Glacial Systems And Landforms Flashcards
How does latitude affect the distribution of cold environments?
The higher the latitude, the less solar radiation (energy/heat) the earth receives from the sun - meaning there is colder temperatures in some areas
How does altitude affect the distribution of cold environments?
The higher the altitude, the lower the temp due to lower air density
How does relief affect distribution of cold environments?
the shape and slope (relief) of the land may prevent ice accumulation
If the slope is too steep the snow and ice may slide down the peak rather than just accumulating
How does distance from moisture source affect the distribution of cold environments?
precipitation is more likely to occur near a water source.
How is solar variation a cause of ice ages?
Reduced solar variation could lead to colder winters as suns UV radiation affects atmosphere circulation. This is impacted due to earths tilt relative to the sun.
How do Milankovitch cycles cause ice ages?
The impacts of the earth’s position relative to the sun are a strong driver of the long term climate - and triggering glacial periods.
What is the quaternary period?
The latest period of geographical time, spanning the last 2 million years
What are causes of polar and tundra climates?
- low levels of insolation
- the high albedo
- high pressure systems
- coolness of the air
- Katabatic winds
What is the vegetation in tundra like?
V low levels of biodiversity due to low levels of productivity
Absence of full grown trees - short growing season
What are some plant adaptations?
Ground hugging cushion plants to avoid wind
Slow growth rates
Shallow roots - avoid permafrost
Ability to photosynthesise at low temperatures
- low albedo
What is a system?
a system is a set of interconnected parts that work together. They have a series of stores or components and have flows between them.
What is an open system?
Inputs, outputs and stores and both energy and matter can be transferred into surrounding environment
What is the glacial budget?
How much goes in and how much goes out. The total of accumulation and ablation for a glacier.
What is accumulation?
The process of building up snow and other frozen precipitation, like meltwater and firn.
What is ablation?
The process of wastage of snow or ice by melting, sublimation and calving.
What is the equilibrium line/ zone?
The line or zone on a glacier’s surface where a year’s ablation balances a year’s accumulation.
What is calving?
The process of detachment of icebergs and smaller blocks of ice from a glacier into water
What is glacier advance?
the forward movement of the snout of the glacier following successive years of positive mass balance.
What is glacier recession?
the shrinking of the snout of a glacier following successive years of negative mass balance. Also referred to as glacial retreat.
What is the snout of a glacier?
the lower part of the ablation area of a valley glacier, commonly shaped like the snout of an animal.
What is a glacier?
a mass of ice, irrespective of size, derived largely from snow, and continuously moving from higher to lower ground.
What is a valley glacier?
A glacier bounded by the walls of a valley, and descending from high mountains, from an ice cap on a plateau, or from an ice sheet
What is an ice cap?
A dome shaped mass of glacier ice, usually situated in a highland area, and generally defined as covering up to 50,000 square kilometres
What is a piedmont glacier?
A glacier that spreads out as a wide lobe as it leaves a narrow mountain valley to enter a wider area or a plain.
What is a cold-based (polar) glacier?
Occurs in polar latitudes where the temperatures of snowfall is far below freezing and glacier remains at well below freezing point
What is a warm-based (temperate) glacier?
Water is present throughout the ice mass and acts as a lubricant
What is Nivation?
annual and diurnal temperature changes lead to thaw-freeze alternation, and the conversion of snow to ice crystals.
How does a glacier form?
Snow collects in a hollow. When summer periods are cool it doesn’t melt. This mainly happens on north facing slopes. Over time, the weight of the snow compresses the snow beneath it forming a firm. This is called sintering. Nivation also helps this process by melting the snow crystals and refreezing them into ice. After 20 years of continued accumulation of snow and firn formation means all the air is squeezed out and glacier ice is formed.
What are the 5 ways the glacial ice moves in once formed?
- Internal deformation
- Rotational (movement at the start of a glacier in a corrie)
- Compressional
- Extensional
- Basal sliding
What is basal sliding?
the sliding of a glacier over bedrock, a process usually facilitated by the lubricating effect of meltwater.
What is rotational flow?
- A downhill flow of ice which, like a landslide pivot, around a point producing a rotational movement.
What is a crevasse?
A deep v-shaped crest formed in the upper brittle part of a glacier as a result of the fracture of ice undergoing extension.
What is a Corrie?
An armchair shaped hollow with steep sides and a back wall, formed as a result of glacial erosion, high on mountain side, and often containing a rock basin with a tarn.
Where are corries formed?
Where glacier begins. When ice melts, water often collects at the base of the Corrie to form a tarn lake.
What is the formation of a Corrie?
Snow collects in a natural hollow at the side of a mountain. More snow collects over time, compressing the snow underneath it turning it into ice. The hollow is deepened and widened by the Corrie glacier through the processes of abrasion and plucking. This over deepening gives it the armchair shape. They often reflect multiple phases of glaciation.
What are arêtes?
A sharp, narrow, often pinnacled ridge, formed as a result of glacial erosion from both sides.
What is a Glacial trough?
A glaciated valley, often characterised by steep sides and a flat bottom, resulting primarily from erosion by strongly channeled ice.
What are truncated spurs?
Former interlocking spurs in a v-shaped valley are bulldozed away by a glacier creating truncated spurs - blunt triangular ends found at the dies of glacial troughs.
Steeped long profile in a glacial trough
What is a hanging valley?
A tributary valley where the mouth ends abruptly part way up the side of the main valley, as a result of the greater amount of glacial down-cutting of the latter.
What are Roche mountonnees?
A rocky hillock with a gently inclined smooth-up valley facing slops resulting from glacial abrasion, and a steep, rough down-valley facing slope resulting from glacial plucking.
Developed when ice formed to flow and deform round an obstruction.
What is a tarn?
A small, deep, circular lake. Widened and deepened by valley glacier
What is erratic?
A boulder or large block old red rock that has been or is being pushed up by a glacier during an advance
What are till plains?
Wide areas of generally flat relief created by a till sheet
What are drumlins?
Oval shaped hills, largely composed of glacial drift
What is lodgement till?
subglacial material that was deposited by the actively moving glacier. A typical feature formed in this manner is a drumlin.
What is ablation till?
produced at the snout when the ice melts. Terminal push and recessional moraines are typical features produced from ablation till.
What is a moraine?
A type of landform which develops when the debris carried by a glacier is deposited
What are fluvioglacial processes?
Processes which involve erosion, transport and deposition by meltwater
What is a valve?
a layer of silt lying on top of a layer of sand, deposited annually in lakes found near to glacial margins.
What are eskers?
Eskers are ridges made of sands and gravels, deposited by glacial meltwater flowing through tunnels within and underneath glaciers, or through meltwater channels on top of glaciers
How big are eskers?
Can be up to 30km high and several km in length
What type of feature are eskers?
A depositional feature
What are the 3 main types of kames?
- kame terrace
- kame delta
- crevasse kames (just kames)
What are kame terraces?
- the largest type
- formed as the infilling of a marginal glacial lake sediment is deposited between the valley side and the ice mass
- Sediment is more sorted than other types of kames
- Post glaciation they are visible ridges on the sides of valleys
What are kame deltas?
- Smaller than terraces
- They form small mounds of sediment on the valley floor where a meltwater stream enters a marginal lake or pro-glacial lakes
- They appear as small hills on the sides of valleys or more central
What are crevasse kames (just kames)?
- Occur where meltwater streams enter the glacier through surface crevasses
- Material is deposited in the valley floor in a pudding bowl shape
What are Kettleholes and how do they form?
Kettleholes form in the following way:
• As the glacier retreats it may leave large blocks of buried ice
• This ice slowly thaws over time and the covering gravel collapses leaving a depression
• These depressions are called Kettleholes
• If the depressions are deep enough to tap the water table a kettle hole lave forms
What are Outwash plains and how do they form?
An outwash plain is an extensive, gently sloping areas of sands and gravels formed in front of a glacier. It results from the ‘outwash’ of material carried by meltwater streams and rivers. During a glacial period, meltwater and the deposition of outwash can be very seasonal, being mainly restricted to the summer months. However, at the end of a glacial period, huge quantities of material will be spread over the outwash plain by great torrents of meltwater.
What are Periglacial processes?
Areas that are not glaciated but are exposed to very cold conditions with intense frost action and permafrost
What are the factors of a Periglacial climate?
- Persistently low temperatures
- Short summers but summer temps can exceed 15 degrees Celsius
- Winter temps are well below 0 degrees Celsius. In some areas, they may fall as low as -50 degrees Celsius.
When does permafrost occur?
When subsoil temperatures remain below 0 degrees Celsius for 2 consecutive years
What is an active layer?
During the summer, the surface layer of soil thaws to form an active layer
What are the 3 types of permafrost?
Continuous permafrost
Discontinuous permafrost
Sporadic permafrost
What is continuous permafrost?
found in coldest regions. Hardly any melting in the upper layers
What is discontinuous permafrost?
occurs in regions that are slightly warmer. There is also gaps in the frozen areas under rivers, lakes and near the sea.
What is sporadic permafrost?
mean annual temps are around freezing. Permafrost occurs only in isolated spots where the local climate is cold enough to prevent complete thawing in summer months.
What is frost heave?
- results from direct formation of ice crystals in the soil when the active layer refreezes
- this causes fine-grained soils to dome upwards as they increase in volume (ice expands)
- within the soil any stones will cool down faster than the fine-grained soil. Any moisture below these stones will freeze, turning to ice and expanding, pushing the stone upwards
What is Solifluction?
- when the active layer melts in summer, excessive lubrication reduces the friction between soil particles
- parts of the active layer begin to move downslope
How are ice wedges formed?
- refreezing of active layer during winter causes soil to contract and cracks open up on the surface.
- these fill with meltwater and deepens the crack
- this eventually forms an ice wedge and depends over the years
What is thermokarst?
- a landscape formed by the dissolving action of water
What is the concept of environmental fragility?
Some ecosystems can cope with wide variations in climactic conditions and land-use impacts, whereas others are more sensitive to any environmental change. Effects of small shifts in rainfall patterns or ambient temperatures and often do great harm to fragile environments.
In what ways are cold environments fragile?
- plants are very specialised to their environment - small changes have a large impact on
- sensitive to change - ecosystem will take a long time to recover
- short growing season - plants don’t have much time to recover from damage
- limited species diversity and low productivity
- plants and animals are adapted to the cold conditions - further adaptations to changes are verity slow
- decay is slow because its cold, pollution is broken down very slowly
What does management of cold environments need to focus on?
Preserving cold environments and sustainability
What are the three management approaches for cold environments?
- prevention
- reaction
- adaptation
What is prevention?
attempting to prevent a harmful event from occuring. E.g oil spills or insulating pipes to prevent melting of the permafrost
What is reaction?
responding to an event once it has occurred. E.g. clearing up the oil spill. Helping a ski-slope to recover
What is adaptation?
learning to live with change. E.g. changing hunting methods, farming practices, living with climate change, building houses to cope with the permafrost.
How are kames formed?
(Mark scheme)
Kames are formed by fluvioglacial depositional processes. They are composed of sand and gravel and form when meltwater enters a moraine dammed lake. Kame deltas form into mounds on the cellar floor. Kames are formed at snout or beneath glaciers. Kame terraces are found along the side of glacial valleys. These are a product of the deposition by meltwater flowing between the glacier and valley side.
(Easier to remember)
Kames are accumulations of partially-sorted material found at the front of a melting or stationary glacier. These mounds build up in height as a glacier melts and meltwater streams carry material from within and under the glacier to be deposited immediately in front of the glacier into meltwater lakes.
