Glaciation features Flashcards
define plucking
plucking is when glacial ice melts due to friction as it goes over an obstacle such as rock mass (1)
water refreezes around the loose rocks and as the glacier moves, loose pieces of rocks are picked from the ground (1)
define abrasion
material stuck to the bottom of the glacier also scrapes at the bottom and the sides, acting like sandpaper. this process is known as abrasion (1)
this is when rocks have been ripped from the ground and are now attached to the bottom of the glacier and scrapes the land below like sandpaper which steepens and deepens the valley
define freeze-thaw weathering
Freeze thaw weathering also helps steepening and deepening the valley. this is when water freezes in the cracks and crevices and expands by 9%
ultimately, splitting rocks into fragments
what formations are for erosional processes
corrie
arete
pyramidal peak
u shaped valley
hanging valley
ribbon lake
what can you write at the start of all erosional processes formation answers
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
what is the formation of a corrie?
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
as the mass of ice increases, its weight and gravity causes a rotary action so the ice rotates out the hollow. this is called a rotational slip
as loose rock is moves the rocks at the bottom of the hollow is pulled out… plucking (define plucking)
At the back of the hollow, a gap called the bergschrund is formed as the ice pulls away. this gap allows melt water to get under the ice and freeze thaw can take place,
(define freeze thaw)
(define abrasion)
At the front of the hollow there is less pressure so a lip is formed. during warmer periods ice may melt depositing debris on the lip. trapping rainwater, this can be known as a corrie lochan or a tarn.
ag red tarn in the lake district
what is the formation of an Arete?
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
as the mass of ice increases, its weight and gravity causes a rotary action so the ice rotates out the hollow. this is called a rotational slip
as loose rock is moves the rocks at the bottom of the hollow is pulled out… plucking (define plucking)
At the back of the hollow, a gap called the bergschrund is formed as the ice pulls away. this gap allows melt water to get under the ice and freeze thaw can take place,
(define freeze thaw)
(define abrasion)
At the front of the hollow there is less pressure so a lip is formed. during warmer periods ice may melt depositing debris on the lip. trapping rainwater, this can be known as a corrie lochan or a tarn.
An arête is a knife-edge ridge, formed when two neighbouring corries run back to back. As each glacier erodes either side of the ridge, the edge becomes steeper and the ridge becomes narrower.
eg striding edge
define a pyramidal peak
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
as the mass of ice increases, its weight and gravity causes a rotary action so the ice rotates out the hollow. this is called a rotational slip
as loose rock is moves the rocks at the bottom of the hollow is pulled out… plucking (define plucking)
At the back of the hollow, a gap called the bergschrund is formed as the ice pulls away. this gap allows melt water to get under the ice and freeze thaw can take place,
(define freeze thaw)
(define abrasion)
At the front of the hollow there is less pressure so a lip is formed. during warmer periods ice may melt depositing debris on the lip. trapping rainwater, this can be known as a corrie lochan or a tarn.
A pyramidal peak is formed where three or more corries and arêtes meet. Glaciers erode backwards towards each other, carving out the rocks by plucking and abrasion.
eg Hevellyn
State the formation of an U-shaped valley
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
The weight of the glacier as well as gravity and the build up of ice pushing it down from the Corrie causing the ice to flow down existing v shaped valley.
Define plucking
Define abrasion
Define freeze thaw weathering
Former interlocking spurs may be cut off the glacier as it flows downhill leaving truncated spurs and steep valley sides. This changes it from a v shaped valley to an U shaped valley
The width and shape of the resulting glacial trough will depend on the nature of the rock type and the intensity and weight of thr glacier. A softer rock will erode more easily than a more resistant rock
Eg langsdale valley
State the formation of a hanging valley
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
The weight of the glacier as well as gravity and the build up of ice pushing it down from the Corrie causing the ice to flow down existing v shaped valley.
Define plucking
Define abrasion
Define freeze thaw weathering
Former interlocking spurs may be cut off the glacier as it flows downhill leaving truncated spurs and steep valley sides. This changes it from a v shaped valley to an U shaped valley
The width and shape of the resulting glacial trough will depend on the nature of the rock type and the intensity and weight of thr glacier. A softer rock will erode more easily than a more resistant rock
Tributary valleys have smaller less powerful glaciers which result in less deep u-shaped valleys ‘hanging’ round the main valley. Known as hanging valleys
Eg Grisdale
What is the formation of a ribbon lake
(state the formation of a glacier)
as temperatures fall, previous years snow stays un-melted and new snow falls on top of it, causing the snow to be compacted which pushes all air out, forming glacial ice called the nevee. (1)
this is more likely to happen in the north facing hollows due to them facing away from the sun
When the glacier moves down through the Ushaped valley under its own weight and due to gravity, it will erode a Ushaped valley for itself
It will sometimes reach an area where the rock and soil below is much softer
This means that the glacier is able to gouge much deeper into the valley floor creating a long narrow, deep area in the base of the valley. This is done through
Plucking
Abrasion
Freeze thaw
After the ice age, the water from the misfit stream will fill up this ‘basin’ in the valley floor creating a ribbon lake
A ribbon lake can also be formed where a glacier increases in weight and erosive power causing it to surge forward
This could be dine during a colder period where snow and ice is being added in the Corrie, thus adding weight which moves the glacier forward
What is the formation of terminal moraine
Terminal moraine is a ridge across the valley and is made up from glacier deposits/ boulder clay which is unsorted so has basically been dumped by the ice
As the glacier moves downhill it acts like a bulldozer, pushing sediment in front of its snout as it goes
On reaching lower altitudes and when temperatures rise, the glacier melts, loosing power and depositing the moraine that it has been pushing along
Terminal moraine marks the furthest point that the glacier reaches
Once the ice is retreated, the terminal moraine can often form a natural dam, creating a moraine dammed lake
The glacier can move like a conveyer belt and if it stays in one place material can be moved to the front, adding to the terminal moraine.
What is the formation of an esker
Eskers are meandering ridges formed by meltwater streams in or underneath a glacier
They are therefore made up from meltwater deposits such as sand and gravel
These are sorted by size with larger stones at the base because larger stones are dropped first by flowing water and smaller deposits will be carried further
The stones also tend to be more rounded than unsorted glacier deposits because if the action of flowing water
This process is known as attrition where rocks are carried along the water and hit off each of them, chipping away and rounding them
As the glacier melts, sun glacier streams flow through tunnels or under the ice and the load is deposited on the floor of the u-shaped valley
Explain the formation of a drumlin
Drumlins are elongated hills made up of unsorted glacial deposits/ boulder clay
Drumlins are formed when glaciers become overloaded with sediment and deposits it, streamlining the sediment as it flows over it
It can also be created during warmer periods where the ice melts a little, depositing ground moraine carried beneath it but still is moving forward flowing downhill, under gravity, and thus shaping the moraine
If there is a small obstacle such as particularly resistant rock, this may act as a trigger point and boulder clay can build up around it
Drumlins can be reshaped by further ice moments after being organically deposited
Drumlins are found in swarms or in a ‘basket of eggs’ topography
