Dating varves
How do you date varves?
Varves can be dated by visual counting and by isotopic methods. X-radiography of sediment cores greatly enhances varve boundaries and facilitates varve counting. Accurate counts are complicated by turbidites, i.e., sediment layers that represent an abrupt event rather than a whole season.
What is a varve of rock?
A varve is an annual layer of sediment or sedimentary rock . The word varve derives from the Swedish word varv whose meanings and connotations include revolution, in layers, and circle. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862.
What is varve chronology and how is it used?
Varve chronology is the use of varve sequences to establish time lines in sedimentary sequences and for correlation.
How accurate is the Swedish varve chronology?
At present, the Swedish varve chronology is based on thousands of sites, and covers 13,200 varve years. In 2008, although varves were considered likely to give similar information to dendrochronology, they were considered too uncertain for use on a long-term timescale.
What is varve dating in geology?
varve dating (geochronology) An absolute dating technique using thin sedimentary layers of clays called varves. The varves, which are particularly common in Scandinavia, have alternate light and dark bands corresponding to winter and summer deposition.
What is varve chronology and how is it used?
Varve chronology is the use of varve sequences to establish time lines in sedimentary sequences and for correlation.
Where does the word varve come from?
The word varve derives from the Swedish word varv whose meanings and connotations include revolution, in layers, and circle. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862.
What is a Varve count?
One varve consists of one light band and one dark band. Varves can be counted to calculate the age of glacial deposits (varve analysis, also called varve chronology or varve count).
What is varve chronology and how is it used?
Varve chronology is the use of varve sequences to establish time lines in sedimentary sequences and for correlation.
Where does the word varve come from?
The word varve derives from the Swedish word varv whose meanings and connotations include revolution, in layers, and circle. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862.
What is a varve layer?
A varve is an annual layer of sediment or sedimentary rock. The word varve derives from the Swedish word varv whose meanings and connotations include revolution, in layers, and circle. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862.
What is the historical record of varved sediments?
Another long record of varved sediments is the palaeo-lacustrine record of the Piànico–Sèllere Basin (southern Alps). Here, the detrital layer part of each varve was used as a proxy for 771 palaeofloods which occurred over a period of 9.3 thousand years during an interglacial period in the Pleistocene.
