Lithosphere Flashcards
processes of erosion
FREEZE THAW
water enters the cracks and crevices the expands when frozen, shattering the rock. this then repeats until the rock falls apart.
PLUCKING
loose pieces of rock are pulled from the rock as the glacier moves
ABRAISION
pieces of rock embedded in the glacier ware away the rock underneath
Arête
a thin ridge of rock formed between to adjacent or parallel glacially eroded valley. the ridges are further sharpened by the actions of freeze thaw.
PYRAMIDAL PEAK
an angular and pointed peak.
formed when 3 or more carries surround a mountain and erode backward into it.
Fiord
when a glaciated valley is submerged by a rise win sea level
alluvial fan
caused when a stream falling from a side valley reaches flatter ground on the valley floor. material is the dropped
Crag and tail
these are partially erosional partly depositional feature
the rock facing the ice is steepened by glacial erosion. the softer rock on the other side is ported from erosion to form a fail of boulder clay
formation of scree
scree forms on steep rock faces with lines of weakness
water seeps into cracks and fractures in the rock
when the water freezes it expands about 95 in volume which wedges the rock apart
with repeated freeze thaw cycles the rock breaks into pieces
THE SCREE THAT FALLS FROM THE ROCK FACE COLLECTS AT THE BOTTOM TO FORM A TALLUS SLOPE
Erratics
these are large rocks that are completely different to the rocks on which they rest
they were carried by the ice sheet, sometimes for hundreds of KM, then deposited
Esker
these are glacial streams that are found under the ice.
they are loaded with debris(sand and gravel) that is carried by the meltwater
as the ice retreats, the river deposits its load.
the built up river bed is called an esker
Drumlin
there are smooth, rounded mounds of ground moraine. the steep sides face the direction the ice moved from
drumlins ofter occur in swarms or groups on the valley floor
formation of a stump
lines of weakness occur in a headland
an area of headland= band of more resistant rock surrounded my softer rock
fault is widened by 2 process of erosion
abraison=rocks/pebbles are thrown at the coast by the waves
hydraulic action= when the water enters the cracks and compresses the air within causing a mini explosion. widens the weaknesses to form a cave
waves cut through to form an arch which is continually widened at its base through hydraulic action
roof becomes too heavy and collapses leaving part of the former cliff as a stack
over time, the stack is undercut through abrasion and hydraulic action and collapses(base is too narrow to support it) leaving a stump
Wave cut platform
The waves attack the base of the cliff through the processes of abrasion corrosion hydraulic action and attrition
Over time the cliff will be undercut and a WAVE CUT NOTCH is formed
Eventually the cliff becomes unstable and collapses. Further cliff retreat will form a WAVE CUT PLATFORM
Headland and bays
Headlands and bays form along coastlines where there are alternating outcrops of resistant and less resistant rock.
Destructive waves erode areas of softer rock more rapidly to form bays.
The waves cannot wear away the resistant rock so headlands are left protruding out into the sea
These are now more exposed to erosion
Formation of a cove
Coves form in areas where there is a band of resistant rock parallel to the sea with softer rock behind.
The sea exploits faults/weaknesses in the rock through abraison and hydraulic action
Waves erode through to a softer rock.
WAVE processes of erosion erode the softer rock leaving a circular cove with a narrow enterance
Longshore drift
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This is the movement of sediment along the coastline
Direction in which the sand travels is related to the prevailing wind
The waves hit the beach at an angle(swash)
Due to the gravitational pull of the earth, leave the beach at a right angle(backswash)
Bars
A bar is formed as a spit grows across a bay joining up two narrow headlands
Longshore drift brings material down the coast. A spit grown across the mouth of the bay between the two headlands.
Behind the bar, a lagoon will form which will gradually infill through deposition
Tombolo
EXPLAIN HOW A SPIT FORMS
the spit builds up out to the sea and joins into an island. This is a tombolo
Spit
Longshore drift transfers sediment along the beach
The change in shape of the headland creates a sheltered environment so waves have less energy and deposit sand/shingle which builds up the spit which then extends in length as more is deposited
Recurved laterals are created due to the change in wind direction but continue
when wind direction goes back to normal
A salt marsh is created behind the spit= low energy zone so sediment is deposited
Spit may be stopped from a movement of water in a different direction =ESTUARY
Spit becomes permanent when sand is blown up the beach to form sand dunes
Formation of a bay
- forms when a variety of different types of rocks can be found
- the hard rock erodes slower
- the soft rock erodes quicker
- where hard rock is at either side of softer rock, the softer rock erodes away leaving a bay
Key stages in the formation of a glacier
- snow collects in the North/East facing hollows
- the weight of lots of snow compresses air out of it making it a neve layer(half ice, half snow)
- the melting and refreezing that occurs leaves areas partly ice(firn|)
- eventually the weight of the snow pushes all the air out and it becomes solid ice
Processes of erosion of a coast line
HYDRAULIC ACTION
-water entering the cracks in the rock and compressing the air within, causing a mini explosion and therefore shattering the rock
CORRASION
-Force of rocks being thrown at the cliff, which wear away the coastline
CORROSION
-this is the chemical action of the sea water. The salty sea water(acidic) slowly dissolves the coastline (limestone and chalk are particularly prone to this
ATTRITION
-materials carried by the waves bump into each other and are smoothed/ worn/ broken down down into smaller particles
how can you tell if an area is glaciated?
- bare rock symbols
- scree
- mix of different contours
- horse shoe shaped contour lines
- u shaped valley
- misfit stream
