Coasts KQ 3 Flashcards
What could cause a change in global temperature?
- variations in the earths orbit around the sun
- variations in the amount of energy produced buy the sun
-changes in the composition of the earths atmosphere due to major volcanic eruptions
-variations in the tilt of the earths axis
if there is a fall in global temperature how will precipitation be affected ?
more precipitation will fall as snow
if there is a fall in global temperature what will there be lower rates of ?
evaporation , condensation and then precipiatation
if there is a fall in global temperature what will more water be stored as ?
snow and ice (in glaciers and ice sheets )
if there is a fall in global temperatures where will less water be stored in ?
oceans
what is thermal contraction ?
as temps fall , water molecules contract leading to an increased density and reduced volume
what are eustatic changes ?
changes in the volume of water in the global ocean store
when was the tyrrhenian glacial period ?
130 000years ago
how high was the sea level 130 000 years ago ?
20m
when was the riss glacial period ?
108 000 years ago
how low was sea level 108 000 years ago ?
-85m
what period is the flandrian trangsression ?
25,000 years ago to now
(sea l;evel rising to present day )
names some features on an emergent coastline ?
abandoned cliffs
active beach
marine terrace
raised beach
abandoned waterfalls
what is falling sea level ?
during glacial periods the ocean height is reduced because ocean water is stored as ice upon the land surface
what is a raised beach ?
a deposit of sand which is now above sea level
what is a marine terrace ?
a rock terrace where a wave cut platform has been left inland by falling sea levels (or uplift of the land )
what is an emergent landform ?
found inland some distance from the modern coastline as a result of a fall in sea level
what is the plan view of a ria ?
wide and branching plan view
what is the long profile of a ria ?
gentle gradi8ent and the depth is similar all the way along it
what is the cross section of a ria ?
shallow cross section
slightly deeper in the middle
what are rias useful for >?
ideal for harbours and mariners because it is sheltered
when did rias form ?
during the post glacial sea level rise of the flandrian transgression
what is a ria ?
A river valley that’s been flooded by the eustatic rise in sea level, usually where a river meets the ocean📍
what are valley sides like of a ria ?
gently sloping
been formed by mass movement and weathering
what is an example of a fjord in new Zealand?
Milford sound , new zealand
what are fjords used for >?
transport
natural sheltered habour
what is a fjord ?
submerged glacial valley
what is the cross section of a fjord like ?
steep valley sides
water = uniformly deep
U Shaped
sometime deep as 1000 m
deeper than a ria
what is the long profile of a fjord like ?
straighter long profile
shallower section at the end known as the threshold
extra bit of rock at the end
how long is the sogne fjord in Norway ?
200km long
How was a fjord formed ?
interlocking spurs were removed as a u shaped valley was carved out by the glacier which formerly occupied the valley
what is the plan view of a fjord like ?
straighter plan form than a ria
how does a ria form ?
the floodplain is completely drowned and only the middle and upper parts are exposed
what are the processes involved in the formation of a ria ?
formed by fluvial erosion
weathering and mass movement shape the valley sides
underlain by fluvial material deposited during the Flandrian transgression
What processes are involved in the formation of a fjord ?
glacial erosion (abrasion and plunging)
freeze thaw weathering
high marine erosion rates
what is Chesil beach ?
a bar of shingle that joins portland bill to the mainland
how was Chesil beach formed ?
rising sea levels pushed pebbles in a north east direction to create Chesil beach
what may shingle beaches also form ?
may form tombolos and bars
Is falling global temperatures emergent or submergent ?
emergent
is rising global temperatures submergent or emergent ?
submergent
What will rising sea levels lead to ?
Accelerated erosion of cliffs and beaches
Flooding of urban areas
Salinisation of agricultural land
Salinisation of freshwater sources
Widespread destruction of habitats
What are some examples of responses to rising sea level ?
Sea walls
Grounds
Artificial raising of land behind walls
Retreat - abandon land to sea
Upstream draining of dammed lakes
What does peri glacial mean ?
When it was really cold (just after a glacial period)
What does post glacial mean ?
Present day temp
What is an isostatic change ?
Due to rising or sinking of the earths crust caused by either tectonic movement or removal or addition of a great weight (e.g. ice sheeet)
What is post glacial rebound ?
The rise of a land mass after the removal of the huge weight of ice sheets during g the last glacial period , which caused isostatic depression
Are isostatic changes localised or global ?
Localised
Are eustatic changes localised or global ?
Global
What are the peri glacial modifications of emergent landforms ?
Frost weathering causing rock fall from the cliff face
Cryoturbation (frost churning) has disrupted the layers of the permafrost
Layers of debris fo=room frost shattering
What are the post glacial modifications to emergent landforms ?
Development of vegetation cover on some surfaces
More chemical weathering of the limestone by carbonation
Biological weathering by increasing numbers of limpets
What do limpets do ?
Provide a living substrate one which micro-habitats of algae and barnacles can survive
What are the futur modifications of emergent landforms ?
Sea level rise could mean increases action wave processes
How much is sea level rising each year ?
0.6mm
What does not directly affect sea level rise and why ?
Melting sea ice
Already si placing water
What is the upper estimate of sea level rise by 2100 /
0.98mm
Scandavia and Scotland dare rising relative sea level because of which process ?
Isostatic rebound
How and why sea level changed to flood The Valley to create a fjord ?
Thermal expansion - water molecules increase
Flandrian transgression
Glacial ice caps melt which creases sea level
What happened 20,000 years ago in terms of isostatic sea level change ?
Huge ice sheet covered NW Scotland
This huge weight pressed the NW section of the plate down in to the mantle and SE England rose
what is happening present day in terms of isostatic sea level change ?
Ice sheet has melted
The weight has been removed and the NW of Scotland is sprinting back , but the SE is sinking
What is there in the NW of Scotland ?
Is still rebounding
Emergent landforms
What is there is SE England ?
Still sinking
So flooding
Submerge the landforms
What will a 1 degree fall in mean global temp result in ?
Sea level to fall by 2m
What will a 1 degree rise in the mean global temp cause ?
Sea level rise of about 2m
Give an example of a ria ?
Kings bridge estuary , south Devon
How long is kings bridge estuarary in km ?
8.6 km
