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Unformatted text preview: Glacial Effects on Coasts I. Causes 5°C drop in Global Temperature Continents in Polar Regions Why important? Milankovitch Cycles-caused by Perturbations of Earth’s orbit around the Sun Milankovitch Serbian Mathematician Milankovitch Cycles How circular is the orbit How much is Earth tilted on its axis Precession of Earth’s axis Glacial Effects on Coasts
Temperature Carbon dioxide Dust 1. Eccentricity How Circular versus Elliptical the Earth’s orbit around the Sun is Periodicity 96,000 years 2. Obliquity
NP Amount of Tilt of the Earth’s Axis of Rotation from Vertical Varies 21.8°- 24.4°, Affects seasonality The Greater the tilt, the greater the severity of summeSPand winter r se Periodicity ~ 41,000 years 3. Precession Circular precession of the axis of rotation Periodicity 23,000 years Present axis of rotation points to the North Star In 11,500 years Axis will point towards Vega, summers will be hotter and winters will be colder in No. Hemisphere Glacial Effects on Coasts
Temperature Carbon dioxide Dust Present Situation Sun’s direct rays over the Tropic of Cancer If the tilt angle is Greater, the Sun’s direct rays occur North of the Tropic of Cancer As the tilt increases, our summers get Warmer and winters get Colder 23.5 ° II. Growth of the Ice Sheets
Greenland Greenland, Antarctica Arctic ice cap is Floating Ice Sheets Grow when:
1. more precipitation during winter 2. less ice melting during summer Ice sheets flow due to pressure deformation ~50m thick
Antarctica III. Direct Effects of Glaciation
A. Erosional Processes: 1. Ice Sheets strip away sediment cover to bedrock - Ice Sheets Antarctica, Greenland - during Pleistocene (Ice Age) - ice sheet emanated from Hudson Bay Laurentide Ice Sheet Covered New England extended to Long Island, Nantucket, and Martha’s Viineyard V 2.. Alpine Glaciers concentrated erosion in mountain 2 valleys Fjord Laurentide Ice Sheet
E m a n a te d f r o m H u d s o n B a y Hudson Bay III. Direct Effects of Glaciation
A. Erosional Processes of Continental Glaciers: 1. Ice Sheets strip away sediment cover to bedrock - rocky coast of Maine - bedrock islands - few beaches fe Coast of Maine 2. Valley Glaciers Alpine Glaciers Flow through existing mountain valleys Excavation of bedrock leads to deepening of valleys In Coastal Mountain Settings -Deepened valleys are flooded when glaciers retreat flooded valley Fjord ...
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This note was uploaded on 04/14/2011 for the course GEO 142 taught by Professor Fitzgereld during the Spring '11 term at BU.
- Spring '11