Erdalen event

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The Erdalen event was a Holocene cold relapse around 7400 BC. AD. It was characterized by glacier advances in Norway and low lake levels in southern Sweden made in China , it corresponded to a cold phase.

definition

The Jostedalsbreen

The Erdalen event, known in English as the Erdalen event , was named after the U-shaped glacier valley Erdalen (or Erdal ). The north-west running valley starts from Erdalsbreen , a glacier tongue of Jostedalsbreen . The terminal moraine assigned to the event is still more than 1 kilometer below the terminal moraine from the Little Ice Age .

In addition to the type locality , moraines of a comparable position were also found in many other glacier valleys in Norway.

Dating

The age of the cold relapse occurring at the border from the preboreal to the boreal varies, depending on the author, between around 8,300 and 7,000 BC. BC (mostly narrowed to 8300 to 7700 BC). A more precise dating could be made by Eikeland (1991) on lake sediments. The investigation found radiocarbon ages ranged from 9460 to 9060 BP . This corresponds to the period from 8854 to 8245 BC. Chr. Nesje and Kvamme (1991) found 9100 ± 200 radiocarbon years corresponding to the period 8295 to 7910 years BC. BC or recalibrated with CalPal 8571 to 7996 BC Chr.

description

The Erdalen event is equivalent to Bond event 6 . The latter is characterized by a cold maximum around 7800 BC. And glacier advances around 7600 BC Followed by a drought peak around 7500 BC. The Jostedalsbreen, for example, was between 8100 and 7600 BC. Chr. Expanding significantly. The northern Folgefonna , Grovabreen , Hardangerjökul , central Jotunheimen and Snøhetta reacted very similarly . In Germany the Erdalen event correlated with the Holzmaar described boreal fluctuation (engl. Boreal Oscillation ).

The Erdalen event was a very significant cold relapse, recognizable by the lowering of the firn line by up to 325 meters. The cold relapse was accompanied by a reduction in precipitation of up to 71%, as calculations by Dahl and Nesje (1992) show. At the same time, summer temperatures fell by 3.0 + 0.2 / -0.3 ° C.

causes

The main cause of the Erdalen event is considered to be the enormous freshwater influx into the North Atlantic and the Arctic Ocean ; The rapid increase in temperature at the beginning of the Holocene had led to a significant melting of the ice sheets and pack ice , which was reflected in a sudden rise in sea level.

See also

Individual evidence

  1. ↑ Svein Olaf Dahl et al .: Timing, equilibrium-line altitudes and climatic implications of two early-Holocene glacier readvances during the Erdalen Event at Jostedalsbreen, western Norway . In: The Holocene . tape 12, 1 , 2002, pp. 17-25 .
  2. ↑ gallops Feldt, Gunnar: Reconstruction and regional correlation of Holocene lake-level fluctuations in Lake Bysjön, South Sweden . In: Boreas . tape 17.2 , 1988, pp. 165-182 .
  3. ↑ Zhou Jing, Wang Sumin, Yang Guishan, Xiao Haifeng: Younger Dryas Event and Cold Events in Early-Mid Holocene: Record from the sediment of Erhai Lake . In: Advances in Climate Change Research . 3, Suppl. 2007, p. 1673-1719 .
  4. ↑ Nesje, A., Kvamme, M., Rye, N. and Lovlie, R .: Holocene glacial and climate history of the Jostedalsbreen region, western Norway; Evidence from lake sediments and terrestrial deposits . In: Quat. Sci. Rev. Band 10 , 1991, pp. 87-114 .
  5. ↑ Shakesby, RA, McCarroll, D. and Caseldine, CJ: New evidence for Preboreal deglaciation of south-central Norway . In: Norsk Geografisk Tidsskrift . tape 44 , 1990, pp. 121-130 .
  6. ^ McCarroll, D .: Schmidt hammer relative-age evaluation of a possible pre-'Little Ice Age' Neoglacial moraine at Leirbreen, southern Norway . In: Norsk Geologisk Tidsskrift . tape 69 , 1989, pp. 125-130 .
  7. ^ Eikeland, R .: Yngre Dryas - Preboreal Lokalglasiasjon and stratigrafi på Sunnmøre and i Nordfjord . In: PhD Thesis, University of Bergen . 1991.
  8. ↑ Nesje, A. and Kvamme, M .: Holocene glacier and climate variations in western Norway: evidence for early Holocene glacier demise and multiple neoglacial events . In: Geology . tape 19 , 1991, p. 610-612 .
  9. ^ Wanner, Heinz et al.: Structure and origin of Holocene cold events . In: Quaternary Science Reviews . tape 30 , 2011, p. 3109-3123 .
  10. ↑ Nesje, A. et al .: Holocene glacier fluctuations of Flatebreen and winter-precipitation changes in the Jostedalsbreen region, western Norway, based on glaciolacustrine sediment records . In: The Holocene . tape 11,3 , 2001, pp. 267-280 .
  11. ↑ a b Nesje, A .: Latest Pleistocene and Holocene alpine glacier fluctuations in Scandinavia . In: Quaternary Science Reviews . tape 28, 21-22 , 2009, pp. 2119-2136 .
  12. ↑ Brathauer, U., Brauer, A., Negendank, JFW and Zolitschka, B .: Rapid climate changes at the beginning of today's warm period . In: Biennial Report GeoForschungsZentrum Potsdam 1998/1999 . 2000, p. 29-33 .
  13. ^ Porter, SC: Equilibrium-line altitudes of late Quaternary glaciers in the Southern Alps, New Zealand . In: Quaternary Research . tape 5 , 1975, p. 27-47 .
  14. ↑ Dahl, SO and Nesje, A .: Paleoclimatic implications based on equilibrium-line altitude depressions of reconstructed Younger Dryas and Holocene cirque glaciers in inner Nordfjord, western Norway . In: Palaeogeography. Paleoelimatology. Palaeoeeology . tape 94 , 1992, pp. 87-07 .