Image Description from historic lecture booklet: "When the amount of ice developed form snow becomes great enough, it begins to move out by a sort of spreading motion from the place where it was formed. When it begins to move, it becomes a glacier. Not all snow-fields give rise to glaciers, but all glaciers have their sources in snow-fields.

For convenience of reference the glaciers now known may be arranged in three classes, alpine, piedmont, and continental. These three classes are not always distinct and clearly separable, but typical examples of each may be selected that are well characterized, and differ in essential features from typical examples of each of the other classes. In each group there are conspicuous variations which suggest minor or more specific subdivisions."

Original Collection: Visual Instruction Department Lantern Slides

Item Number: P217:set 012 003

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