Definition: A set of interrelated parts, including inputs, outputs, and processes.
Energy
Definition: Enables geomorphic processes and takes the form of kinetic, potential, or thermal energy.
Geomorphic
Definition: Relating to the shape of the Earth’s surface.
Sediment Cell
Definition: A stretch of coastline and nearshore area where sediment is largely self-contained.
Physical Factor
Definition: A natural reason that has an effect on processes or landforms.
Tide
Definition: The periodic rise and fall of the sea surface caused by the gravitational pull of the moon.
Lithology
Definition: The physical and chemical composition of rocks.
Rock Structure
Definition: The properties of rock types, such as jointing, bedding, faulting, and permeability.
Ocean Current
Definition: A large scale movement of heat energy and water caused by wind and the earth’s rotation.
Rip Current
Definition: Strong and narrow currents moving in the opposite direction to breaking waves.
Terrestrial
Definition: Relating to land.
Fluvial
Definition: Relating to rivers.
Weathering
Definition: The in-situ (i.e. no movement) breakdown of rocks.
Mass-Movement
Definition: A large-scale movement of material down a slope due to gravity.
Marine
Definition: Relating to the sea.
Aeolian
Definition: Relating to wind.
Longshore Drift
Definition: The zig-zag movement of sediment along a coast caused by waves approaching at an angle.
Deposition
Definition: Dropping or laying down of material.
Beach Nourishment
Definition: Artificially adding sediment to a beach.
Coastal Landscape Systems
Energy and material flow through coastal landscape systems, which are considered open systems.
Inputs
Energy:
- Kinetic from wind and waves.
- Thermal from the sun.
- Gravitational potential.
Sediment: From rivers, cliffs, etc.
Processes
Erosion, transportation, sediment transfer.
Outputs
Erosion, evaporation.
Sediment Cells
A stretch of coast and nearshore area that is considered a closed system.
Key characteristics: 11 large sediment cells in England/Wales often bounded by natural formations like headlands. Sub-cells also exist.
Sources of Coastal Sediment
Terrestrial (from land):
- Fluvial: Sediment is brought downstream by rivers (e.g., the Nile).
- Weathering: Material broken down and later moved by mass movement.
Marine Erosion: Cliffs eroded due to wave action.
Aeolian Deposition: Material transported and deposited by wind.
Longshore Drift: Material transported along a coast due to prevailing wind direction.
Offshore Marine Deposition: Sediments transported from offshore areas by waves and currents.
Human Influences
Beach Nourishment: Sediment deposited artificially on beaches sourced from inland, offshore, or rivers.
Physical Factors Influencing Coastal Landscape Systems
Tides
Definition: Caused by the gravitational pull of the moon.
Types of Tides:
- Spring Tides: Occur when the moon, sun, and Earth are aligned, resulting in the highest tides.
- Neap Tides: Occur when the moon and sun are at right angles to each other.
Geology
Lithology
Definition: The chemical composition and erosion resistance of rocks. For example, clay has weak lithology compared to basalt, which is strong.
Structure
Refers to properties of rocks such as joints, faults, and permeability.
Waves
Characteristics:
- Created by wind friction across oceans, transferring energy in circular motions.
- Wave energy ($P$) is calculated as follows: P=H2T
where H is wave height and T is the time between wave crests. Wave height is the more important factor in this equation.
- Types of Waves:
- Swell Waves: Created in open oceans, travel long distances with long wavelength and periods.
- Storm Waves: Shorter wavelength with greater height and shorter periods.
Breaking Waves
Waves break when the depth is less than 1.3 times the wave height.
Types of Breaking Waves:
- Spilling: Gentle breaking with forward focus of energy.
- Plunging: Downward focus of energy.
- Surging: Waves slide forward but may not break.
Swash and Backwash: Swash is the forward movement of a wave up a beach, while backwash is the return flow due to gravity.
Ocean Currents
Global ocean currents created by Earth’s rotation, moving thermal energy and water.
Warm currents affect western coastlines (e.g., Gulf Stream toward the UK) and modify local climates, affecting weathering.
Winds
Impact on coastal landscapes:
- Higher wind speeds and longer durations create larger waves with more energy.
- Fetch: The distance winds blow waves across an open ocean; it influences wave size and energy.
- Onshore winds drive waves towards the coastline while wind direction influences sediment movement.
Coastal Processes Definitions
Aeolian
Definition: Relating to wind.
Concordant Coastline
Definition: Geology arranged parallel to the coast.
Discordant Coastline
Definition: Geology arranged at right angles to the coast.
Deposition
Definition: The laying down of material as waves lose energy.
Erosion
Definition: The breaking down and removal of rock/sediment.
Fluvial
Definition: Relating to rivers.
Geomorphic Processes
Definition: Processes that alter the Earth's surface shape, including weathering, mass-movement, erosion, transportation, and deposition.
Inter-relationships
Definition: Connections that exist between processes and landforms along a stretch of coast.
Mass-Movement
Definition: Large scale movement of material down a slope due to gravity.
Millennia
Definition: A term denoting thousands of years.
Drift Aligned Coast
Definition: Waves approach at an oblique angle.
Swash Aligned Coast
Definition: Waves break parallel to the coast.
Transportation
Definition: The movement of material.
Weathering
Definition: Gradual breakdown of rock in situ.
Weathering
Types
Physical Weathering:
- Freeze-thaw: Water enters cracks, freezes, expands, and breaks down the rock over time.
- Salt Weathering: Salt residues create crystals that exert pressure as they grow.
- Wetting and Drying: Clay-rich rocks expand when wet and contract when dry, causing cracks.
Biological Weathering: Caused by plant roots and burrowing animals.
Chemical Weathering (Carbonation): Rainwater absorbs CO2 to form carbonic acid, which reacts with carbon-based rocks like chalk and limestone.
- Colder water absorbs more CO2, making carbonation more prevalent in winter.
Mass Movement
Factors influencing mass movement include slope gradient, saturation levels, and vegetation cover.
Types of Mass Movement
Rock Fall: Common in jointed rocks; occurs on slopes over 40 degrees and is more likely on steeper slopes.
Cliff Slump: Rotational movement of material on steep slopes due to saturation.
Soil Creep: A very slow process, approximately 1 cm per year.
Transportation Processes
Types of Transportation
Solution: Invisible load of dissolved minerals.
Suspension: Small particles are carried by water currents.
Saltation: Irregular movement where particles are temporarily picked up and later dropped.
Traction: Large particles are dragged or rolled by water flow.
Erosion Processes
Types of Erosion
Abrasion: Sediment carried by waves scours cliffs and seabeds.
Attrition: Rock particles collide with each other during transport, becoming smaller and more rounded.
Hydraulic Action: Waves trap air and water in cracks, causing pressure release and widening of the cracks. Atlantic waves can exert forces of up to 11,000 kg/m³.
Pounding: The weight of breaking waves exerts pressure, leading to forces of approximately 30 tonnes/m².
Solution: Minerals (e.g., magnesium carbonate) can be dissolved, although the effect is limited due to seawater pH typically ranging from 7-8.
Wave Refraction: Bending of waves due to friction in shallower water, resulting in concentrated erosion in headlands.
Deposition
Causes of Deposition:
- Sediment exceeding the available energy for transport.
- Percolation of water in backwash on beaches.
- Loss of energy due to sheltering in areas like estuaries.
- Flocculation: Clumping of clay particles transported by rivers in saltwater, making them heavier and leading to deposition.
- Contrasting flow directions of river and waves can cause energy loss.
Erosional Landforms
Types
Headlands and Bays:
- Formed from adjacent eroded areas due to varying geological resistance. Width of bays on discordant coasts depends on weaker rock bands. Small bays/coves may appear in weaker sections of concordant coasts.
Cliffs:
- Characterized by undercutting leading to collapse, creating steep profiles. Cliff gradients vary based on rock type and structure, such as bedding orientation.
Shore Platforms:
- Left behind as cliffs retreat; typically sloped at 0-3 degrees, often with accumulated large rocks. Physical and biological weathering occurs at low tide, with erosion being most pronounced at high and low tides.
Geos:
- Narrow, steep-sided inlets formed along weaknesses in cliffs.
Blowholes:
- Form through the collapse of tunnel-like caves or due to erosion.
Caves, Arches, Stacks, and Stumps:
- Commonly found on headlands, formed through concentrated wave energy at defects in coastal geology.
Depositional Landforms
Types
Beaches:
- Primarily composed of sediment from various sources, with sandy beaches exhibiting gentler gradients than shingle beaches.
- Origins of Sediment: 5% from cliff erosion, 5% from offshore, and 90% from rivers. Higher energy waves create flatter beaches that draw sediment offshore.
Spits:
- Narrow beaches extending from land into the water, often formed across bays due to longshore drift. Recurved ends develop due to wave refraction, with sediment deposition creating salt marshes.
On-Shore Bars:
- Result from spits joining land on both ends, forming lagoons of brackish water behind.
Tombolos:
- Result from beaches connecting mainland to islands, formed similarly to onshore bars.
Salt Marshes:
- Develop in low-energy estuarine environments, characterized by vegetation and daily inundation by tides, supporting sediment accumulation.
Coastal Landforms: High Energy Coastline from Saltburn to Flamborough Head
Physical Factors
Geology: Discordant coastline with resistant rocks (chalk, sandstone, limestone) eroding less than 0.1m/year and glacial till with an average erosion of 0.8m/year.
Energy: Dominant waves from N and NW with a fetch of 1500km, with maximum wave heights of 4m. Significant longshore drift from North to South and a 4m tidal range.
Sediment Sources: Limited fluvial sediment due to management of the Esk River; net increase in beach sediment despite variability in seasonal budgets.
Landforms
Cliffs: Vertical sedimentary rocks primarily covered by glacial till—Flamborough cliffs are 20-30m high with gradients up to 40 degrees.
Shore Platforms: Wide at Robin Hood's Bay, some with evidence of being relict features from previous interglacial periods.
Headlands and Bays: Ravenscar (sandstone) and Flamborough (chalk) as prominent headlands, with bays such as Robin Hood’s Bay and Filey (shale and clay).
Other Features: Green Stack's Pinnacle (stack) at Selwick’s Bay and over 50 geos showing north-east alignment due to wave direction; blowholes forming at certain locations.
Beaches: Limited due to sediment supply; Filey and Scarborough are notable well-developed examples.
Coastal Landforms: Low Energy Coastline of the Nile Delta