Blytt-Sernander sequence

from Wikipedia, the free encyclopedia
series Climate level Pollen zone Period (years BP )
Holocene Subatlantic X 0-2,400
IX
Subboreal VIII 2,400-5,660
Atlantic VII 5,660-9,220
VI
Boreal V 9,220-10,640
Preboreal IV 10,640-11,560
Pleistocene
Younger dryas period III 11,560-12,700
Alleröd Interstadial II 12,700-13,350
Older dryas period Ic 13,350-13,480
Bölling-Interstadial Ib 13,480-13,730
Oldest dryas period Yes 13,780-13,860

The Blytt-Sernander sequence or Blytt-Sernander classification is a series of climatic phases that Northern Europe has passed through over the past 14,000 years. The sequence is based on the analysis of peat bog deposits by the Norwegian Axel Blytt (1876) and the Swede Rutger Sernander (1908). The classification was later incorporated into today's pollen stratigraphy .

method

The development of the classification was preceded by the discovery of lighter and darker layers in peat layers by Heinrich Dau on Zealand in 1829 . As a result, the Royal Danish Academy of Sciences awarded a prize to those who succeed in interpreting these situations plausibly. Blytt then hypothesized that the darker layers were formed in dry periods and lighter layers in wet periods. He used the terms Atlantikum (warm and humid) and Boreal (cold and dry).

In 1908, Rutger Sernander completed the sequence by delimiting the subboreal , the subatlantic and the Pleistocene phases. In 1926, Carl Albert Weber discovered a characteristic borderline horizon in German peat deposits, which supported Blytt's thesis of a climate change.

The purpose of the method was the stratigraphic division of sedimentary deposits , i.e. the division according to their chronological order. Nowadays there is a great variety of different methods for determining age, u. a. Oxygen isotopy , varven chronology or investigations of ice cores. With these newer methods it was possible to extend the Blytt-Sernander sequence to Eurasia and North America. However, the designation Blytt-Sernander sequence is only found comparatively rarely nowadays.

Problems

Dating and calibration

Nowadays the Blytt-Sernander classification is supported and extended by modern research methods. An example is radiocarbon dating ( 14 C dating ) of pollen, by means of which carbon can be dated to about 60,000 years old. However, older dates can be imprecise to a certain extent, as the inconsistent production of cosmogenic 14 Cs was still unknown; rather, it was assumed that production would be constant. To a certain extent, older, less precise dates can be made using other techniques such as B. the dendrochronology can be corrected.

Correlation with archaeological findings

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

The sequence

Pleistocene Duration
Older dryas 14,000-13,600 BP
Allerød-Interstadial 13,600-12,900 BP
Younger dryas 12,900-11,500 BP
Holocene
Boreal 11,500-8,900 BP
Atlantic 8,900-5,700 BP
Subboreal 5,700--2,600 BP
Subatlantic 2,600-0 BP

Pointer plants

Examples of pointer plants or their pollen that play a role in the Blytt-Sernander classification:

Peat mosses are more common in wet periods, birch and pine trees are characteristic of dry periods.

Individual evidence

  1. ↑ T. Litt, A. Brauer, T. Goslar, J. Merkt, K. Balaga, H. Müller, M. Ralska-Jasiewiczowa, M. Stebich, JFW Negendank: Correlation and synchronization of Lateglacial continental sequences in northern central Europe based on annually laminated lacustrine sediments. In: Quaternary Science Reviews. 20, 11, Elsevier, Oxford 2001, pp. 1233-1249.
  2. ↑ I. Faegri, J. Iverson: Textbook of pollen analysis . Copenhagen 1950.
  3. ↑ Heinrich Dau: Allerunterthänigster report to the Royal Danish pension chamber through the peat bogs Zealand after the autumn of 1828, therefore, undertaken trip. (mostly simply over the peat bogs of Zealand. ) Copenhagen / Leipzig 1829.
  4. ↑ Axel Gudbrand Blytt: Essay on the immigration of the Norwegian flora during alternating rainy and dry periods . Cammermeyer, Kristiana 1876.
  5. ^ Rutger Sernander: On the evidence of postglacial changes of climate furnished by the peat mosses of northern Europe . In: Geologiska Föreningens i Stockholm Förhandlingar . tape 30 , 1908, pp. 467-478 ( PDF ).
  6. ↑ Carl Albert Weber: Grenzhorizont and climatic fluctuations. In: Abhandl. Natural science Association, Bremen. 26, 1926, pp. 98-106.

Web links