Varves

Part of speech: noun

Definitions

1. A chronological record of sedimentary layers that form in lakes, typically reflecting seasonal changes in the environment
2. A term used in geology to describe annual deposits of sediment, often aiding in understanding past climates
3. Layers of sediment, generally consisting of a light and dark band, deposited in alternating patterns representing annual cycles in lake environments

Etymology: "Varves" is the plural of "varve," a term from geology for the thin, paired layers of sediment laid down in still lakes, typically a pale summer deposit and a dark winter one, so that each pair records a year. The singular was borrowed from Swedish "varv," which means "layer," and in Swedish the word also carries the sense of a turn or revolution, as in one circuit of a rotating object. The Swedish word is the source of the English term, and the English sense is tightly specialised. Geologists adopted it because Swedish and Finnish researchers were the first to study these lake deposits systematically, and the borrowed term kept its plain sense of a layer while narrowing to a single kind of annual sediment. Counting varves is one of the ways scientists date lake records back many thousands of years.