What is Varve?
[[File:1706141 xpl 20x.tif|thumb|right|A [[photography|photograph]] taken under a [[microscope]] shows varved [[clay]]. The [[Scale (ratio)|scale bar]] of 1 [[millimetre]] shows how much the photograph is enlarged.]] A '''varve''' is a pattern in [[sediment]] which is made by [[wikt:annual|annual]] processes (deposits which vary during the year). Varves are amongst the smallest-scale events in [[stratigraphy]]. They form only in fresh or [[brackish water]]. Varves are important in [[palynology]], and can be fossilized as [[rhythmite]]s. The classic varve [[archetype]] is a light/dark-coloured couplet deposited in a [[glacial lake]]. The light layer is usually [[silt]] and fine [[sand]] deposited when [[Spring (season)|spring]] meltwater brings sediment into the lake. During winter, when meltwater and its sediment is reduced and the lake surface freezes, fine [[clay]]-size sediment is deposited forming a dark-coloured layer. Varve formation needs the absence of [[bioturbation]] (lake bottom disturbed by animals). Therefore, varves usually form under [[anoxic]] conditions. {{Rock type}} {{stub}} [[Category:Geology]]