A thin layer of fine-grained sediment deposited in the still waters of a lake. Varves are frequently associated with glaciation and represent a yearly sedimentation cycle - a silty, light-colored layer deposited in summer and a darker, organic-rich clay layer deposited during winter.
A pair of sediment beds deposited by a lake on its floor, typically consisting of a thick, coarse, light-colored bed deposited in the summer and a thin, fine-grained, dark-colored bed deposited in the winter. Varves are most often found in lakes that freeze in the winter. The number and nature of varves on the bottom of a lake provide information about the lake's age and geologic events that affected the lake's development.
A pair of thin sedimentary layers, one relatively coarse-grained and light-colored, and the other relatively fine-grained and dark-colored, formed by deposition on a lake bottom during a period of one year. The coarse-grained layer is formed during spring runoff, and the fine-grained layer is formed during the winter when the surface of the lake is frozen.