varve

varve, in geology, pair of thin sedimentary layers formed annually by seasonal climatic changes. Usually found in glacial lake deposits, varves consist of a coarse-grained, light-colored summer deposit and a finer-grained, dark-colored winter deposit formed when fine sediment settles out from the water under the ice cover. Varves, and the pollen they contain, are useful for interpreting recent climatic history.

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