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

Importance • • 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 Glacial Ice contains records of past atmospheric changes atmospheric changes

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 Erosional Processes ･ ･ 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

Erosional features Roche Moutonnée

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

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

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

Sediments- Glacial Till exposed in Iowa

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 Moraine formation- made of Till, deposited by ice

･ ･ 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.

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 moraine Kame terrace Outwash Kettle lakes

Outwash Plain with eskers and a braided stream

Pleistocene Glaciation Pleistocene Glaciations • • 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. Episodes have occurred. > > Glacial Glacial - a period of ice advance, generally - a period of ice advance, generally interpreted as a globally cool period. interpreted as a globally cool period. > > Interglacial Interglacial - a period of ice retreat, generally - 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

Milankovich Orbital Theory Milankovitch 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 Milankovich attributed the glaciation to Milankovitch attributed the glaciation to variation in three parameters of the variation in three parameters of the Earth's orbit. Earth's orbit.

Obliquity- not shown eccentricity precession

warm warm cold cold 1 3 4 5

Erie Lobe