Preboreal

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series Climate level Pollen
zone 		Period
Holocene Subatlantic X 450 BC Until today
IX
Subboreal VIII 3,710-450 BC Chr.
Atlantic VII 7,270-3,710 BC Chr.
VI
Boreal V 8,690-7,270 BC Chr.
Preboreal IV 9,610-8,690 BC Chr.
Pleistocene
Younger dryas period III 10,730-9,700 ± 99 BC Chr.

The preboreal (also: preheating period ) is the oldest period of the Holocene in geological history . It lasted from 11,560 to 10,640 cal vh , which corresponds to 9610 to 8690 BC. Chr.

Definition of terms and stratigraphic position

The term preboreal (i.e. in front of the boreal) is derived from the Latin pre - vor, vor and the Greek god of the north wind Βορέας - boreas.

The preboreal followed the subarctic period of the Younger Dryas (10,850 to 9610 BC) with their treeless tundras . It was in turn replaced by the Boreal .

The preboreal corresponds to the pollen zone IV by Franz Firbas (1949) or the pollen zone I by WH Zagwijn (1986) and by Litt et al. (2001).

In terms of climatic stratigraphy, the preboreal can be divided into three parts (from young to old):

According to this threefolding, W. Z. Hoek (1997) differentiates between the three pollen zones 4a (Friesland phase), 4b (Rammelbeek phase) and 4c (late preboreal).

Investigations of Russian peatlands divide the preboreal into a PB-1 (10,000 to 9800 radiocarbon years or 9600 to 9270 BC) and a PB-2 (9800 to 9300 radiocarbon years or 9270 to 8541 BC).

The preboreal and the boreal form the Old Holocene .

In terms of cultural history, the preboreal corresponds to the beginning of the Mesolithic .

Chronological order

Mesolithikum Neolithikum Bronzezeit Eisenzeit Yoldia-Meer Ancylussee Littorinameer Boreal (Klimastufe) Subatlantikum

Note: Only the borders marked with a black dividing line are more or less exact; they are based on annual layers in lake sediments in north-central Europe and, strictly speaking, only apply to the climatic stages. The other boundaries are uncertain and not rigidly set. In particular, the boundary between the Middle and Young Holocene is very variable. Regarding the cultural levels, the regionally different development must be taken into account.

Dating

The beginning of the Holocene and thus of the Preboreal is usually with the period 9700 to 9610 BC. Chr. Indicated. In a recalibration, the period 9530 to 9500 BC is also included. Envisaged. The end of the preboreal comes at 8690 BC. To lie.

Climate history

The temperature curve in the Holocene

At the beginning of the Friesland phase , the average temperatures in the northern hemisphere rose extremely quickly: by six degrees Celsius in just 20 to 40 years. The rise in temperature mainly affected the average winter temperatures; Bos u. a. (2007) based on plant communities only an increase of up to 3 ° C. Comparably sharp increases in temperature had already occurred several times towards the end of the Vistula Ice Age ( Dansgaard-Oeschger events ).

The preboreal fluctuation brought about from 9350 BC. A sudden deterioration in the climate, from 9300 BC Chr. Then largely moist, wet and cold conditions established themselves. Towards the end of the preboreal fluctuations, the climate recovered suddenly and the temperatures rose again by 4 ± 1.5 ° C.

During the late preboreal, temperatures remained roughly at their level with slight fluctuations, from 8900 BC. However, there was an increasing tendency towards the Boreal.

Environmental parameters

Greenhouse gas carbon dioxide

The carbon dioxide concentration was towards the end of Friesland phase of around 260 ppmv soared to 330 ppmv in the air. It showed no significant change during the Rammelbeek phase. In the late preboreal, it initially fell again to 300 ppmv, and then leveled off at the already quite high value of 350 ppmv.

Oxygen isotopes

The δ 18 O values indicate the beginning of the Friesland-phase parallel to a dramatic increase in temperature profile to 5 ‰ of - 41 ‰ to - 36% ( SMOW ). During the cool Rammelbeek phase, they drop by 3 ‰. After rising again at the beginning of the late preboreal, they finally stabilize at -37 ‰ (SMOW).

Radiocarbon

The Δ 14 C values show no significant fluctuations during the early preboreal. After a slight increase at the beginning of the Friesland phase to - 5 ‰, however, the trend is towards more negative values ​​around - 20 ‰. During the Rammelbeek phase, stabilization occurs at - 22 ‰. At the beginning of the late preboreal there is a rapid increase from - 15 ‰ to positive values ​​with a maximum of 15 ‰ by 9000 BC. At the exit of the preboreal ten per thousand are then registered.

Development of vegetation history

Birch , pine and hazel trees spread further north from southern refuges (e.g. Upper Rhine Plain, Rhone Valley, Middle Danube), and birch or birch-pine forests emerged. The rapid spread of the hazel, but mainly from the beginning of the Boreal, is associated with the immigration of humans. The predominant taxon in the preboreal forest was the birch ( Betula pubescens and Betula pendula ), which was only displaced by the pine towards the end of the late preboreal. Accompanying plants were mountain ash ( Sorbus aucuparia ) and aspen ( Populus tremula ), as well as the heat-sensitive juniper species Juniperus communis and Juniperus nana .

The birch had grown in importance very quickly during the Friesland phase, but had declined sharply during the cool preboreal fluctuation. The heather-like (Ericales) disappeared at the beginning of the preboreal and herbal plants of higher locations were generally in decline. Open grasslands with sweet grasses (Poaceae) were temporarily able to re-establish themselves during the preboreal fluctuation.

The pre-boreal is followed in the boreal by the immigration of mixed oak forests in Central Europe, which preferably consisted of oak , elm , linden and ash .

Sea level

The postglacial sea level rise

The rise in sea level during the preboreal was around 9 meters (from 63 meters below sea ​​level to 54 meters below sea level). However, it was not homogeneous, rather the rate was up to 9100 BC. BC still relatively low (5 millimeters / year), only to pick up strongly in the late preboreal (15 millimeters / year).

Baltic region

The preboreal in the Baltic Sea region is shaped by the development of the Baltic ice reservoir , which drains over the Öresund and which was formed around 10,600 BC after the Fennoscan ice sheet had melted. Was created before the beginning of the preboreal. Around 9200 BC The ice reservoir was lowered by five to ten meters due to the formation of a new outflow near Billingen in central Sweden . This discharge was found around 8800 BC. Bounded by an ice advance, whereupon the water level in the ice reservoir rose again. The ice reservoir remained until the early Boreal (8300 BC).

Cultural and historical development

The early Mesolithic correlates with the preboreal, but its beginning sometimes only dates back to 9000 BC. Is set. Carrier cultures are the Beuronia in southern Germany (9600 to 7000 BC), the Maglemose culture from 9000 BC. In Denmark and the Creswellia in England (12,500 to 8,000 BC). In Belgium , the Neerharen Group , the Ourlaine Group and the Verrebroek Group should be mentioned. The Haltern level in North Rhine-Westphalia did not begin until the Boreal (from 7400 BC).

The Epipalaeolithic (12,000 to 9500 BC) extends with the cultures of Iberomaurus ( North Africa - 20,000 to 8000 BC), Azilia ( Southern Europe - 12,300 to 9600 BC) and Swideria ( Eastern Europe - 13,000 to 9500 BC) into the preboreal. The Neolithic had already begun in the Levant , represented by the Pre-Ceramic Neolithic A (9500 to 8800 BC) and the early Pre-Ceramic Neolithic B (8800 to 7000 BC). Around 9000 BC In the Middle East, Jericho was settled for the first time, probably the oldest permanent settlement in the world. Settlements in the preboreal region were also discovered in northern Central Europe, for example near Friesack in Brandenburg . Detected net fragments point here to the importance of fishing .

In North America from 9000 BC The early Paleo- Indian Clovis culture (9000 to 8800 BC). It followed from 8900 BC. The middle to late Paleo-Indian Folsom culture based on bison hunting (8900 to 8200 BC).

See also

Individual evidence

  1. ^ Structure of the Holocene. Geozentrum Hannover (PDF file, 405 kB)
  2. ↑ Waldo Helio Door Zagwijn: Nederland in het Holoceen . In: Rijks Geologische Dienst Haarlem (Ed.): Geologie van Nederland. Deel 1, 46 pp., Staatsuitgeverij . 's-Gravenhage 1986.
  3. ↑ T. Litt et al .: Correlation and synchronization of Lateglacial continental sequences in northern central Europe based on annually laminated lacustrine sediments . In: Quaternary Science Reviews . tape 20 , 2001, p. 1233-1249 .
  4. ^ WZ Hoek: Atlas to Palaeogeography of Lateglacial Vegetations; Maps of Lateglacial and Early Holocene landscape and vegetation in The Netherlands, with an extensive review of available palynological data . In: Netherlands Geographical studies . tape 231 , 1997.
  5. ^ SO Rasmussen et al .: A new Greenland ice core chronology for the last glacial termination . In: Journal of Geophysical Research . 111, D06102, 2006.
  6. ↑ Almut Bick: The Stone Age . Theiss WissenKompakt, Stuttgart 2006, ISBN 3-8062-1996-6
  7. ↑ Johanna AA Bos and a .: Preboreal climate oscillations in Europe: Wiggle-match dating and synthesis of Dutch high-resolution multi-proxy records . In: Quaternary Science Reviews . tape 26 , 2007, p. 1927-1950 .
  8. ↑ T. Kobashi et al .: 4 ± 1.5 ° C abrupt warming 11,270 yr ago identified from trapped air in Greenland ice . In: Earth and Planetary Science Letters . tape 268 , 2008, p. 397-407 .
  9. ^ F. Wagner et al .: Century-scale shifts in Early Holocene atmospheric CO2 concentration . In: Science . tape 284 , 1999, pp. 1971-1973 .
  10. ^ SJ Johnsen et al .: The 18O record along the Greenland Ice Core Project deep ice core and the problem of possible Eemian climate instability . In: Journal of Geophysical Research . tape 102 , 1997, pp. 26397-26410 .
  11. ^ Hansjörg Küster : History of the forest , C. H. Beck, Munich 2003, ISBN 3-406-50279-2
  12. ^ S. Björck: A review of the history of the Baltic Sea, 13.0-8.0 ka BP . In: Quaternary International . tape 27 , 1995, p. 19-40 .
  13. ↑ Anja Broszinski: The subfossil diatom flora of the western Baltic Sea. Dissertation from the Johann Wolfgang Goethe University . Frankfurt am Main 2002.
  14. ↑ P. Crombé, Y. & J. Perdaen Sergeant: Le gisement mésolithique ancien de Verrebroek: Campagne 1997 . In: Notae Praehistoricae . tape 17/1997 , 1997, pp. 85-92 ( biblio.naturalsciences.be [PDF]).