KEY POINTS IN THIS CHAPTER •
Glaciers can be large sheets on major continents or sit in valleys as alpine glaciers.
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Glacial ice is layered and comes from packed snow that persists year after year.
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Glaciers move internally as well as downhill on melted water slides beneath them.
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Glaciers have depositional and erosional features.
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Glacial erosion can create polished areas of rock and U-shaped valleys.
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Deposition of glaciers leads to till. Till can be very fine or as large as erratics left behind as glaciers retreat.
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Glacial lakes are often very large. The current five great lakes in the US Midwest are proglacial lakes from the last great ice age.
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