Coasts (Definitions) Flashcards
What is a coast?
The interface between land and sea, can be viewed as a system, with inputs, processes and outputs.
What are the 4 inputs for a coastal system?
Wave energy
Geological structure
Sub-aerial activity
Human activity
What is the fetch of a wave?
The distance over which the wind blows in a constant direction across the surface of the water
What are the 4 processes at a coastal system?
Wave erosion
Mass movement
Hard/soft engineering
Transport
What are the 2 outputs at a coastal system?
- Landforms of erosion
- Landforms of deposition
The 7 processes of coastal erosion:
Abrasion - Waves throw loose material at cliffs
Attrition - Movement sandpapers rocks into smoother and rounded rocks
Solution - Carbonic acid in sea water reacts, and spray corrodes rocks, so they disintegrate
Biological activity - Secretions from algae attack rocks, or some molluscs can bore holes in them
Wave pounding - Wave impact can loosen cliff face rock.
Hydraulic pressure -Waves enter tiny crevice/crack and air is trapped
Sub aerial weathering - Rain leading to saturation of cliff material and the failure of cliff by mass movement
What determines the amount of energy waves have?
Higher wind speeds impart more energy to the waters surface, creating larger and more powerful waves
A longer fetch allows the wind to transfer more energy to the water, resulting in larger waves
What is meant by wave pounding?
The forceful impact of large and powerful waves on a cliff face or coastal structure, pounding or battering effect is pronounced during storms or periods of high winds, with intensified waves.
What are two examples of mass movement?
Landslides involve the rapid downslope movement of rock, soil, and debris along a defined surface, triggered by many diff factors or activities that disturb the stability of a slope
Mudflows are fast-moving mixtures of water, mud, rocks, and debris that flow downslope. They are similar to landslides but involve a higher proportion of water, giving them a fluid-like consistency.
Sub aerial activity triggers this movement when soils are more saturated.
What do all rocks have and why is this important?
Minerals, are fundamental to the composition, classification, and understanding of rocks
What does lithification mean?
The process by which loose sediments are transformed into solid rock, critical in formation of sedimentary rocks
What happens to waves in bays?
The behaviour of waves in bays is influenced by the bay’s specific characteristics, including its shape, depth, and the presence of coastal features
What is threatening the Holderness Coast?
Rapid coastal erosion due to soft geological formation, lack of coastal defences, high erosion rate due to strong waves from the north sea, and sea level rise.
What are the three major inputs influencing cliff formation?
Geological structure - Different types of rocks have varying resistance to weathering and erosion.
Folding and faulting -As a result of earth movements all rocks exhibit some degree of folding which can become weaknesses, creates lines of weakness which can be exploited.
Coastal morphology - On an indented coastline, headland sand the offshore topography concentrate wave attack on the headland by the process of wave refraction.
Abandon the line
the strategic withdrawal of human occupation in areas of high risk
Accretion
the accumulation of marine sediments
Advance the line
Active intervention to produce a defence line that is seaward of the existing line
Arch
A raised area when two caves erode back to back on a headland
e.g. Durdle Door
Backwash
movement of water back towards the sea after a wave has been broken
Bar
Coarse grained deposit of sediment extending across the mouth of the bay
Berm
Low hill of sand or gravel that forms at the upper limit of the swash
Beach nourishment
sand and shingle brought from elsewhere are added to beaches to maintain depth to protect from erosion in a natural way
Char
An island formed from silt deposit in a delta, the land is about at sea level and is very fertile, however easily washed away
Constructive waves
Low frequency 6-8 per minute waves with elliptical water motion, powerful swash and weak backwash
Concordant geology
The alignment of bands of alternate geology that run parallel to the coastline
Corrasion
Erosion by friction in load of contact with banks and bed