EQ1 Coasts Flashcards
What is the littoral zone
Area of coast where land is subject to wave action
Subsections of littoral zone
Backshore- only affected by high tide
Foreshore- where most wave processes occur
Offshore- open shore
Concordant coastline and features
Where rock type banding is parallel to the sea
Creates coves
Discordant coastline and features
Rock type banding is 90° to the sea
Creates bays and headlands
What is a Dalmatian coastline
Where geology creates valleys parallel to the coast so when sea level rises, elongated islands remain offshore
What is a half coastline
Depositional landforms where spits form across a bay and creates a lagoon behind
What are strata
Horizontal layers of rock
What is bedding plane
Natural breaks between strata caused by gaps in time during periods of rock formation
What is a dip
The angle at which strata lie
What are folds
Pressure during tectonic activity which es rock to buckle or crumple
What are faults
Formed when stress or pressure exerted on a rock exceeds its internal strength, causing a fracture
Faults slip or move along fault planes
What is a cliff profile
The height and angle of a cliff face plus its features
Features include wave cut notches or changes in slope angle
Igneous rock formation + features
Cooled erupted magma
Interlocking crystalline structure with few faults or joints
Few weaknesses for erosion to exploit
Very now annual recession (1mm/year)
Metamorphic rock formation + features
Formed under high heat + pressure
Crystalline - foliation means all crystals orientated in same direction creating weakness
Many folds, joints and cracks creating weakness
Slow rate of recession (1mm/year)
Sedimentary rock formation and features
Sediment compacted
Clastre, weaker than crystalline
Fast rate of erosion (1mm - 1m/year)
What is weathering
Sub aerial process
Chemical, biological, mechanical breakdown of rocks into smaller pieces and minerals
What is mass movement
Subaerial process
Landslides, slumps and rock falls which move material downslope under the influence of gravity
What is a sediment cell
Area of coast often hemmed in by physical barriers
Contains sediment budget in dynamic equilibrium
It contains sources and stores which become sinks when permanent
How is a stump formed?
Water rises through joint forming a blowhole
Erosion widens weakness, forming cave
Waves out through headland to form arch until roof of arch becomes too heavy and collapses to form a stack
The stark is undercut by subaerial processes and collapses, leaving a stump
How are Wave cut notch + platforms formed
Erosion concentrated around high tide line, creates wave cut notch
Rock above notch becomes more unstable as notch deepens until it collapses, leaving wave cut platform.
What does dynamic coastline mean
The coastline is constantly changing due to physical processes, human processes and natural hazards
What are some human processes which can impact the coastline
Harbours, marinas
Tourism
Fishing
Undersea oil extraction
HEP
Residential areas
What are some examples of physical processes which can impact coastlines
Terrestrial - weathering
Marine- wave action erosion
What makes coasts such dynamic environments
Affected by both marine and terrestrial processes
Experience extreme events which change their landscape
Human development is varied and is constantly expanding which puts different pressures on the system
What are some examples natural hazards which can impact coastlines
Tsunami
Hurricane
Storm surge
What is an open system
Energy and matter can come into the system as well as leave the system
What are some coastal inputs of energy and matter
Energy - kinetic energy from waves and wind , thermal energy from sun, potential energy from material on cliffs and slopes
Material - sediment from processes of weathering, mass movement, erosion and deposition
What is a rocky/ cliff coastline features
Cliffs vary in height up to hundreds of metres
Dramatic distinction between land and sea
What are some features of a coastal plains Coastline
Land which gradually slopes towards the sea across deposited sediment
Sand dunes, mud flats
Blurred division between land and the sea
What are characteristics of waves in a low energy coast
Constructive, less powerful
Calmer conditions
Short fetches
What are examples of processes occurring in a low energy coastline
Deposition and transport
Sediments from rivers, longshore drift
Nearshore currents
Name some landforms which form in a low energy coast
Depositional landforms
Beaches
Spits and bars
Salt marshes
Sane dunes
Mudflats
What are some examples of low energy coasts
Mediterranean Sea coasts
East Anglian coast
What are characteristics of waves in a high energy coast
More powerful destructive waves
Storm conditions
Long fetches
What are some examples of processes which occur in a high energy coastline
Erosion
Transport of sediment from eroded land
Mass movement
Weathering
Offshore currents
What are some examples of landforms which occur in a high energy coastline
Erosional
Cliffs
Wavecut okatforms
Arch cave stack stump formations
What are some examples of high energy coastlines
Atlantic coast of Norway and Scotland
Pacific coasts of Alaska and Canada
What is the morphology of a coast determined by
Lithology or physical characteristics of rock
Relief and slope of cliff profiles
Rock type
Permeability of rock
Rocks resistance to erosion
What is coastal morphology
The shape and form of coastal landforms and their features
How does geology influence coastal development
Location of micro features (caves, wave cut notches) within a coastline are controlled by the location of faults and strata with a high density of joints and fissures
Why does folding of rock occur
Crustal compression
Horizontal strata squeezed into anticlines (A shaped) and sync lines (U shapes)
Accompanied by joints and fissures
What kind of cliff profile do uniform horizontal strata produce
Steep cliffs
What can happen when a cliff profile has rocks dipping seaward with vertical joints?
Joints opened by weathering and pressure releases large slabs
Can cause mass movement
What is the most stable cliff profile
Rocks dipping inland - causes reduced rock fall
How can rocks dipping inland become unstable
When there are well developed joints at the right angle- can form slide planes and cause mass movement
What is coastal recession
The movement of cliffs inland
What is resistance of a cliff most influenced by.
Its weakest rock type
What is the difference between intrusive and extrusive igneous rocks
Intrusive - slow cooling of magma
Extrusive- rapid cooling of la a
Examples of igneous rock
Granite (intrusive) , basalt (extrusive)
What are the different types of sedimentary rock
Clastic - compaction of broken rocks
Chemical - compaction of dissolved minerals
Organic - compaction of organic materials
What are some examples of the different types of sedimentary rock
Clastic- sandstone
Chemical- rock salt
Organic- coal, limestone
What are the different types of metamorphic rock
Foliated ( distinguishable by layers)
Non foliated ( indistinguishable layers)
What are some examples of the different types of metamorphic rock
Foliated - skate
Non Foliated - marble
How does vegetation stabilise sandy coastlines
Roots bind sediment together making them harder to erode
Sheltering from water - sediment not directly exposed to moving water
Sheltering from wind- reduce wind speed with friction
What are the two types of vegetation which grow at coastlines
Halophytes - can tolerate salt water
Xerophytes - can tolerate very dry conditions eg found in sand dunes
What is succession
The changing structure of a plant community over time as an area of initially bare sediment is colonised by plants
What are the different names for a sand dune and salt marsh climax community
Sand dune - psammosere
Salt marsh - halosere
How are salt marshes created
Bare mud desposited on estuaries is exposed to sea at low tide and submerged at high tide
Ideal at estuaries because it is sheltered and there is an extra sediment source from the river
