A varve is a pair of sedimentary layers deposited annually, consisting of a light-colored layer of coarse particles deposited in the summer and a dark-colored layer of fine particles in the winter. Varves are significant in paleoclimatology and geology for studying past environmental conditions, dating sedimentary sequences, and reconstructing historical climate change.
Source Ojala, A. E. K. (2001). “Varved Lake Sediments in Southern and Central Finland: Long Climate Records and Holocene Palaeoenvironmental History.” Boreal Environment Research, 6, 25-47.