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:

Rivers of Ice

Glacier FactsFound on every continent- even Africa!Cover 10% of the earth’s land areaContain 75% of the freshwater on earthTwo 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

yearSnow compacts into iceIce 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 downhillIn 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

Retreating Glaciers and Global Warming

Holgate Glacier, Alaska, July 1909

Holgate Glacier, August 2004

Retreating Glaciers and Global Warming

Qori Kalis Glacier, Peru, July 1978

Qori Kalis Glacier, July 2004

How are glaciers affected by global warming?All glaciers are getting smaller every year!!Sea level is rising…coastal cities could flood!

Why do geologists care about glaciers?Glaciers have shaped the landscape that we

see now!

Glacial Landscapes

Yosemite Valley, Yosemite National Park, CA

Glacier National Park, Montana

The Matterhorn, Switzerland- Italy Border

Glacial ErosionAs 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 ValleysWhen a river erodes a valley, the valleybecomes V-shaped Glaciers are wider than rivers, so theychange the shape of the valleyValley becomes U-shaped

Glacial Features: Sharp Ridges (Aretes)Two glaciers on two sides of a mountainWhen glaciers melt, a sharp ridge remains

Glacial Features: Pyramid Peak (Horn)A peak where several sharp ridges meetAt least 3 very steep (nearly vertical) sides Form where several glaciers meet

CitationsLonnie G. Thompson, Byrd Polar Research

Center, the Ohio State University