submergent and emergent coastlines

Question 1

what is a submergent coastline?

Answer 1

coastline formed by a rising sea level (marine transgression)

Question 2

what are the three examples of submergent coastlines?

Answer 2

Fjords, Rias, and dalmation coastlines.

Question 3

what is a Fjord?

Answer 3

Drowned U shaped glacial valley

Question 4

how do Fjords form?

Answer 4

1) During a colder glacial stage the input of snow is larger than the output via melting or sublimation
2) the snows builds up and becomes compressed ice, eventually growing into a glacier
3) the glacier flows downslope under gravity (basal slippage)
4) as galcier moves it grinds subglacial sediment into the rock below it. this intense abrasion causes vertical erosion.
5) continous erosion from the galcier creates a U shaped valley
6) warmer interglacial stage causes glacier to melt and leave behind the U shaped valley
7) warmer conditions, thermal expansion of water floods the valley, forming a Fjord
8) shallower water at the entrance to the Fjord as snout of glacier was less able to move/erode (known as Threshold)

Question 5

what is the example of a Fjord and what are its dimensions?

Answer 5

SognefJorden, Norway
195 km long, 1300m deep
it is symetrical

Question 6

how much more erosive is ice than water

Answer 6

10x more erosive

Question 7

what is a Ria?

Answer 7

a drowned river valley

Question 8

what shape is a Ria?

Answer 8

dendritic

Question 9

how does a Ria form?

Answer 9

1) water moves faster around outside of a meander bend, this causes lateral erosion through abrasion and h. action (etc) this will attack valley sides and push back bluff lines. this will eventually create a wide valley.
2) when heavy rain, river floods load of river deposited across valley to form a layer of alluvium, creating a flat floodplain.
3) climate change - glacio eustatic sea level rise. rising water floods the river valley. flocculation forms mudflats which are visible at low tide

Question 10

what is our example of a Ria and what are its dimensions?

Answer 10

Kingsbridge Estury , South Devon
7km long
typically less than 10m deep
it is asymetrical

Question 11

what is a Dalmation coastline?

Answer 11

A series of elongated islands that sit parallel to the coastline. They are the result of sea level rise.

Question 12

how are Dalmation coastlines formed?

Answer 12

1) concordant coastline where alternating bands of relatively harder and softer rock types run parrallel to the coastline.
2) differential erosion has caused soft rock to become valleys and hard rock to become highlands. this leaves a sequence of parralel valleys and mountians.
3) global warming has led to glacio-eustatic sea level rise and the thermal expansion of water. this eustatic sea level rise has caused a marine transgression. the river valleys have flooded and left highland as islands.

Question 13

what is an example of a Dalmation coastline?

Answer 13

Croatian Coastline.

Question 14

what is an emergent coastline?

Answer 14

when the sea level falls or the land rises and new land is exposed (marine regression)

Question 15

what is isostatic rebound?

Answer 15

when ground rises up due to the dissapearing of depressing glacial ice.

Question 16

what are raised beaches?

Answer 16

a deposit of former beach material including sea shells which can be found further inland of the present day beach at a higher relief

Question 17

what is an example of a raised beach

Answer 17

Cock of Arran. lower beach at 8m and one at 30m above sea level

Question 18

how do raised beaches form?

Answer 18

sediment e.g sea shells are deposited and then isostatic rebound lifts the beach up. the origional coastline has been emerged

Question 19

relict cliffs

Answer 19

an old cliff found further inland at a higher relief, displaying features such as caves, arches and stacks

Question 20

how are relict cliffs formed?

Answer 20

abrasion and hydralic action occur at a high energy coastline and erode a sea cave. isostatic rebound has shifted the caves up to a higher relief

Question 21

what is an example of a relict cliff?

Answer 21

kings cave in arran, consists of several large caves, approximately 10m high and 15m wide

Question 22

what is a marine platform?

Answer 22

they are a sequence of terraces that slope towards the sea.

Question 23

how does a marine platform form?

Answer 23

end of devensian period, sea levels rose due to glaciers melting which produced a new cliff higher up. Then isostatic rebound occurs due to the regression of the depressing ice, so a new cliff forms at the bottom. this creates a sequence of terraces.

Question 24

what are some of the effects of climate change?

Answer 24

many villages lost to the sea since the domesday book (1086)
10,000 years ago England was joined to mainland europe
75% of the scottish coastline unaffected due to isostatic rebound

Question 25

explain the difference between eustatic, isostatic and tectonic sea level change

Answer 25

Eustatic - rising of sea levels due to heating of oceans, it is global.
isostatic - slower than eustatic caused by melting of depressing ice, it is regional
tectonic - volcanic activity can cause land to rise above the sea, can be the fastest. it is also gobal.