Post on 30-Dec-2015
description
• Glacier > a mass of ice composed of recrystallizedcompacted snow that flows under its ownweight on land.
• Presently glaciers cover of theEarth's surface.
• Glaciers occur in Greenland andAntarctica and in higher mountainranges.
• Glacier > a mass of ice composed of recrystallizedcompacted snow that flows under its ownweight on land.
• Presently glaciers cover of theEarth's surface.
• Glaciers occur in Greenland andAntarctica and in higher mountainranges.
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Glaciers and Glaciation Glaciers and Glaciation
Glaciers-
Important in understanding global scale climate change
Related to all 5 of the Earth’s systems
Exosphere- changes in the amount of sunlight cause glaciations
Hydrosphere- glacial ice is frozen water, part of the hydrosphere
Geosphere- Glacial ice flows over and modifies land
Atmosphere- alteration of global atmospheric patterns contributes to glacial ice formation
Biosphere- ice displaces animals and plants
Glaciers-
Important in understanding global scale climate change
Related to all 5 of the Earth’s systems
Exosphere- changes in the amount of sunlight cause glaciations
Hydrosphere- glacial ice is frozen water, part of the hydrosphere
Geosphere- Glacial ice flows over and modifies land
Atmosphere- alteration of global atmospheric patterns contributes to glacial ice formation
Biosphere- ice displaces animals and plants
• Glacial times represent significant timeperiods in Earth's history
• Represent major climatic departuresfrom the modern on a Global Scale
• Cyclic in Nature
• Man's Influence???
• Glacial Ice contains records ofatmospheric changes
• Glacial times represent significant timeperiods in Earth's history
• Represent major climatic departuresfrom the modern on a Global Scale
• Cyclic in Nature
• Man's Influence???
• Glacial Ice contains records of past atmospheric changes
Importance
Proterozoic, Pennsylvanian, Pleistocene
• Snowflakes are melted & deformed by the pressure ofoverlying snow, becoming granular snow, then firn, andfinally interlocking crystals of glacial ice.
Origin of ice
Descriptive classification of GlaciersDescriptive classification of Glaciers
• Valley (or Alpine) Glaciers are confinedto mountain valleys.> may eventually cover the entire mountain rangebecoming a mountain ice sheet
> may also spill onto low flatlands becomingPiedmont glaciers
• Continental (or Ice Sheets) > cover vast areas of more than 50,000 km .Today, continental glaciers are only found inGreenland and Antarctica.
> Not so in the geological past
• Valley (or Alpine) Glaciers are confinedto mountain valleys.> may eventually cover the entire mountain rangebecoming a mountain ice sheet
> may also spill onto low flatlands becomingPiedmont glaciers
• Continental (or Ice Sheets) > cover vast areas of more than 50,000 km .Today, continental glaciers are only found inGreenland and Antarctica.
> Not so in the geological past
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Response of a Glacier to Changes in Glacial BudgetIf accumulation = ablation, then no advance or retreat, but continues to flowIf accumulation > ablation, then glacier advances while flowingIf accumulation < ablation, then glacier retreats, but continues to flow
Effects of GlaciersEffects of Glaciers
• Fills in the low spots> valleys and basins get filled in w/ sediment
• Knocks down the high spots> mountains and hills get eroded
• Reroutes the drainages> valley filling may block streams, causingnew paths to be taken
• Deposits accumulate in specificplaces related to flow and meltwatercharacteristics
• Fills in the low spots> valleys and basins get filled in w/ sediment
• Knocks down the high spots> mountains and hills get eroded
• Reroutes the drainages> valley filling may block streams, causingnew paths to be taken
• Deposits accumulate in specificplaces related to flow and meltwatercharacteristics
Erosional ProcessesErosional Processes
･ Important erosionalprocesses associatedwith glaciers includeplucking, abrasion, andbulldozing.
･ Plucking and abrasionare most common> can form a landformcalled a rochemoutonnee
･ Important erosionalprocesses associatedwith glaciers includeplucking, abrasion, andbulldozing.
･ Plucking and abrasionare most common> can form a landformcalled a rochemoutonnee
Erosional features•Hanging Valley•Horn•Arete•Cirque•U-shaped trough•Col•Truncated Spurs
Erosional features•Hanging Valley•Horn•Arete•Cirque•U-shaped trough•Col•Truncated Spurs
Glacial DepositsGlacial Deposits• glacial drift- A general termrefering to sediment formed by anyglacial action.
• Till (Diamicton) poorly sorted,unlayered material directly
deposited by a glacier;• Stratified drift (Outwash) sorted,layered sediment usuallydeposited by meltwater streams.
• glacial drift- A general termreferring to sediment formed byAny glacial action.
• Till (Diamicton) poorly sorted,unlayered material directlydeposited by a glacier; ice contact
• Stratified drift (Outwash) sorted,layered sediment usuallydeposited by meltwater streams.Proglacial or ice contact
･ Lateral and MedialMoraines are sedimenteroded from the valleysides and deposited bya glacier. They oftenappear as dark stripesin a glacier.
･ Lateral and MedialMoraines are sedimenteroded from the valleysides and deposited bya glacier. They oftenappear as dark stripesin a glacier.
LateralmorainesLateralmoraines
Medial morainesMedial moraines
Outwash with kettles
Kettle lakesKettle lakes
OutwashOutwash
morainemoraine
Kame terraceKame terrace
Pleistocene GlaciationPleistocene Glaciations
• The Pleistocene "ice age" began~1.96 million years ago • Several glacial and interglacialepisodes.> Glacial - a period of ice advance, generallyinterpreted as a globally cool period.
> Interglacial - a period of ice retreat, generallyinterpreted as a globally warm period.
• The Pleistocene "ice age" began~1.96 million years ago • Several glacial and interglacialEpisodes have occurred.> Glacial - a period of ice advance, generallyinterpreted as a globally cool period.
> Interglacial - a period of ice retreat, generallyinterpreted as a globally warm period.
We are in an interglacial period right now
Milankovich Orbital Theory Milankovitch Orbital Theory • Proposed to account for the cyclicalnature of Glaciations.
• Astronomer & Mathematician MilutinMilankovich attributed the glaciation tovariation in three parameters of theEarth's orbit.
• Proposed to account for the cyclicalnature of Glaciations.
• Astronomer & Mathematician MilutinMilankovitch attributed the glaciation tovariation in three parameters of theEarth's orbit.