2B.1B Classifying Coasts
Coasts can be classified by using longer term criteria such as geology and changes of sea level or shorter term processes such as inputs from rivers, waves and tides.
Long Term Criteria
Geology
Geology is all the characteristics of land, including lithology (rock type) and structure (arrangement of rock units).
It can be used to classify coasts as rocky, sandy or estaurine.
Or, concordant and discordant.
Sea Level Change
Sea level change can be used to classify coasts as emergent or submergent.
This can be caused by:
Geology is all the characteristics of land, including lithology (rock type) and structure (arrangement of rock units).
It can be used to classify coasts as rocky, sandy or estaurine.
Or, concordant and discordant.
Sea Level Change
Sea level change can be used to classify coasts as emergent or submergent.
This can be caused by:
- Tectonic processes can lift sections of land up, causing local sea fall, or lead sections of land to subside, causing local sea rise.
- Climate change causes sea levels to rise and fall in a 100,000 year cycle due to the change in the Earth's orbit shape.
- sea levels fall for 90,000 years during glacials as ice sheets expand and rise for 10,000 during interglacials
- sea levels rise even more when the Earth emerges from an ice age and all surface ice melts
Short Term Criteria
Energy Inputs
Coasts receive energy inputs from waves (main input), tides (ebb and flow over a 12.5 hour cycle), currents. rivers, atmospheric processes, gravity and tectonics.
Used to classify coasts as high energy and low energy.
Sediment Inputs
Coasts receive sediment inputs from waves and wind (vary constantly with weather), tides (ebb and flow over 12 1/2 hour cycle), currents, mass movement and tectonic processes.
Sediment is added to a coastline through deposition and removed by erosion.
Where erosion > deposition there is a net loss of sediment and the coastline retreats -- an eroding coastline.
Where deposition > erosion there is a net gain of sediment and the coastline advances -- an outbuilding coastline.
Advancing/Retreating
Coastlines are classified as advancing or retreating due to long-term processes (emergent/submergent) and short term (outbuilding/eroding).
Coasts receive energy inputs from waves (main input), tides (ebb and flow over a 12.5 hour cycle), currents. rivers, atmospheric processes, gravity and tectonics.
Used to classify coasts as high energy and low energy.
Sediment Inputs
Coasts receive sediment inputs from waves and wind (vary constantly with weather), tides (ebb and flow over 12 1/2 hour cycle), currents, mass movement and tectonic processes.
Sediment is added to a coastline through deposition and removed by erosion.
Where erosion > deposition there is a net loss of sediment and the coastline retreats -- an eroding coastline.
Where deposition > erosion there is a net gain of sediment and the coastline advances -- an outbuilding coastline.
Advancing/Retreating
Coastlines are classified as advancing or retreating due to long-term processes (emergent/submergent) and short term (outbuilding/eroding).
Random Stuff!
- Rock formation can take millions of years.