varve

/vɑːrv/
noun
  1. A pair of thin layers of sediment deposited in a lake or other body of water over the course of one year, used by scientists to study past climates.
    • Each varve contains a light summer layer and a dark winter layer.
    • By counting varves, researchers can determine the age of sediment layers very precisely.
    • Geologists examined a varve from an ancient lake bed to learn about the climate thousands of years ago.
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