emergent and submergent features Flashcards
what are submergent features
when sea levels rise and flood areas not previously underwater
examples of submergent features
rias
fjords
dalmation coast
what is ria
drowned river valley
ria characteristics
dendritic drainage pattern
wide deep mouth
narrower and shallower inland
U shape sides
submergent
ria formation
1) rivers erode to sea level
2) fall in sea level due to more ice locked up on land (eustatic)
3) so river erodes more vertically in lower course deepening river bed
4) when sea level rises again it floods the river causing ria
ria example
kingsbury estuary - Devon
6 miles long
main channel 1 mile wide at salcome
what is a fjord
drowned glacial valley
fjord characteristics
- steep U shaped valley
- relatively straight and narrow
- shallow mouth due to the ‘threshold’ formed by deposition glacial material
- deep further inland
fjord formation
1) Need pre existing v shaped river valley where the river flowing from mountains to sea.
2) ice age occurs, so ice forms at top mountain and moves down the river valley due to continuous formation at top.
3)As ice mass grows it moves down the river valley.
This erodes the river valley creating a U shaped valley.
4) Process continues and gets wider
ice melts leaving U shaped valley
fjord example
sogne - norway
204km long
what is dalmation coast
series of long and narrow islands which run parallel to the coast
dalmation coast characteristics
concordant coastline produced by folds parallel to the coast
long and narrow islands which run parallel to the coast
islands separated by narrow sea channels called sounds
dalmation coast formation
1) Tectonic forces from the collision of African and Eurasian plates compressed Limestone 50 million years ago
2) creating folded ridges and down folded valleys parallel to the coast.
3) The Sea levels rose after the last glacial period which meant that the sea overtopped the up folded ridges and the sea flooded the down folded valleys (Eustatic change)
4) This produces lines of narrow islands parallel to the coast. separated by narrow sea channels parallel to the coast (sounds)
dalmation coast facts
croatia
adriatic sea
70 islands and 500 islets
520km from NW to SE
main rock = limestone
what are emergent features
landforms created either by a fall in sea level or uplift of the land resulting in the sea level being at a lower level relative to the land than before
examples of emergent features
raised beach
marine platform
what is a raised beach
former wave cut platforms and their beaches raised above sea level
characteristics raised beach
raised above high tide level
relic caves and cliffs
can be vegetated
raised beach formation
1) relatively flat surface which has been lifted out of reach of the water
2) This can occur due to a fall in sea level
or
tectonic uplifts, resulting in defined terracing
3) As glaciers melted, the land recovers from the weight of the ice and begins to rise.
depending on amount and when it melted results in several raised beaches forming
Emergent feature + isostatic
raised beach example
isle of arran - scotland
raised beach 5m above sea level
has 3 different terraces
what is marine platform
relatively flat surface of marine origin lifted out of water
characteristic marine platform
steeper ascending slope on one side and a steeper descending slope on the other side
relatively flat
marine platform formation
1) due to the uplift of the land and eustatic natural rise and fall of sea level
2) When shoreline updrift occurs, a wave-cut platform will become elevated above sea-level
1they will dry and become marine terraces, thus becoming land.
marine platform example
Taranaki Region, New Zealand
oldest terraces reach 20km inland
formed over 700,000 years from land uplift and sea level fluctuations
