| Preceded by thePleistocene |
| Holocene Epoch |
|---|
 Canopy of deciduous temperate forest, which spread to the north in the Atlantic Period. |
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Blytt–Sernander stages/ages
*Relative to year 2000 (b2k). †Relative to year 1950 (BP/Before "Present"). |
TheAtlantic in palaeoclimatology was the warmest and moistestBlytt–Sernander period,pollen zone and chronozone ofHolocenenorthern Europe. The climate was generally warmer than today[citation needed]. It was preceded by theBoreal, with a climate similar to today's, and was followed by theSubboreal, a transition to the modern. Because it was the warmest period of the Holocene, the Atlantic is often referenced more directly as theHolocene climatic optimum, or just climatic optimum.
The Atlantic is equivalent topollen zone VII. Sometimes a Pre-atlantic or early Atlantic is distinguished, on the basis of an early dividing cold snap. Other scientists place the Atlantic entirely after the cold snap, assigning the latter to the Boreal. The period is still in the process of definition.[1]
It is a question of definition and the criteria:Beginning with the temperatures, as derivable fromGreenlandice core data, it is possible to define an 'Early' or 'Pre-Atlantic' period at around 8040 BC, where the18Oisotope line remains above 33 ppm in the combined curve after Rasmussen et al. (2006),[2] which then would end at the well-known6.2 ka BC (8.2 ka calBP)-cold-event.
Or one single Atlantic period is defined, starting at that just mentioned cold-event.
After a lake-level criterion, Kul’kova and others[3] define the Atlantic as running from 8000 to 5000 (cal?) BP. Early Atlantic, or AT1, was a time of high lake levels, 8000–7000 BP; in Middle Atlantic, AT2, lakes were at a lower level, 7000–6500 BP; and in Late Atlantic I, 6500–6000 BP, and II, 6000–5700 BP, levels were on the rise. Each period has its distinctive ratios of species.
According to the ice-core criterion it is extremely difficult to find a clear boundary, because the measurements still differ too much and alignments are still under construction. Many find a decline of temperature significant enough after 4800 BC.Another criterion comes from bio-stratigraphy: theelm-decline. However, this appears in different regions between 4300 and 3100 BC.
The Atlantic was a time of rising temperature and marine transgression on the islands ofDenmark and elsewhere. The sea rose to 3 m above its present level by the end of the period. Theoysters found there required lower salinity.Tides of up to 1 m were present. Inland, lake levels in all north Europe were generally higher, with fluctuations.
The temperature rise had the effect of extending southern climates northward in a relatively short period. Thermophilous ("heat-loving") species migrated northward. They did not replace the species that were there, but shifted the percentages in their favor. Across middle Europe, theboreal forests were replaced by climax or "old growth"deciduous ones, which, though providing a denser canopy, were more open at the base.
The dense canopy theory, however, has been questioned byF. Vera.[4]Oak andhazel require more light than is allowed by the dense canopy. Vera hypothesizes that the lowlands were more open and that the low frequency of grass pollen was caused by the browsing of large herbivores, such asaurochs andwild horses, a thesis referred to as thewood-pasture hypothesis.
During the Atlantic period thedeciduous temperate zone forests of south and central Europe extended northward to replace the boreal mixed forest, which found refugia on the mountain slopes.Mistletoe,Water Chestnut (Trapa natans) and Ivy (Hedera helix) were present inDenmark. Grass pollen decreased. Softwood forests were replaced by hardwood.Birch andpine were replaced byoak,linden (lime, both small and large leaf species),beech,oak,hazel,elm,alder, andash, spreading to the north from further south. The period is sometimes called "the alder-elm-lime period".[5]
In northeast Europe, the Early Atlantic forest was but slightly affected by the rise in temperature. The forest had beenpine with an underbrush of hazel, alder, birch, andwillow. Only about 7% of the forest became broad-leaved deciduous, dropping to Boreal levels in the cooling of the Middle Atlantic. In the warmer Late Atlantic, the broad-leaved trees became 34% of the forest.
Along the line of theDanube and theRhine, extending northward in tributary drainage systems, a new factor entered the forest country: theLinear Pottery culture, clearing the arable land byslash and burn methods. It flourished about 5500–4500 BC, falling entirely within the Atlantic. By the end of the Atlantic, agricultural and pasture lands extended over much of Europe and the once virgin forests were contained withinrefugia. The end of the Atlantic is signaled by the "Elm decline", a sharp drop inElm pollen, thought to be the result of climate, disease orhuman food-producing activities.[5] In the subsequent cooler Sub-Boreal, forested country gave way to open range once more.
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The best picture of Atlantic Period fauna comes from the kitchen middens of theErtebølle culture ofDenmark and others like it. Denmark was more of anarchipelago. Humans lived on the shorelines, exploiting waters rich in marine life, marshes teeming with birds, and forests wheredeer andboars as well as numerous small species were plentiful.
The higher water levels offset the effects of thesubmarine toxic zone in theBaltic Sea. It contained fish now rare there, such as theanchovy,Engraulis encrasicolus, and the three-spinedstickleback,Gasterosteus aculeatus. Also available werepike,whitefish,cod, andling. Three kinds ofseals were found there, the ringed, harp and grey. Mesolithic man hunted them andwhales in the estuaries.
The main birds were maritime: thered-throated diver, theblack-throated diver, and thegannet. TheDalmatian pelican (Pelecanus crispus), which is now found only as far north as south-eastern Europe, has been found in Denmark. Thecapercaillie, as is the case now, was found in forested areas.
In the lofty canopy could be found a continuous zone of smaller animals, such as the ubiquitoussquirrel (Sciuris vulgaris). Daubenton's bat (Myotis daubentonii) was common. In and around the big trees hunted thewildcat,pine marten,polecat (Mustela putorius), andwolf.
The forest floor was prolific with larger browsers and rooters such as thered deer,roe deer, andwild boar. Not all the former plains mammals had abandoned the country. They remained in the open forest and meadows. These include theaurochs, ancestor of cattle, and the wildhorse which, as a discovery, was something of a revelation. The horses were not entirely hunted out, were not confined to the plains further east, and were not entirely the property of theIndo-European cultures there. The Mesolithic Ertebølle people were hunting them in Denmark.[6]
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Human cultures of Northern Europe were primarilyMesolithic. TheKongemose culture (6400–5400 BC) settled on the coastline and lake margins of Denmark. Late in the Atlantic, Kongemose culture settlements were abandoned because of the rising water of theLittorina Sea; and the succeedingErtebølle culture (5400–3900 BC) settled more densely on the new shorelines.
Northeastern Europe was uninhabited in the Early Atlantic. When the Mesolithic Sertuan Culture appeared there in the Middle Atlantic, around 7000 BP, it already had pottery and was more sedentary than earlier hunter-gatherers, depending on the great abundance of wildlife. Pottery was being used around the lowerDon andVolga from about 8000 BP.
In the Late Atlantic, Sertuan culture evolved into Rudnya culture, which used pottery like that of theNarva andDnieper-Donets cultures. That use of pottery upsets the idea that pottery belongs to the Neolithic. Further to the south, theLinear Pottery culture had already spread into the riverlands of Central Europe and was working a great transformation of the land. On the steppe to the east, theSamara culture was deeply involved with large numbers of horses, but it is not yet clear in what capacity.
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