Dating glacier layers
The term “varve sequence” is used as a generic term to refer to any succession of varves regardless of whether they are single outcrop records or represent larger, more regional correlations involving many varve records.
Varve record: A measured string of varves from a single exposure or drill core.
To use a varve sequence to establish the true or calendar ages of events it is necessary to calibrate the sequence with numerical ages.
The technique which has been used most frequently to do this in glacial varve sequences is radiocarbon (C) dating.
Note: It has become customary in varve measurement and in the development of varve records, series, and chronologies to number varves in the order in which they were deposited from oldest (lowest number) to youngest (highest number).
In glacial environments varve sequences are used to establish time lines for such things as deglaciation or the repopulation of regions by organisms following deglaciation.
A data file and the lines posted on the image were all created by a computer program designed to sequentially measure varve sequences.
The pattern shown on the plot, or varve record, should be distinctive of the time during which the varves were deposited.
Varve chronology is the use of varve sequences to establish time lines in sedimentary sequences and for correlation.Red lines represent the bottoms of summer layers and blue lines mark the bottoms of winter layers.