Lecture 32 (Friday, April 12): Glaciers and Glaciation II: Continental Glaciation
Brief outline of this lecture:
Main points of this lecture:
Continental glaciation involves thicker and broader masses of ice than alpine glaciation.
The weight of the ice on Greenland and Antarctica has depressed the solid land (rock) surface down to about sea level.
The Quaternary Period (the last two million years) has been characterized by extensive continental glaciation.
Continental glaciation extended across North America in the Quaternary southward to roughly the Ohio and Missouri rivers.
Quaternary glaciation has involved repeated advances and retreats of continental glaciation, with a periodicity of abbout 100,000 years.
Advances of glaciers resulted in lowering of sea level by 50 to 100 meters; retreats of glaciers resulted in rises of sea level.
Within that series of advances and retreats, or glacial and interglacial intervals, the last 10,000 years have been just another interglacial interval.
Prior to present concerns about global warming, scientists assumed the Earth would return to a glacial interval in the next ten thousand years or so.
Figures used in this lecture:
Cross-section of continental glaciation
Patterns of glacial ice flow
Erosional features of continental glaciation
Depositional features of continental glaciation
An esker now, and then
Reading assignment: Pages 207 to 211 and Glacial Processes.
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