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
Name of last glacial period
Devensian period
70,000 years ago
Name of current interglacial period called
Holocene period
main reason for changing sea levels
Milankovitch cycles
- However the effect of human activity is accelerating the rise of temps and sea levels beyond natural
In the previous Inter-glacial (130,000 years ago) how much higher were sea levels and how much warmer was it
20m higher
3.C warmer
