Glaciers Flashcards
Characteristics of glacial environments
Snow and ice covering most of the landscape.
Consistently low temperatures.
Development of significant amounts of snow and ice led to formations of glaciers.
Glaciers radiated from the north and west and carved deep glacial valleys and troughs.
What is an ice age ?
A period of long-term cooling of the Earth’s atmosphere, resulting in an expansion of ice sheets and glaciers.
Glacial abrasion
The sandpaper effect caused by the weight of the ice scouring the valley floor. It leaves a smooth, polishes surface. Scratches called striations caused by large rocks beneath the ice can often be seen.
Plucking
When the meltwater beneath the glacier freezes and bonds the base of the glacier to the rocky surface below, like glue. As the glacier moves, loose fragments of rock will be ‘plucked’ away. This leaves behind a jagged, rocky surface.
Basal slip
Where meltwater acts as a lubricant to the glacier, enabling it to move downhill. This can be sudden and occurs more in summer months.
Glacial rotational slip
Where ice moves along a curved surface to enlarge + develop hollows.
Internal deformation
In winter, the glacier becomes frozen to the rocky surface. The weight of the ice and the influence of gravity causes individual ice crystals to change shape in a plastic-like way. This causes the glacier to move downhill.
Bulldozing
Renewed further movement of the glacier pushes depositional material downhill. The buildup of sediment can form a hummock, which is a small mound of sediment.
Where is deposition of material carried in the glacier found ?
The snout
What causes glacial deposition ?
Constant transport of new, debris-laden ice into lowland areas results in deposition of all the eroded and weathered material from the uplands. This is called till.
What is till ?
Poorly sorted debris carried by the ice and dumped when the ice melts. It comprises of a range of particle sizes and tends to be angular, having had little water transport.
What is outwash ?
Carried by meltwater streams - is rounded and well-sorted, with gradually finer materials being deposited with distance away from the ice front.
What is an arete ?
Also known as a free-thaw ridge.
A knife-edged ridge formed when 2 corries develop side by side or back to back. As the 2 corries erode towards each other, a ridge is formed between them.
Eg. Striding edge, Lake District
What is a hanging valley ?
A tributary valley that is higher than the main valley.
Formed when a tributary glacier flows from the valley sides towards the main glacial valley.
As the glaciers flowed through the rock on the valley sides, they eroded smaller tributaries into the valley sides, leaving valleys ‘hanging’ over the valley below.
Eg. Nant Lilau, Snowdonia
What is a pyramidal peak ?
A peak formed when 3 or more corries develop on all sides of a mountain.
Eg. Stob Dearg, Scotland
What is a truncated spur ?
A blunt ended, sloping ridge which descends from the flank of a valley.
Formed by the force of a glacier bulldozing through a valley, removing large portions of the valley sides.
Eg. The Devil’s Point, Scotland
What is a glacial trough ?
Before glaciation, a river valley would’ve been v-shaped.
During glaciation, the rock in the valley sides is removed through plucking and abrasion.
This results in a U-shaped valley or glacial trough. It has steep sides and a flat, wide valley floor.
Eg. Glencoe, Scotland
What is a corrie ?
A deep, armchair shaped hollow found on the side of a mountain where a glacier was once found.
When the glacier melts, it leaves a lake called a tarn.
Eg. Red Tarn, Lake District
How is a corrie formed ?
Snow accumulates in a sheltered hollow on a hillside.
Nivation enlarges the hollow enabling more snow to collect.
Gradually, the snow turns to ice and a small corrie glacier is formed.
Through rotational slip, the glacier abrades an over-deepened hollow.
Reduced erosion at the front of the corrie, due to the ice being thinner and less erosive, forms a raised lip.
Sometimes moraine may be deposited here.
A tarn may form in the bottom of the corrie.
What are ribbon lakes ?
Long narrow lakes in glacial troughs.
Formed in the base of the glacial trough once the ice has melted, they may be created in an area of soft rock, where the glacier has eroded this area deeper.
The meltwater sits in the depression and leaves a ribbon lake.
What is a drumlin ?
A small egg-shaped hill, often found on the floor of a glacial trough.
Elongated features that can reach 1km in length, 500m in width, and over 50m in height.
Steep Stoss end, shallow Lee end
How are drumlins formed ?
Formed when the glacier deposits material. As the glacier is carrying so much, it is overloaded and struggles to carry it as it is nearer the end and is melting.
Small obstacles lead to moraine being deposited around them as the ice cannot overcome them and carry material.
The moraine moulds around the obstacle, the blunt end being the deposited material upstream of the ice, and the long tapered end where the ice has flowed over and trailed the moraine with it.
When the ice sheet moves over the material, it shapes it, depending on the direction of ice flow.
What are erratics ?
Rocks that have been transported by ice and deposited elsewhere. This lithology that the erratic is made from is different to the lithology of the bedrock where the erratic is deposited.
What is moraine ?
Deposited material from a glacier
Ground moraine
Material that has dragged underneath the glacier, which is left behind when the ice melts.
Lateral moraine
Forms on the side of a glacier. Mostly made of scree, fallen from the edges of the valley.
Medial moraine
When a tributary glacier joins a smaller one, 2 lateral moraines merge into one. When ice melts it forms a ridge in the middle.
Terminal moraine
Huge amounts of moraine build up at the end of a glacier. It marks the maximum extent of ice coverage.
Recessional moraine
Marks where the glacier once was, as it retreats back, material is deposited.
Why does sheep farming take place in glaciated upland areas ?
Sheep can tolerate the cold, wet and windy conditions.
In summer, sheep graze the steep valley slopes, and in winter, they are brought down to the valley floor.
Eg. 50% of ewes are reared in glaciated areas.
Wool + meat can be sold, sheep can be traded.
Why does arable farming take place in glaciated upland areas ?
Soils in the valley bottoms are thicker, and the flat-bottomed glacial trough is ideal for machinery. This fertile land is used for growing cereals and potatoes, due to the less harsh climates. It is also used for growing grass, stored as silage or hay for feeding livestock.
Eg. Nantle Valley
Prices can be raised due to sought-after location.
Why does tourism take place in glaciated upland areas ?
Spectacular glacial scenery, opportunities for hiking, walking and biking.
Tarns and ribbon lakes are ideal for watersports.
Eg. Lake District, Beatrix Potter, 16 million visitors spend £900 million pounds yearly.
Creates jobs and boosts economy.
Why does forestry take place in glaciated upland areas ?
Large plantations of conifers due to adaptations to acidic soil. Can be left for 20-30 years before being felled for timber or making paper.
Eg. Trossachs National Park - large areas of plantations for industrial-scale forestry.
Viable source of money for land-owners, other than farming.
Why does quarrying take place in glaciated upland areas ?
Hard resistant rock can be quarried and crushed to provide construction-level stone and material for roads.
Eg. Limestone makes up majority of the Pennine Hills, a valuable resource used in the chemical industry for making cement and conditioning soils.
Provides minerals which can be used in building, power and electricity. Useful for the expanding population.
Conflict of quarrying in glaciated areas
Pollution of land and rivers, destroys habitats, spoils landscape, noise pollution due to transport and processes
Conflict of tourism in glaciated areas
Drop litter, erode footpaths, scare sheep, trample on crops, leave gates open. Land is used for gift and coffee shops instead of farming. Increase in house prices due to popularity.
Conflict of sheep farming in glaciated areas
Removes vegetation from area.
Conflict of forestry in glaciated areas
Destroys habitats, aids global warming, coniferous woodlands do not support as many species as natural woodlands
Conflict of military training in glaciated areas
Engine noise disrupts transquility.
Glenridding zipwire 2014
Windemere company Treetop Trek put forward a proposal to construct 4 parallel 1-mile zip wires. They would run from a disused mine in the national park and reach a field above Glenridding.
Plan did not go through after conflict with the public, despite the economic opportunity it may have brought.
Physical attractions of the Lake District
Mountainous landscapes with peaks such as Scafell Pike are popular with hikers and bikers.
Lakes eg. Windermere attract fishing, watersports, cruises
Adventure activities eg, abseiling, rock climbing
Cultural attractions of the Lake District
Beatrix Potter’s home, a National Trust site
Muncaster Castle, a historic site
The landscape has inspired many writers, eg William Wordsworth
Social impacts of tourism in Lake District
In 2018, 20 million tourists visited, compared to the 40,000 locals.
83% of visitors travel by car, creating congestion.
High house prices, 20% of houses are holiday homes.
Jobs in tourism are poorly paid and seasonal.
Economic impacts of tourism in Lake District
In 2019 tourists spent £3 billion.
Provides employment for 65,000 locals.
New businesses fuelled by tourism provide new jobs for locals.
Traffic congestion slows business communications.
Environmental impacts of tourism in Lake District
Signs of overcrowding - footpath erosion, litter, damages to verges from cars.
Pollution from vehicles damages ecosystems.
Walkers damage farmland by trampling crops or leaving litter, dogs disturb sheep and cattle.
How is congestion in the Lake District managed ?
The Go Lakes Programme - a £6.9 million initiative, funded by the government. Aims to :
Improve public transport
Develop integrated walking and cycling networks
Create transport hubs with integrated ticketing
Expand park and ride systems
How is footpath erosion managed in the Lake District ?
The Fix The Fells charity maintain and repair mountain paths, supported by the national trust.
The Upland Path Landscape Restoration Project has repaired paths, created steps, and resurfaced paths with local stone and native plants.
