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

Origin of ice

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

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

Erosional features Roche Moutonnée Erosional features Roche Moutonnée

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

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

Sediments- Glacial Till exposed in Iowa Sediments- Glacial Till exposed in Iowa

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

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

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

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

Depositional features- distribution of moraines

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

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

Outwash with kettles Kettle lakes Outwash moraine Kame terrace

Outwash Plain with eskers and a braided stream

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

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

eccentricity precession Obliquity- not shown

warm cold 1 354

Erie Lobe