Glaciation Flashcards
How does the Milankovich cycle cause global climate change - eccentricity
Eccentricity - CIrcle maintains distance from sun, elliptical temp varies as distance does
How does the Milankovich cycle cause global climate change - wobble
Wobble - Earth wobbles on axis, effects earth’s seasonal pattern
How does the Milankovich cycle cause global climate change - tilt
Tilt - Changes how visible poles are to sun, temp differs
How does solar variation change global climate
‘Flares’ are on the sun, indicate suns radiation activity, Sunspots increase or decrease average temp
How do volcanic eruptions change global climate
Eruption produces ash and sulfur dioxide, spreads around stratosphere, temp on earth’s surface falls and cools
How do meteorological processes affect global climate
Intense cold leads to snow to accumulate in polar regions
What is the cyrosphere
Part of the earth’s crust and atmosphere which are subject to temp changes below 0 degrees
What is the hyrdological cycle
Process of water moving, being transfered and stored
How does ice affect the hydrological cycle
Ice is used as a substitute if there’s no percipitation
How might the cycle be affected by climate change
Temp rises, more glaciers melt, releasing more water. May disrupt ocean currents due to masses of fresh water released
What is an ice sheet
Masses of glacial ice, only 2 - Antartic ice sheet and Greenland ice sheet - unconstrained
What is an ice cap
A smaller ice sheet - unconstrained
Whats a valley glacier
Where the glacier was confined between the valley walls, formed by ice caps/sheets - constrained
What is a cirque glacier
A smaller glacier occupying a hollow on a mountain side - constrained
Whats an ice shelf
Large area of floating glacier ice - unconstrained
What affects present day ice cover
The altitude, latitude
What is periglacial
Areas at the edge of permanent ice, characterised by permafrost and tundra environment
What is permafrost
Where a layer of soil, sediment or rock below the surface remains permanently frozen
What is a warm based (temperate) glacier
Water present throughout the ice mass (lubricant), allows more movement - erosion, near the PMP (pressure melting point) so more melting
What is a cold based (polar) glacier
Occur in high latitudes, stay frozen so little movement - erosion, below PMP - so no meltwater/melting
What is the active layer
The top soil, freezes in winter and thaws in the summer
What is continuous permafrost
Affects (freezes) rock and soil up to 700m deep, temp ranges -5⁰c to -50⁰c
What is discontinuous permafrost
Affects rock and soil up to 20-30m deep, temp ranges -1.5⁰c to -5⁰c, there are breaks as the deep water doesn’t freeze
What is sporadic permafrost
Occurs in only isolated spots, temp ranges 0⁰c to -1.5⁰c
What is an ice lens
Moisture collects in the soil and freezes, expands and pushes land upwards
Whats a nivation hollow
Circular depressions in the ground. Created by a nivation, freeze thaw action and chemical weathering, these cause the rock to disintegrate. The weathered particles and snow moved downslope by meltwater, leads to formation of nivation hollow.
What are solifluction lobes
Tongue-shaped landforms. Created by solifluction, active layer thaws in summer, creates excessive lubricant, active layer moves downslope.
What is patterned ground
Symmetrical geometric shapes formed by ground material. Created by frost heave, active layer refreezes, causes upward expansion of soil - frost heave causes soil to expand unevenly, creates small domes on surface.
What’s a pingo
dome-shaped mound consisting of a layer of soil over a large core of ice. Created by groundwater freezing, in the core is an ice lens topped with soil.
What’s an open system pingo
Permafrost is discontinuous, water seeps in upper areas and freezes, groundwater seeps in and freezes creating a dome. Can break and becomes an ognip.
What’s a closed system pingo
Lakes from in depressions, water is trapped, sediment builds over top. Can break and becomes an ognip.
What’s an ice wedge
Crack in the ground formed by a narrow or thin piece of ice. Created by ground contraction, active layer refreezes, soil contracts, cracks open up, meltwater enters and process repeats. Process widens and deepens crack
What is mass balance
The net gain/loss of ice in a glacier
What is dynamic equilibrium
When the outputs and inputs are balanced
What is sublimation
Transition of a solid directly to a gas, doesn’t go to a liquid
What is the accumulation zone
Area above firn line, snowfall accumulates and exceeds losses of ablation
What is negative feedback
Regulates system to maintain equilibrium
What is positive feedback
These speed up processes promoting rapid change
What is altimetry
Provides repeated measurements of the ice sheet
What is gravimetry
The gravitational attraction of ice sheets
What is the mass budget method
Compares amount of snow on ice sheet and amount of meltwater
What is internal deformation
Occurs in polar and temperate glaciers, movement within ice due to stress by gravity, ice crystals slide past each other, movements create crevasses.
What is basal slippage
Occurs in temperate, glacier moves and raises temp of base ice, basal ice melts and acts as lubricant.
What is regelation
Occurs in temperate, occurs due to basal slip, PMP is passed so it melts, film of water formed so ice moves, water refreezes when pressure reduces.
What is extensional and compressional flow
Occur in temperate, Extensional - (above firn line) velocity increases in accumulation zone due to down valley ice consistently pulling away from up valley ice.
Compressional - (below firn line) velocity falls as upper valley consistently pushing against down valley ice.
What is a crevasse
A deep v-shaped cleft formed in upper part of glacier, due to fracture of ice
What’s a longitudinal crevasse
Crevasse oriented parallel to long axis of a glacier, open when glacier becomes wider
What affects rate of glacial movement
Altitude, lithology (rock characteristics), size, slope gradient and ice temp
What is abrasion
Where rocks carried by glacier collide with bedrock on floor
What is plucking
The pulling away of loose rocks or ice
What and how is an Arete formed
It is a narrow ridge of rock that separates 2 mountains, formed when 2 corries are back to back
What and how is a corrie/cirque formed
Its a hollow in a mountain with a large backwall, snow accumulates in hollow, freeze thaw weathering and plucking occur on backwall, moraine falls, abrasion deepens hollow, moraine gathers opposite backwall, river lake (tarn) may form in hollow
What and how is a Roches Moutonnees formed
Goes direction of glacier flow, stoss side is ramp like, lee side is cliff like. Glacier went over top, striations left due to abrasion, lee side vulnerable to plucking
What are knock and lochan
Knocks - small hills. Lochans - small lakes
What and how are crag and tails formed
The opposite of a Roches Moutonnees, glacier flow goes into hard volcanic rock, creates cliff like side where glacier hit first (crag), descending ramp on other side where softer rock is found (tail)
What is till
Mixed materials deposited by ice e.g. drumlins, moraines and erratic
What and how are drumlins formed
Like a small hill, glacier dropped debris, as it went past it deposited sediment, was then narrowed and straightened by glacier.
What is medial moraine
Ridge of rocks that form in middle of glacier, created by 2 lateral moraines
What is terminal moraine
The end of the moraine, where the glacier stopped/the furthest it got
What is lateral moraine
Forms on the sides of the glacier, due to glacier going past rocks and soil they drop to the side
What is recessional moraine
These are secondary terminal moraine, deposited when a temporary glacier standstill occurred
What is an erratic
A rock or boulder of different material than surrounding rocks, brought by glacier
What is lodgement till
Rounded clasts, due to grinding on ice bed, not within matrix of clay or silt size particles
What is ablation till
Angular clasts, not grounded down, matrix is of larger sized material and less compact
What’s an outwash plain
A plain formed of glacial sediments that is found at the snout of the glacier
What are braided meltwater streams
Streams that criss-cross the outwash plain
What are varves
Layers of sediments found in the bottom of lakes at the front of the glacier
What are kettle holes
basins found on the outwash plain, circular and filled with water
What are eskers
Long ridges of material, going in direction of ice advance
What are kames
Small hills of fluvioglacial deposits
What are some uses of a glacial environment
Sheep farming, scientific research, to live, vegetation, tourists
When was the Antarctic treaty signed
In 1959
What was the purpose of the Antarctic treaty
To establish a zone free of military testing and waste, peaceful purpose only and to promote international scientific cooperation
How many countries signed the Antarctic treaty
56
Why is a wilderness valuable
It’s a habitat for many animals, contains many plants and animals, clean water
Name some scientific research programmes going on in Antarctica
Understanding global change, Life on the edge, understanding how the ice is melting
What is legislation
Agreed rules/regulations, involves international agreements
How are the footpaths affected by tourism in the lakes
Landscape becoming increasingly more damaged due to increased tourism, footpath erosion one of the biggest challenges
What is the water storage in Thirlmere
Man made reservoir, built to supply Manchester with water due to their growing pop in industrial revolution
Why is the reservoir in Thirlmere good
Helped supply Manchester’s growing pop with water, takes water to other places enroute to Manchester, filled by rain and streams
Why is the reservoir in Thirlmere bad
United utilities have to keep watch constantly, people rely heavily on it, constant lorryloads of wood to stop soil erosion in reservoir
