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The Ice Age

The Ice Age. How it happened Ice age evidence Causes of g lacial climates. The Ice Age.

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The Ice Age

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  1. The Ice Age How it happened Ice age evidence Causes of glacial climates

  2. The Ice Age • An "ice age" or "glacial age" is a period of long-term reduction in the temperature of the Earth’s surface and atmosphere, resulting in the presence/expansion of continental glaciers, ice caps and alpine glaciers • Within an ice age; pulses of extra cold climate are termed glacial periods • Intermittent warm periods are called interglacials. • Ice age implies the presence of extensive ice in the northern and southern hemispheres • By this definition we are still in the ice age that began at the start of the Pleistocene

  3. The Ice Sheets: • Video • Retreated 11,000 years ago • The maximum extent of glaciation was approximately 18,000 years ago • The last glacial period was from approximately 110,000 to 10,000 years ago • During this period there were several changes between glacier advance and retreat • We are currently in an interglacial period • Three centers where the ice was thickest: • Labrador center east of Hudson Bay • Keewatin center west of Hudson Bay • Cordilleran center in the Canadian Rockies

  4. Glacial, Interglacial Periods?

  5. Glacial features: • Terminal moraines • Outwash plains • Drift (Till and Outwash) • Stratified and polished exposed bedrock • North-south valleys are shaped into glacial troughs • East-west valleys partly filled with drift • Kames, eskers, drumlins, and glacial lakes Ice age Evidence:

  6. Glacial Climate Facts: • Lets consider certain facts: • This Ice Age began about 1 million years ago, and included major advances in the ice sheets. • Warm interglacial periods came after each advance, we are currently in an interglacial period. • Other ice ages have occurred in the past 600 million years. • During the last ice age, glaciers advanced and receded at the same time in both the Northern and Southern hemispheres.

  7. Hypotheses: all have strong and weak points • The amount of heat given off by the sun changes • The amount of energy reaching Earth might change due to volcanic dust in the atmosphere • During periods of mountain building, more of Earth’s landmass is above the snowline • The position of continents were different, impeding currents between oceans and preventing mixing of cold and warm water • Changes in the tilt of Earth’s axis and in the shape of its orbit

  8. An Inconvenient Truth: • Al Gore “tries to point this nation in a direction that isn’t just about money, greed, oil, and getting more stuff to fill up a McMansion. It’s about the fragility of the earth. It’s about finding solace in duty, ethics, and the future. We can turn an inconvenient truth into a cause for celebration by acting locally to create global results.” • http://www.webomatica.com/wordpress/2006/06/21/movie-notes-an-inconvenient-truth/

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