Glacial Landscapes Flashcards
Describe the formation of a pyramidal peak
During a period of glaciation, snow gathers in hollows on a mountain-side. As the snow builds up, the ice compacts and three or more corrie glaciers form
Due to the weight of the ice and gravity, the corrie glaciers begin to move. the glaciers move forward slowly, eroding the landscape beneath, making the hollows bigger
Ice sticking to the backwall pulls away blocks as glacier moves. This is known as plucking. Over time, the erosion of the backwall causes the corries to cut into the mountain-side further
The erosion results in a sharp pyramidal peak with radiating arêtes. An example Helvellyn in the Lake District
Describe the formation of a hanging valley
During a period of glaciation, snow occupies a tributary river valley.
As the snow builds up the ice compacts and a glacier forms
Due to the weight of the ice and gravity, the glacier begins to move
The tributary glacier moves forward slowly, feeding into the main glacier. The glacier erodes the landscape beneath
As the glacier moves, the processes of abrasion and plucking are at work.
Over time, these processes result in the widening and deepening of the valley, giving a characteristic u- shape.
Tributary glacier is unable to erode the land as much as the main glacier so when the glaciers melt, the tributary valley is left hanging high up above the main glacial trough
Describe the formation of a glacial trough
During a period of glaciation, a glacier occupies a former v-shaped valley. As the snow builds up, the ice compacts and a glacier forms
Due to the weight of the ice and gravity, the glacier begins to move. It is unable to wind around the interlocking spurs like a river does
As the glacier moves, the processes of abrasion and plucking are at work.
Over time, these processes result in the widening and deepening of the valley, producing steep sides called truncated spurs, and a flat valley bottom
What is abrasion?
Abrasion occurs when the rocks carried along the bottom and side of the glacier wears away the sides and base of the valley
What is plucking?
Plucking occurs when the ice sticks to the rock and pulls out loose fragments as the glacier moves forward
Name all of the lower glacial features
Hanging valley
Truncated spurs
Glacial trough
Name all of the upper glacial features
Arete
Tarn
Pyramidal peak
Corrie
What are some features of a corrie
Steep backwall
Rock lip at the front of the corrie
Often has a circular lake, but not always
Describe the formation of a corrie
During a period of glaciation, snow gathers in a small hollow in a mountain-side. As the snow builds up it becomes compressed and turns into glacial ice
Due to the weight of the ice and snow, the ice begins to move, forming a glacier. It is lubricated by water at the base. As the ice moves forward it does so in a circular motion known as a rotation slip
Ice sticking to the backwall pulls away blocks as glacier moves. This is known as plucking.
Loose rocks from freeze-thaw weathering and plucking become embedded in the ice which then scape of the bottom of the corries by erosion
After the ice melts, a deep circular hollow with a steep backwall is left behind. This is known as a corrie. Often a circular lake forms in the centre of a corrie, known as a tarn
Why do corries normally face N/NE/E/SE?
The sun rises in the east and spends most of teh day in the south. This means that when the corry was formerly a glacier, the south and the west sides wouldn’t have as much time to build up and would melt more than the north and east side.
Why does a glacier deposit?
- The ice melts
- When the ice is overloaded with material (not enough energy to transport it all)
- When it hits an obstacle
What is glacial till?
Broken rock fragments
- Unsorted
- Angular (due to FTW)
- Also known as boulder clay
What is glacial outwash?
Sandy and gravel material deposited by melting ice
- sorted (larger ones near snout, smaller ones further away)
- rounded (due to attrition)
What are moraines?
They are piles of glacial till that are carried and deposited by a glacier
What are the different types of moraine?
Lateral moraine Medial moraine Ground moraine Terminal moraine Recessional moraine
What is a lateral moraine?
Piles of material deposited at the side of the glacier
What is a medial moraine?
Piles of material deposited along the centre of the valley floor. (Formed when 2 lateral moraines join up)
What is a ground moraine?
Piles of material left behind by a melting glacier spread over a wide area (forming a hummocky surface)
What is a terminal moraine?
A semi-circular mound of material extending across a valley which was dropped at the snout of the glacier-the further point reached by the ice
What is a recessional moraine?
Piles of material in narrow ridges across the valley-showing where the ice is receding from
Describe the formation of a lateral moraine
During a period of glaciation, a glacier occupies a former v-shaped valley.
The glacier moves slowly through the valley due to gravity and the sheer weight of the ice
High up on the valley sides, above the glacier, freeze thaw weathering takes place
Repeated freezing and thawing weakens the rock and eventually it will drop down onto the glacier. Lots of fragments of rock are deposited and accumulate at the side of the glacier. This is known as lateral moraine
What is freeze thaw weathering?
Water enters cracks in rocks. When temperatures drop (usually at night), this water freezes and expands. this places pressure on the crack. When the temperature rise, usually during the day, the ice melts. This reduced the pressure on the crack
What are erratics?
Large boulders that have been transported and deposited far away
What are some of the characteristics of a drumlin?
- A low, egg-shaped hill
- 30-40 metres high
- 300-400 metres long
- blunt end, tapered end
Describe the formation of a drumlin
During a period of glaciation, a glacier fills a valley and slowly moves into lowland areas
At this point, the glacier is overloaded with material and melting is taking place
If the ice hits any small obstacle, such a s a resistant outcrop of rock/sediment, the ice will deposit some of its material
Most of the deposition occurs around the upstream and of the obstacle forming a brunt end which has a steeper slope
As the glacier moves slowly forward around the obstacle, it moulds further material on the downstream side creating a tampered end which is more gently sloping.
What are the economic uses of glaciated areas?
Farming
Forestry
Tourism
Quarrying
What sort of economical impacts are tourists are tourists having on North Wales
Lots of employment however it is seasonal and low-paid
Extremely high house prices
Price of goods are higher because of tourists
What sort of social impacts are tourists having on North Wales?
- Increased traffic, congestion and less parking
- Employment opportunities can prevent out-migration
- Ghost village as lots of homes are 2nd homes
What sort of environmental impacts are tourists having on North Wales?
- Footpath erosion, vegetation is tramples and destroyed and soil underneath is vulnerable
- Litter, BBQs and bonfires ruin landscape
- Water sports-noise pollution, fuel spills, waves erode the shoreline
What are some management strategies to manage the impact of tourism?
Provision of litter bins
Manage water sports-permits and certain boats banned (Llyn Tegid)
Information boards
Footpath maintenance-good signposting and repair with hard wearing stone
Facts about Snowdonia
1 million people walk Snowdon
91% arrive by car
Tourism worth £400M per year
10M visitors every year
What are scree slopes?
Loose pieces of sharp rock lying at the foot of a rocky slop
Formed by freeze-thaw weathering
What are misfit streams?
They are rivers that now appear to be too small for its valley
Resulting from a valley being enlarged and broadened by glaciation
What is a rouche moutonee?
Ice smoothened rock with a steeper jagged side facing down valley
Resistant rock remains after ice abrasion on the ice-direction facing side and plucking on the lee side
What are striatations?
Thin parallel scratches on rock surfaces
Formed by ground moraine in the ice which is dragged along the surface of the rock
Explain the formation of a ribbon lake
During a period of glaciation, a glacier fills a v-shaped valley.
Due to the weight of the glacier and gravity, the glacier moves slowly through the valley.
Processes that are involved are plucking and abrasion.
Over time, the valley becomes wider and deeper and sometimes overdeepens the valley floor.
This creates a ribbon lake. An example of this would be in the Lake District
