Blytt–Sernander system

The Blytt - Sernander sequence or Blytt - Sernander classification is a series of climatic phases that Northern Europe has undergone in the last 14,000 years. The sequence is based on the analysis of Torfmoorablagerungen by the Norwegian Axel Blytt (1876 ) and Sweden Rutger Sernander (1908 ). The classification was later incorporated into the now common Pollenstratigraphie.

Method

The development of classification was the discovery of lighter and darker layers in peat in 1829 by Heinrich Dau on Zealand ahead. Afterwards, a price has been awarded by the Royal Danish Academy of Sciences, with the one who should be considered, which would succeed to interpret these documents plausible. Blytt responded by imposing the hypothesis that the darker layers in dry periods and lighter layers were formed in wet periods. That purpose he used the terms Atlantikum (hot and humid ) and Boreal ( cold and dry).

In 1926, Carl Albert Weber a characteristic boundary horizon in German peat deposits that supported Blytts thesis of climate turnaround. Rutger Sernander completed the sequence by the narrowing of the Sub-boreal, the Subatlantikums and the Pleistocene phases.

The purpose of the method was the stratigraphic classification of sedimentary deposits, so the subdivision according to their chronological order. Nowadays there are a wide variety of different methods to determine the age, including oxygen isotopic composition, Warvenchronologie or studies of ice cores. By means of these newer methods it was possible to extend the Blytt - serander sequence to Eurasia and North America. However, the term Blytt - Sernander sequence is nowadays only comparatively rare.

Problems

Dating and calibration

Nowadays Blytt - Sernander classification is supported by modern research methods and expanded. As an example, the radiocarbon dating of pollen may be mentioned, by means of which can be dated to about 60,000 year old carbon. In this case, older dating, however to a certain extent be imprecise because the erratic production cosmogenic C- 14s was still unknown; Rather, it was based on a constant production. Up to a certain extent, older, less precise dating can also be such as dendrochronology, corrected by other techniques.

Correlation with archaeological evidence

The Blytt - Sernander classification has been and is used as a chronological framework to interpret archaeological findings in North America and Eurasia. So some technical changes are directly associated with climate variability, but this is not without controversy.

The sequence

Indicator plants

Examples of indicator plants and their pollen, which play a role in the Blytt - Sernander classification:

• Sphagnum ( peat moss )
• Carex ( sedge )
• Scheuchzeria palustris (flowers rushes )
• Eriophorum vaginatum ( vaginal cotton grass )
• Vaccinium subgenus oxycoccus ( Cranberries )
• Andromeda polifolia ( rosemary )
• Erica tetralix ( bell heather )
• Calluna vulgaris ( heather )
• Pinus ( pine )
• Betula ( birch )

Peat mosses are common in wet periods for droughts birch and pine are characteristic.