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Glaciers- Important in understanding global scale climate change

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

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Glaciers- Important in understanding global scale climate change

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  1. 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

  2. Importance • Glacial times represent significant time • Glacial times represent significant time periods in Earth's history periods in Earth's history Proterozoic, Pennsylvanian, Pleistocene • Represent major climatic departures • Represent major climatic departures from the modern on a Global Scale from the modern on a Global Scale • Cyclic in Nature • Cyclic in Nature • Man's Influence??? • Man's Influence??? • Glacial Ice contains records of past • Glacial Ice contains records of atmospheric changes atmospheric changes

  3. Origin of ice

  4. Response of a Glacier to Changes in Glacial Budget If accumulation = ablation, then no advance or retreat, but continues to flow If accumulation > ablation, then glacier advances while flowing If accumulation < ablation, then glacier retreats, but continues to flow

  5. Erosional Processes Erosional Processes ･ ･ Important erosional Important erosional processes associated processes associated with glaciers include with glaciers include plucking, abrasion, and plucking, abrasion, and bulldozing. bulldozing. ･ Plucking and abrasion ･ Plucking and abrasion are most common are most common > can form a landform > can form a landform called a roche called a roche moutonnee moutonnee

  6. Erosional features Roche Moutonnée

  7. Erosional features • Hanging Valley • Horn • Arete • Cirque • U-shaped trough • Col • Truncated Spurs

  8. Glacial Deposits Glacial Deposits • glacial drift- A general term • glacial drift- A general term referring to sediment formed by refering to sediment formed by any Anyglacial action. glacial action. • Till (Diamicton) poorly sorted, • Till (Diamicton) poorly sorted, unlayered material directly unlayered material directly deposited by a glacier; ice contact deposited by a glacier; • Stratified drift (Outwash) sorted, • Stratified drift (Outwash) sorted, layered sediment usually layered sediment usually deposited by meltwater streams. Proglacial or ice contact deposited by meltwater streams.

  9. Depositional features- glacial erratic A glacial erratic 6 ft Yellowstone Park

  10. Sediments- Glacial Till exposed in Iowa

  11. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  12. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  13. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  14. Lateral Lateral moraines moraines Medial Medial moraines moraines ･ ･ Lateral and Medial Lateral and Medial Moraines are sediment Moraines are sediment eroded from the valley eroded from the valley sides and deposited by sides and deposited by a glacier. They often a glacier. They often appear as dark stripes appear as dark stripes in a glacier. in a glacier.

  15. Depositional features- distribution of moraines

  16. Depositional features- Kames, eskers, kettle lakes, drumlins, outwash plain (sandur)

  17. Depositional features- Kames, eskers, kettle lakes, drumlins, outwash plain (sandur)

  18. Outwash with kettles moraine Kame terrace Outwash Kettle lakes

  19. Outwash Plain with eskers and a braided stream

  20. Pleistocene Glaciations Pleistocene Glaciation • The Pleistocene "ice age" began • The Pleistocene "ice age" began ~1.96 million years ago ~1.96 million years ago • Several glacial and interglacial • Several glacial and interglacial Episodes have occurred. episodes. > Glacial - a period of ice advance, generally > Glacial - a period of ice advance, generally interpreted as a globally cool period. interpreted as a globally cool period. > Interglacial - a period of ice retreat, generally > Interglacial - a period of ice retreat, generally interpreted as a globally warm period. interpreted as a globally warm period. We are in an interglacial period right now

  21. Milankovitch Orbital Theory Milankovich Orbital Theory • Proposed to account for the cyclical • Proposed to account for the cyclical nature of Glaciations. nature of Glaciations. • Astronomer & Mathematician Milutin • Astronomer & Mathematician Milutin Milankovitch attributed the glaciation to Milankovich attributed the glaciation to variation in three parameters of the variation in three parameters of the Earth's orbit. Earth's orbit.

  22. Obliquity- not shown eccentricity precession

  23. warm warm cold cold 1 3 4 5

  24. Erie Lobe

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