ˈvärv, ˈvȧv noun
( -s )
Etymology: Swedish varv turn, revolution, layer; akin to Old English hweorfan to turn — more at wharf
: a pair of layers of alternately finer and coarser silt or clay believed to comprise an annual cycle of deposition in a body of still water (as a glacial lake) and used to measure the time involved in the deposition of the entire group of sediments and to construct a time scale in a manner similar to that employed in the study of annual rings in trees
varve chronology