Emergent and Submergent coasts Flashcards
what are Rias
they are submerged river valleys, formed as sea level rises, however the top part of the river course may stay exposed
what are Fjords
they are submerged glacial valleys. they have step, almost cliff like valley’s sides and the water is uniformly deep (often reaching over 1000 deep)
for example the Sogne Fjord in Norway is nearly 200km long
what are shingle beaches
when sea level falls as the volume of land based ice grows, large areas of ‘new’ land emerge from the sea
what happens in a transgression
- sea level rises
- eustatic change
- leading to existing landforms being submerged
what happens in regression
- rise in land level
- isostatic change
- emergent landforms occur
when as the world sea level at the lowest point
16000
what has happened to northern Scotland
has sprung up, due to the weight and pressure that the ice sheets were exerting on them being realeased
what has happen to the south of England
relative drop in sea level (key to remember that over 18,000 years ago you called walk across the English channel to France
how often, do we experience a solar maximum
every 11 years or so
what are the 3 emergent coastal features
- raised beach - used to be a normal beach
- marine terrace - similar to raised beaches much higher up, could of been a short platform before sea level rose
- a relict cliff a cliff however know it is far more stable as erosion only occurs from weathering and mass movement
what process, could modify a relic cliff
- weathering
- mass movement
what process, could modify a marine terrace
- will no longer experience wave erosion
- could experience weathering
- possible mass movement process may effect it.
what process, could modify a raised beach
- becomes covered in vegetation
- weathering may effect it
- mass movement process may effect it
name the 3 submergent coastal features
- rias
- fjords
- shingle beaches
state 3 reasons why rias form
- tributaries fill with sediment causing some of the water to overspill
- costal process, like deposition and erosion
- current eustatic rise, continues to flood them
state 3 reasons why shingle beaches form
- due to large quantities of sediment being deposited by from glaciers that melted in the Flandrian transgression
- coastal process, have pushed sediment onto the coastline
- eustatic rise in sea level post glaciation, carries sediment on shore, causing these large shingle beaches
state 3 reasons why fjords form
- large glacial valleys become flooded, when the glaciers melted at the end of the glacial periods
- weathering due to current eustatic change
- hanging valleys join fjords at right angle and pre existing spurs create by action of river become truncated
what is eustatic change (sea)
a global change in sea level resulting from an actual fall or rise in the level of the sea
what is a isostatic change (land)
local changes in sea level resulting from the land rising or falling relative to the sea
emergent coastline
a decrease in sea level
submergent coastline
a increase in sea level
what is a marine terrace
similar to a raised beach it could of been a shore platform, before we saw a decrease in sea level
describe the global eustatic changes in sea level
- shows sea level change, over last 20,000 years
- 18,000 years ago we had the world lowest sea level.
- 8000 years ago, the sea level started to rise slowly
- melting of ice, caused rapid sediment build up, forming beaches, and other depositional landforms
describe the isostatic changes around the UK
- northern Scotland, has sprung up, due to being released from the pressure that the ice sheets had, that caused it to lower
- relative drop in sea level
- 18,000 years ago, one could walk to France.
how does volcanic activity, effect emergent and submergent coasts
changes in the composition of the atmosphere due to major volcanic eruptions, which reduce incident solar radiation
what is a relict cliff
a cliff, which is no more stable, as erosion only occurs on it via the process of weathering and mass movement
