology
What is the definition of Folds
Where the strata has been bent or curved due to pressure from tectonic activity
What are some characteristics of unconsolidated material rock?
▪ Annual recession of 1m per year
▪ Permeable
What is the definition of morphology
The shape and form of coastal landscapes and their features
What is the definition of coastal recession
Another term for coastal erosion
What is porousness?
How well water flows between the pores/gaps in between the grains of rock
Why are folds more easlity eroded
Because they are often fissured and jointed
Give some examples of disconcordant coast (Atlantic)
South-west Ireland or Isle of purbeck or southern Chile.
What are some characteristics of metamorphic rock?
▪ Very resistant
▪ Annual recession of 2.5cm
▪ Impermeable
What are the short term criteria which affect coasts
▪wave energy
▪wave type - constuctive, destructive
Describe the waves, processes and landforms of a low energy coast and general locations
Waves: constructive waves, calmer conditions and short fetches.
Processes:deposition and transport
Landforms:beaches, spits, salt marshes, sand dunes, bars and mudflats
Lincolnshire and Northumberland
What is the definition of faults
Faults are major fractures in rock created by tectonic forces, with displacement of rocks either side of the fault line.
What is a disconcordant coastline?
Where the folding or arrangement of rock is perpendicular to the coast
What are folds
Folds are bends in the rock
What is the definition of Strata
Layers of rocks
What happens to rocks either side of the fault line
Displacements
what are the inputs, processes and outputs of a coast in a system.
Inputs: Marine - waves, tides, storm surges.
people: human activity, coastal management
atmospheric - climate, weather and climate change.
Processes: Erosion, mass movement, deposition
Outputs: Erosional landforms and depositional landforms
What is a concordant coastline?
Where the folding or arrangement of rocks is parallel to the coast
What is the definition of joints
Vertical cracks - fractures, caused by either contraction as sediments dry out, or by earth movements during uplift
What are some characteristics of sedimentary rock?
▪ Annual recession of 2.5cm
▪ Often porous
define dynamic equilibrium
refers to the maintenance of balance in a natural system, despite being in a constant state of change
What is the littoral zone and what describe the sections.
The littoral zone is an area consisting of 4 sections called the backshore, foreshore, nearshore and offshore and is a dynamic zone of rapid change.
Backshore - not under the influence of waves
Foreshore: intertidal - between low and high tide
nearshore: where the waves break. breakpoint bar
offshore: beyond the influence of waves
