1. Rivers of Ice

2. 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

3. 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

4. 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

5. Retreating Glaciers and Global Warming Holgate Glacier, Alaska, July 1909 Holgate Glacier, August 2004

6. Retreating Glaciers and Global Warming Qori Kalis Glacier, Peru, July 1978 Qori Kalis Glacier, July 2004

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

8. Why do geologists care about glaciers? Glaciers have shaped the landscape that we see now!

9. Glacial Landscapes Yosemite Valley, Yosemite National Park, CA Glacier National Park, Montana The Matterhorn, Switzerland- Italy Border

10. 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

11. 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

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

13. 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

14. Citations Lonnie G. Thompson, Byrd Polar Research Center, the Ohio State University