glaciation

inputs

energy from the sun, precipitation, rock debris

outputs

meltwater, sediment deposition

transfers

erosion and transportation processes, which move ice and rock around the system

Steady-state equilibrium

changes in accumulation and ablation do not vary much from the long-term average conditions

metastable equilibrium

the glacier changes from one state of equilibrium to another due to an event causing a change in conditions

dynamic equilibrium

the state of equilibrium changes over a longer timescale than metastable equilibrium

positive feedback

increases the initial change: e.g
increase in snoww cover --> more solar energy, reflected, creating cooler temperatures --> more snow

negative feedback

global warming increases evaporation and cloud cover --> more solar energy is reflected, creating cooler temperatures

eccentricity

elliptical orbit changes to more circular and back again over a 100,000 years, varying the amount of solar radiation reaching earth

axis tilt

varying from 21.8 to 24.4 over a period of 41,000 years, changing the amount of solar radiation at the poles

wobble

earth wobbles on its axis over a 20,000 year cycle, changing the time of year when it is closet to the sun

pleistocene (Quaternary period)

2.5 million - 11,500 years ago,

holocene (Quaternary period)

11,500 years ago to today, which is the present interglacial period

little ice age

glacial oscillation between 1350 and 1850

cold based glaciers

- occur in high latitudes
- ice temperature below pressure melting point
- basal ice is frozen to bedrock
- most movement by internal deformation
- little erosion due to lack of movement

warm based glaciers

- occur in temperate regions
- temperature at base at pressure melting point
- heat from earth adds to melting
- meltwater assists movement of glacier
- actively eroding and transporting

polythermal glaciers

cold-based in the upper region and warm-based lower down

shear stress

the downslope force due to gravity resulting from the build-up of an ice mass

internal deformation

intergranular flow - under pressure the ice crystals move relative to each other

laminar flow - ice crystals move along parallel layers within the glacier

basal sliding

enhanced basal creep - basal ice deforms around irregularities in the bedrock surface

regelation slip - basal ice deforms under pressure caused by obstacles; once past the obstacle the meltwater refreezes

subglacial bed deformation

softer rock and unconsolidated sediments are not strong, so the weight of the ice in a glacier can cause the sediments to deform. As the sediments change shape, the ice on top moves with them

compressional flow

a reduction in gradient results in a slowing of movement. The ice thickens, crevasses close and thrust faults develop in the ice

extensional flow

an increase in gradient results in accelerated movement. The ice thins and crevasses form

ice sheet

an ice dome, several kilometres thick, submerging the topography beneath

ice shelf

a large area of floating glacier ice extending from the coast

ice cap

a smaller version of an ice sheet covering an upland area

ice field

ice covering an upland area, but not burying topography

valley glacier

a glacier confined between valley sides

Piedmont glacier

a valley glacier that fans out over a flatter area at the end of the valley

cirque glacier

a small glacier filling a hollow on the side of a mountain

distribution of ice cover

today - 10% of earth's land area
85% of all glaciers are in Antarctica

freeze-thaw

repeated freezing and thawing of water, expanding cracks in rocks and eventually causing fragments to break off and fall on to the glacier

abrasion

debris embedded in the glacier base scrapes the bedrock as it moves

plucking

ice freezing on to valley sides, floor and bedrock pulls away rocks as it moves

subglacial fluvial erosion

meltwater flowing at the base of a glacier erodes rock the same way as surface streams. Pressure causes streams to flow faster, increasing erosion potential

factors affecting glacial erosion

- basal thermal regime
- ice velocity
- ice thickness
- bedrock permeability
- bedrock jointing
- debris characteristics

supra glacial

debris from weathering falls from valley sides onto the glacier

englacial

debris falls into crevasses and is moved within the glacier

subglacial

basal ice freezes around material and drags it along by traction. Englacial material moving to the base and plucking adds to the amount

ablation till

unsorted, angular material deposited by melting ice. Stones show no preferred orientation

lodgement till

rounded, subglacial material deposited by a moving glacier. The long axis of stones is orientated in the direction of movement

deformation till

weak bedrock is deformed by ice movement

terminal moraine

a high ridge across a valley deposited as a glacier retreats from the furthest point reached

recessional moraine

a series of ridges across a valley behind a terminal moraine, marking a stationary period in ice retreat

lateral moraine

weathered material falls on to a glacier from valley sides. When the ice melts it deposits a ridge parallel to the valley sides

medial moraine

two lateral moraines combine along the centre of glacier surface when valley glaciers merge. As ice melts it is deposited along the middle of the valley

push moraine

when glaciers begin advancing again, the debris at the snout is pushed into a ridge

erosion - fluvioglacial processes

subglacial streams are under pressure and fast flowing, eroding bedrock especially by abrasion

transportation - fluvioglacial processes

high-energy meltwater streams have the capacity to transport large sediment loads

deposition - fluvioglacial processes

when I loses energy it deposits material; rounder than glacial deposits, sorted by size, distinct layers

periglacial

the edges of glacial areas, where repeated freezing and thawing modify the landscape

permafrost

soil and rock that is below O degrees celsius for at least 2 years

continuous permafrost

a.layer of frozen ground that can be hundreds of metres deep

discontinuous permafrost

a thinner, fragmented layer of frozen ground

sporadic permafrost

an isolated mass of permafrost in unfrozen ground

active layer

the surface layer up to 3m deep, which thaws in summer and refreezes during the winter

pingos

a dome-shaped mound of earth up to 70m high and 500m in diameter, with an ice core

mass movement

the downward movement of materials due to gravity

rapid mass movement

rockfalls and landslides change the profile fo a glacial valley

rapid glacier melt

volcanic activity causes large-scale melting, resulting in flooding and rapid mudflows

Arête example

Helvellyn range

corrie/tarn example

red tarn

U shaped valley example

Ullswater valley

Ribbon lake example

Ullswater

Roché mountonnée example

Norfolk island

Truncated spur example

Walla crag

What countries were in the alpine convention 1995

8 countries
- France
- Switzerland
- Liechtenstein
- Italy
- Slovenia
- Austria
- Germany
- Monaco

what are the 8 protocols of the Alpine convention

- mountain farming
- energy
- mountain forests
- conservation of nature + countryside
- Transport
- Tourism
- soil conservation
- spacial planning and sustainable development

Hohe Tauern - Austria

- largest protected area in alps
- Grossglockner glacier --> 3000m
- 4000 types of fungi
- 20,000 animal species

What is done to make Hohe Tauern sustainable

- donation of land use
footpaths well maintained
- Gardonna Mountain Resort --> eco hotel
- public transport = free
- protection of ski areas --> cow's graze in summer

GLOF

glacial lake outburst flood

impacts of GLOF's

affects fresh water, agriculture, livelihood

GLOF case study = Dig Tsho (Butan - 1994)

- increase in depth due to melting ice caused moraine dam to break
- village flooded 7 hours after dam break
- 2m deep, 200km away from source