Blytt-Sernander sequence
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:
- Sphagnum (peat moss)
- Carex (sedges)
- Scheuchzeria palustris (rushes)
- Eriophorum vaginatum (vaginal cottongrass)
- Vaccinium subgenus oxycoccus (cranberries)
- Andromeda polifolia (rosemary heather)
- Erica tetralix (bell heather)
- Calluna vulgaris (common heather )
- Pinus (pine)
- Betula (birch trees)
Peat mosses are more common in wet periods, birch and pine trees are characteristic of dry periods.
Individual evidence
- ↑ 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.
- ↑ I. Faegri, J. Iverson: Textbook of pollen analysis . Copenhagen 1950.
- ↑ 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.
- ↑ Axel Gudbrand Blytt: Essay on the immigration of the Norwegian flora during alternating rainy and dry periods . Cammermeyer, Kristiana 1876.
- ^ 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 ).
- ↑ Carl Albert Weber: Grenzhorizont and climatic fluctuations. In: Abhandl. Natural science Association, Bremen. 26, 1926, pp. 98-106.