Varves

First published: 1999

Brief summary

Reference on annually laminated sediments recording seasonal cycles.

Article

A varve is an annual layer of sediment deposited in a lake or other quiet-water environment. Varves commonly form where seasonal changes produce contrasting sediment types during different parts of the year.

In glacial lakes, summer meltwater can carry relatively coarse silt and sand into the basin, while winter ice cover and reduced inflow allow fine clay to settle. The resulting light and dark layers together represent one year of deposition.

Counting varves can establish a year-by-year chronology, while layer thickness, grain size, organic content and geochemistry can record changes in meltwater discharge, rainfall, temperature, productivity and sediment supply.

Varve chronologies can provide high-resolution records of environmental change, but accurate interpretation requires confirmation that each couplet is annual. Erosion, slumping, missing layers and multiple depositional events within a year can complicate counting and correlation.

Source details and credits

• Source / publisher: Britannica
• Source type: Reference article
• URL type: WWW
• Credits: Britannica
• URL: https://www.britannica.com/science/varve