Coastal Landscapes Notes
Coasts as a system
A coastal landscape is an example of an open system:
-It has INPUTS (e.g. Energy from waves, sediment from other coastlines)
-It has THROUGHPUTS/STORES (e.g. Longshore drift, Aeolian Transportation)
-It has OUTPUTS (e.g. Sediment eroded from coastline transported away)
However, it could be argued that the coastal system as whole is a closed system
Sediment Cells are an example of a closed system
-Areas of a coastline where the sediment is self-contained through longshore drift and landforms
limiting the sediment's movement
Parts of a coastline (HAVE TO LEARN)
Influences on Coastal Landscapes
1) WIND (Aeolian)- Frictional drag can increase energy for coastal erosion and sediment transport
- Higher windspeed, longer fetch -> larger the waves and more energy
- Can also carry out erosion, transportation and deposition itself
2) WAVES -Location of the formation of waves can affect wavelength, height and period- Swell
Waves formed in open oceans will be larger than locally generated storm waves
- Constructive waves (big swash, small backwash) tends to retain its energy due to uninterrupted
swash movements, destructive waves tend to lose energy due to the frictional effects of meeting the
returning backwash
, 3) TIDES- The periodic rise and fall of the sea surface produced by the gravitational pull of the moon
-SPRING TIDES- highest tides where Moon, Sun and Earth are all aligned
-NEAP TIDES- lowest range when moon and Sun are perpendicular
-Compensatory bulge on opposite side of Earth
-Tidal range influences where wave action occurs- if tidal range is low, energy concentrated to
smaller area and more wave influence
4) GEOLOGY- LITHOLOGY (chemical composition of rocks)- Rock types with a weak lithology, such as clay,
not as resistant to erosion as rocks such as basalt as they have stronger bonds between particles
-STRUCTURE- An important influence on the planform of coasts at a regional scale
-Concordant coastlines/discordant coastlines (perp)
- Jointing, bedding and faulting in rocks can be exploited by wave action
-Angle of dip of rocks can have significant effect on cliff profiles
-Horizontally and landward dipping=steep, vertical cliff profiles
- Seaward dipping tend to follow dip of bedding planes
5) CURRENTS- Rip currents (cellular circulation generated by differing wave heights parallel to shore) is a
significant transporter of coastal sediments- modify shore profile by creating cusps, channelling flow
through a narrow neck
-Ocean currents transfer heat energy from low latitudes to the poles- significant as it affects
air temperature and sub-aerial processes
Example of a Negative Feedback Mechanism
1) A storm may disrupt an equilibrium, bring high energy waves onshore, removing sediment, lowering the
beach and transporting the material away to be deposited as an offshore bar
2) Offshore bar causes waves to break, dissipating the energy- waves will therefore have less energy and
will deposit, leading to the beach's height to rise
Sediment Sources
1) Terrestrial- from Rivers, Cliffs, and Land, usually as a result of erosion
2) Offshore- Transported by longshore drift, tides, currents- from sand bars and Aeolian material
3) Human Sources, e.g. through beach nourishment
4) Changes to the sediment budget
Geomorphic Processes
1) WEATHERING- The breakdown of rock or material in situe
Three types:
-Physical or Mechanical- when rock is broken down into smaller fragments of rock
-allows further weathering to take place due to larger SA
-E.g. Freeze-Thaw and Onion-Skin
-Chemical Weathering -When rock is decayed
-Involves chemical reactions between moisture and minerals within rocks
-Produce weak residues of different material- easily transported away
-Rate of most chemical reactions increases with temperature
-Van't-Hoff's Law- 10 degree increase leads to 2.5 increase in rate of
weathering
-E.g. Carbonation (better in cooler temperatures) and Oxidation
Coasts as a system
A coastal landscape is an example of an open system:
-It has INPUTS (e.g. Energy from waves, sediment from other coastlines)
-It has THROUGHPUTS/STORES (e.g. Longshore drift, Aeolian Transportation)
-It has OUTPUTS (e.g. Sediment eroded from coastline transported away)
However, it could be argued that the coastal system as whole is a closed system
Sediment Cells are an example of a closed system
-Areas of a coastline where the sediment is self-contained through longshore drift and landforms
limiting the sediment's movement
Parts of a coastline (HAVE TO LEARN)
Influences on Coastal Landscapes
1) WIND (Aeolian)- Frictional drag can increase energy for coastal erosion and sediment transport
- Higher windspeed, longer fetch -> larger the waves and more energy
- Can also carry out erosion, transportation and deposition itself
2) WAVES -Location of the formation of waves can affect wavelength, height and period- Swell
Waves formed in open oceans will be larger than locally generated storm waves
- Constructive waves (big swash, small backwash) tends to retain its energy due to uninterrupted
swash movements, destructive waves tend to lose energy due to the frictional effects of meeting the
returning backwash
, 3) TIDES- The periodic rise and fall of the sea surface produced by the gravitational pull of the moon
-SPRING TIDES- highest tides where Moon, Sun and Earth are all aligned
-NEAP TIDES- lowest range when moon and Sun are perpendicular
-Compensatory bulge on opposite side of Earth
-Tidal range influences where wave action occurs- if tidal range is low, energy concentrated to
smaller area and more wave influence
4) GEOLOGY- LITHOLOGY (chemical composition of rocks)- Rock types with a weak lithology, such as clay,
not as resistant to erosion as rocks such as basalt as they have stronger bonds between particles
-STRUCTURE- An important influence on the planform of coasts at a regional scale
-Concordant coastlines/discordant coastlines (perp)
- Jointing, bedding and faulting in rocks can be exploited by wave action
-Angle of dip of rocks can have significant effect on cliff profiles
-Horizontally and landward dipping=steep, vertical cliff profiles
- Seaward dipping tend to follow dip of bedding planes
5) CURRENTS- Rip currents (cellular circulation generated by differing wave heights parallel to shore) is a
significant transporter of coastal sediments- modify shore profile by creating cusps, channelling flow
through a narrow neck
-Ocean currents transfer heat energy from low latitudes to the poles- significant as it affects
air temperature and sub-aerial processes
Example of a Negative Feedback Mechanism
1) A storm may disrupt an equilibrium, bring high energy waves onshore, removing sediment, lowering the
beach and transporting the material away to be deposited as an offshore bar
2) Offshore bar causes waves to break, dissipating the energy- waves will therefore have less energy and
will deposit, leading to the beach's height to rise
Sediment Sources
1) Terrestrial- from Rivers, Cliffs, and Land, usually as a result of erosion
2) Offshore- Transported by longshore drift, tides, currents- from sand bars and Aeolian material
3) Human Sources, e.g. through beach nourishment
4) Changes to the sediment budget
Geomorphic Processes
1) WEATHERING- The breakdown of rock or material in situe
Three types:
-Physical or Mechanical- when rock is broken down into smaller fragments of rock
-allows further weathering to take place due to larger SA
-E.g. Freeze-Thaw and Onion-Skin
-Chemical Weathering -When rock is decayed
-Involves chemical reactions between moisture and minerals within rocks
-Produce weak residues of different material- easily transported away
-Rate of most chemical reactions increases with temperature
-Van't-Hoff's Law- 10 degree increase leads to 2.5 increase in rate of
weathering
-E.g. Carbonation (better in cooler temperatures) and Oxidation
