3- Coastal Landscapes Over Time Flashcards
2 process of sea level change
Eusatic (change in height of sea)
- more/less water in ocean
- warmer climate = thermal expansion
Process of sea level rise due to warming climate
- melting of terrestrial ice = more water in ocean
- warmer climate = thermal expansion = water molecules take up more space
Process of sea level fall due to cooling climate
- more water stored on land as terrestrial ice = freezing of rain water= ocean water evaporates = rain = rain freezes = less water in ocean
- thermal contraction = water molecules take up less space as they vibrate less due to less energy
What is a Ria and how does it form
Flooded river estuary , wide + gentle sloping
1- river erodes forming wide valley + floodplain
2- sea level rise
3- river valley is submerged
How can a Ria change over time
- sheltered inlet = low energy environment = allows deposition of sediment = Ria gets shallower
- erosion at mouth of river = becomes wider
- in low energy environments flocculation may of or at mouth = deposition
- narrow inlet = waves have very little energy
What is a Fjord and how does it form
Glacial U-shaped valley flooded by rising sea
- steep + narrow with deep channel
1- glacier erodes/ carves gorge by the scraping of sediment in glacier over land
2- sea levels rise
3- glacial valley is submerged
How might a fjord change over time
- weathering + marine erosion break down sides of fjord = gentler sloping gradient
- deposition at sheltered end of fjord = shallower + change of beach forming
- erosion at mouth of river (entry to fjord) becomes wider
What is a shingle beach and how does it form
Deposited material rolled onshore as sea levels rise , can appear as a straight bar
1-sediment deposited by rivers, waves etc
2- sea levels rise
3- sediment rolled inland as sea rises
How might a shingle beach change over time
- smaller material/sediment is vulnerable to erosion = sorting of sediment by size as longshore drift transports smaller sediment further down coast
- beach can become steeper due to rising sea level
- larger sediment is pushed up further and is not eroded due to it requiring a lot of energy = larger sediment at back
What is a raised beach and how does it form
Flat area higher than sea level = former wave cut platform
1-erosion of cliff = WCP
2- sea level fall/ regression
3- WCP exposed
How might a raised beach change over time
- colonised by vegetation = hold it together + make more stable
- could be undercut = raised beach falls + eroded away
What are abandoned cliffs + how do they form
-Steep rocky land above present day sea level, often contain other erosion as landforms such as caves or arches
1- steep cliff formed by wave erosion
2- sea level fall/regression
3- cliff left exposed above high tide mark
How might abandoned cliffs change over time
- potential for undercutting + mass movement
- weathering
= a chance for a build up of sediment beneath cliffs
What is a marine terrace + how might it form
A series of flat areas + sloping areas leading up sea = shows the series of steps in landscape as sea levels fall in stages
1- WCP formed
2- sea level fall
3- another WCP formed at that level
4- sea levels fall again
= series of steps/WCPs
How can a raised beach continue to change over time
- vegetation colonies = strengthens or weakens WCP
- weathering + mass movement leading to a more gentle profile
- wave erosion at base
- sea levels rise could affect via marine proscess
2 types of sea level rise
Eustatic = change in water level
Isostatic = change in land level
What is Isostatic depression + rebound
Depression = build up of material on land = weight of material pushes down on crust = allowing sea to rise further inland
Rebound= removal of sediment of land = land “rebounds” up due to less weight/pressure on it = sea levels fall on local scale
How much are sea levels rising a year
3.3 mm
What could happen to sea levels if greenlands ice sheets melted
6m of sea level rise
Give an example of a place experiencing isostatic action
Scotland undergoing isostatic rebound = land rising due to not being compressed by ice
How much lower we’re sea levels in last glacial period - 70,000 years ago
100-150 m
What is the term for retreating sea levels exposing land
Marine regression
How much colder was the last glacial period
5*C lower
Devensian period
How much warming is required for 2m of global sea level rise
1•C
