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Glaciers. Question of the Day. Question: Put the rocks and events in order. Answer: … … …. K. J. I. H. P. M. L. Turn In: Review Sheet Fossil Footprints. N. O. Q. Glaciers . Rivers of Ice. Glacier Facts. Found on every continent- even Africa!
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Question of the Day Question: Put the rocks and events in order. Answer: … … … K J I H P M L • Turn In: • Review Sheet • Fossil Footprints N O Q
Glaciers Rivers of Ice
Glacier Facts • Found on every continent- even Africa! • Cover 10% of the earth’s land area • Contain 75% of the freshwater on earth • Two types: • Alpine (valley glaciers) are found in the mountains • Continental glaciers (ice sheets) are found at the north and south poles
How does a glacier form? • Form when more snow falls than melts in one year • Snow compacts into ice • Ice begins to flow downhill under its own weight
How do glaciers work? • In winter, ice accumulates at the top of the glacier, pushing the glacier downhill • In summer, ice melts at the bottom of the glacier • If the amount that melts in the summer is more than the amount that accumulates in the winter, the glacier retreats Holgate Glacier, Alaska, July 1909 Holgate Glacier, August 2004
Why are retreating Glaciers bad? Qori Kalis Glacier, Peru, July 1978 Qori Kalis Glacier, July 2004 • Glaciers store water and release it later in the year • Snow accumulates in the winter • Melting snow feeds rivers in the summer • Less snow in the winter means less water in the summer • for cities and farming
The size of glaciers relate to sea level • In earth’s past sea level was lower because there were more glaciers • As glaciers melt now, sea level will rise • Could flood coastal cities
Why do geologists care about glaciers? • Glaciers are a force of nature on earth • Glaciers have shaped the landscape that we see now!
Glacial Erosion • As a glacier moves down the side of the mountain, it scrapes off pieces of the surrounding rock • Over time, a large amount of material can be removed by the glacier
Glacial Features: U-Shaped Valleys • When a river erodes a valley, the valley becomes V-shaped • Glaciers are wider than rivers, so they change the shape of the valley • Valley becomes U-shaped
Glacial Features: Sharp Ridges (Aretes) • Two glaciers on two sides of a mountain • When glaciers melt, a sharp ridge remains
Glacial Features: Pyramid Peak (Horn) • A peak where several sharp ridges meet • At least 3 very steep (nearly vertical) sides • Form where several glaciers meet
Glacial Features: Moraines • A pile of rocks that is pushed along as a glacier moves • Can vary in size