191 In general, white layers in a glacier represent a time when ice accumulated and little melted. Dark areas represent a time when much ice melted, causing the rock material to become concentrated. The resulting light/dark layers are indicators of seasonal and climatic changes.

Annual layers in glacial ice, Alaska. The light colored layers in this image represent the time or season of accumulation (snowfall); dark layers of sand and silt represent the season of melting and ice exposure. A light layer/dark layer combination equals one year.

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