- Allerød Oscillation
The Allerød period is a part of a temperature oscillation toward the end of the last
glaciation, during which temperatures in the northern Atlanticregion rose from glacial to almost present day level. The Allerød is a warm, moist Blytt-Sernanderperiod named after a type site in Allerød municipalityin Sjælland, Denmark(near Copenhagen), where deposits created during the period were first identified and published in 1901 by Hartz and Milthers. The Allerød corresponds to Pollen zone2.
The oscillation occurred in the Bølling and Allerød periods, with a brief intermission in some regions known as the
Older Dryasperiod. Temperatures returned to glacial levels in the succeeding Younger Dryasperiod. Subsequently the climate warmed and the present interglacial period started.
The start of the Allerød depends on whether an
Older Dryasis present and how much time is to be allotted to the latter. A conventional date of 14,000 BP is typical. Roberts (1998) uses 13,000 BP for the end of the period.
The Greenland Oxygen isotope record shows the warming identified with the Allerød to be after about 14,100 BP and before about 12,900 BP. C-14 dates from an excavation on the shore of
Lake Neuchatel, Switzerland, furnish a date of 14,000 BP, calibrated, for the start of the Allerød. Pollen cores from Berezina plain, Belarus, give 11,800-10,900 BP uncal. Various researchers have similar ranges: 12,000-11,000, 11,700-11,000, etc. They all seem to roughly concur.
The Allerød occurred during the last interstadial of the
Pleistocene: the Windermereof Britain, the Woodgrangeof Irelandand the Two Creeks Intervalof North America. Although interstadials are defined by region, the Allerød period is not, being global in its effects; that is, the temperature and sea level rose everywhere, not just in north Europe.
During the Allerød, which foreshadowed the modern climate, mixed evergreen and deciduous forests prevailed in Eurasia, more deciduous toward the south, just as today.
Birch, Aspen, spruce, pine, larchand juniperwere to be found extensively, mixed with Quercusand Corylus. Poaceaewas to be found in more open regions.
Some animals hunted were the
red deer, moose, horse, Irish elkand beaver. The ubiquitous brown bearwas present as well.
Man in north Eurasia was still in the
reindeer huntingstage. A variety of Palaeolithiccultures prevailed in Europe: the Federmesser, Lyngby, Bromme, Ahrensburg and Swiderian. To the south and far east the Neolithichad already begun.
* [http://www.ac.by/publications/litho/litho16.html Belarus]
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