Atlantic (period)

As Atlantikum or medium heat time is one time only blurred v. between about 8000 BC and 4000 BC in Northern Europe referred to comprehensive air stage, which corresponds to the pollen zones VI and VII. These warmest and most humid period of the Blytt - Sernander sequence is also called the " Holocene Optimum". The chronology differs according to scientific field, processing status and spatial scope in some cases substantially (see adjacent graphic synopsis ). The symbol key in geology for the period is as follows: qhat. In U.S. English the Atlantic period is also called the " Holocene Thermal Maximum ( HTM) ".

3.1 Temperature development
3.2 sea 3.2.1 Baltic Sea Region
3.2.2 North Sea

4.1 temperatures

7.1 Inserting the Neolithic
7.2 megalithic

Definition

The term Atlantikum was introduced in 1876 by Axel Blytt for the first time in the scientific literature. He distinguished the Atlantic period with Atlantic, so oceanic climate from the much cooler, preceding Boreal.

Stratigraphy and dating

The Atlantic period following the previous Boreal and, in turn, replaced by the following Subboreal.

The Atlantic period, in a mature Atlantic period, which corresponds to the pollen zone VI, and in Junior Atlantikum (pollen zone VII) are divided, with the boundary line at 6000 years comes to lie BC.

The boundaries of the Atlantic to the other stages are relatively blurred. Its onset is usually set at 7270 years BC. The actual Atlantikum is often also preceded by a so-called Präatlantikum or Early Atlantic period, the lower limit at 8040 BC and the upper limit at 6200 BC are (calibrated calendar years). According to Rasmussen et the Präatlantikum characterized by a relatively high O18 isotope content above 33 ppm (the values are taken from ice cores in Greenland ). For the beginning of the Atlantic also the striking cold relapse offers at 6200 BC. Kul'kova and others define the Atlantic period than the period 8000-5000 BP and divide it based on sea water levels in three stages ( from young to old):

Late Atlantic period AT3 - 6500-5700 Jahre BP - again rising water levels - again slight increase in temperature
Mid- Atlantic period AT2 - 7000-6500 Jahre BP - relatively low water level - gradual temperature decrease
Early Atlantikum AT1 - 8000 bis 7000 years BP - High water level - optimum temperature

In the Late Atlantic period she also divorced two sub- steps:

Late Atlantic period I - 6500-6000 Jahre BP
Late Atlantikum II - 6000-5700 Jahre BP

Also for the end of the Atlantic, it is difficult to find a clear solid ceiling. It is usually given 3710 BC, some authors also see the after 4800 BC taking place temperature decrease to be significant. The biostratigraphy uses the elm decline, however, the diachronic was 4300-3100 BC.

Temporal classification

Note: Only the fields marked with a black dividing line boundaries are more or less exactly; they are based on annual layers in lake sediments in north-central Europe and are, strictly speaking, only for air levels. The other boundaries are determined unsafe and not rigid. In particular, the boundary between Central and Jungholozän is highly variable. In the stages of culture the different regional development is observed.

Global Aspects

In paleoclimatology, the term refers to a Blytt - Sernander - air stage of the Holocene. Here is the discussion on the level and sequence of Holocene temperature fluctuations continues unabated. As the gray shows ( purely statistical! ) Averaging the graphic to sharp boundaries do not indicate exactly. The climax of the Atlantic because of the humid climate and increased monsoon rains, the Sahara was a rich animal and plant life as they seem to be rather dry at the present warming period.

Temperature development

Global perspective is important to note that the warm periods were regionally pronounced differently and were not observed at the same time. There is evidence locally in some cases significantly higher temperatures than in the last decades of the 20th century prevailed. However, the spatial and temporal resolution of the existing climate proxies are not allowed to draw the conclusion that it was globally warmer over several decades in the Atlantic than in the second half of the 20th century. The concept of " Holocene temperature optimum " is only relevant regional and global context is not applicable.

Sea level

The higher temperatures led to the sharp decline of the glaciers. The melting especially the North American glaciers led to a rapid rise in sea level. This in turn probably about 6,700 BC, the overflow of the Mediterranean in the earlier ( 120 meters) deeper Black Sea ( see discussion there) result. In the Alps the glaciers around 7,000 BC melted back very strong, with a striking re- advance from about 4,700 BC The rapid rise in sea level of the Boreal continued in the older Atlantikum continued. At the beginning of the Atlantic, the sea level was still about 30 feet below the present level. The rate of increase was about 15 mm / year for the Older Atlantic period. Years ago, about 7000 BP, the increase then began to weaken dramatically and so was at the end of the Atlantic, the sea level at 2 meters below sea level. The low rate of increase in the younger Atlantic period was only 0.3 mm / year.

Baltic Sea Region

In the area of today's Baltic Sea was taken shortly before the start of the Atlantic to 7500 BC, the Ancylus Lake, which had emerged by isostatic land uplift from the sea Yoldia. The level of Ancylussees was considerably below the former sea levels in the North Sea ( - 30 meters above sea level). Between 6500 and 6000 BC, the land bridge between Denmark and Sweden was broken, it made the Littorinameer. This marine incursion resulted in the Baltic region a fairly rapid rise in sea level by 15 meters.

North Sea area

The before beginning of the Atlantic to 9000 BC onset Flanders transgression caused the sea level to rise rapidly in the North Sea. He reached around 6600 BC - 45 meters below sea level and around 5100 BC already - 15 meters below sea level. Then it came towards the end of the Atlantic to a sea level fall or standstill in the North Sea area.

Northwest European aspects

Generally, a combination of the Holocene thermal optimum with palaeobotanical subdivisions, which are defined generally by Firbas (1949 ), problematic. B. Frenzel (1993 ) denies even that the climate of the Holocene vegetation of the 'll read, because the man has already intervened in this timely and sustainable manner:

The beginning of the Atlantic, just the beginning of pollen zone VI by Firbas is, in this sense defined by the re- immigration of oaks and alders in the hitherto prevailing pine ( birch ) forest. This happened north of the Alps from the 8th - 7th millennium BC Since the re- immigration of the various tree species from south to north was, arise in this relationship, different chronologies between south and north, as well as favorable and unfavorable locations.

The Atlantic period ends after Firbas with the end of his second section, the pollen zone VII, defined by two elm decline in the 4th millennium BC Since not only the decline today mainly to anthropogenic influence (reinforced pollarding leads to Splintkäfer and fungal attack, see sexton 2003:83 has to be recycled ), and this classification has no relation to a defined end of a " climatic optimum ".

Temperatures

Presumably, the climate was not only regionally warmer ( in Northern Europe up to 2.5 ° C) than today, but also more humid. The average temperatures during the Atlantic period elderly were similar to today's values. Located at 7600 years BP optimum had up to 0.5 ° C higher average values than today. Then the temperatures dropped during the Middle and Later Atlantic period under several oscillations slowly back to the now prevailing value.

Due to a now at least for the northern hemisphere generally accepted sharp cold relapse btw 6300-6100 BC ( in the Alps Misox fluctuation; . Eng " 8.2 ka cold -event " ) expect some time before that, the preceding morning heat time ( Boreal ), others use an "early " Atlantic period, and correlate this with the Firbas pollen zone VI. In general, recent work, for example, at the LMU Munich, the Geo - Research Institute Hannover, as well as the Institute of Silviculture in Göttingen the Atlantic period but put - to about 6,000 BC - after this incision.

Vegetation history development

During the Atlantic period, the deciduous forests of the temperate zone of South and Central Europe extended to the north and displaced the boreal mixed forest, but in the Bergslagen still persisted. Thus, for example, were in Denmark mistletoe, water chestnut (Trapa natans ) and ivy (Hedera helix) present. The grass pollen, however, were generally declining. Soft woods such as birch and pine were advancing from southern climes of hardwoods such as oak, linden (Tilia cordata and Tilia platyphyllos), beech, hazel, elm replaced (Ulmus glabra), alder and ash. This vegetation history section is referred to as alder - elm -Linden - time.

In north-eastern Europe, the forest in the early Atlantic period was affected only slightly by the general rise in temperature. The forest was here mainly of pine, the undergrowth was composed of hazel, alder, birch and willow together. Only about 7% of the pollen stock fell here on broad-leaved deciduous trees, during the cooling phase of the Middle Atlantic period then went back to the level of even the Boreal back. With the temperature increase of the Late Atlantic period, the proportion of broad-leaved deciduous trees increased then at least to 34%.

From 5500-4500 BC, then came along the Danube and the Rhine and its northern tributaries, the Linear Pottery Culture in the woods before and put them with slash and burn. Towards the end of the Atlantic cropland and grazing land had already extended over much of Europe and forced the original forests now more and more in refuges back. There also occurred the so-called Dutch elm case, a sudden decline in elm pollen, which may be due to human cultivation of cereals and vegetables. In the adjoining, cooler Subboreal the forest was replaced again by open meadows.

Fauna

The best picture of the fauna of the Atlantic can be the basis of catering waste Ertebølle culture Denmark win. Denmark was formed at that time an archipelago whose human inhabitants who settled mainly along the coast. At sea they had rich fishing grounds and the marshes were visited by flocks of seabirds. The forests were roamed by very numerous big game such as cervids, and swine -like, but also on small game was not lacking.

Due to the higher water levels the effects of the toxic zone were attenuated in the Baltic Sea. This relatively rare taxa anchovy Engraulis encrasicolus such as and the three -spined stickleback Gasterosteus aculeatus able to spread now. Present were also pike, whitefish, halibut and ling. In the estuaries of three species of seal and whales were hunted by the people of the Mesolithic.

As expected, seabirds such as red-throated diver, black-throated divers and gannets were in the majority. Even the Dalmatian Pelican (Pelecanus crispus ), whose northern border is today in South Eastern Europe, was then used in Denmark. The capercaillie kept as even today in forest areas.

The tree crown area was populated by small mammals such as squirrels Sciurus vulgaris the omnipresent. The Daubenton's bat was very common. In the forests, the wild cat, pine marten, polecat European hunted (Mustela putorius ) and Wolf.

On the ground, large mammals such as deer roamed, red deer and wild boar. Former residents of the open grassland, such as the bison and wild horses were also still present, contrary to expectations. The wild horses were at that time not yet extinct by hunting and also not only limited to the steppes of Eastern Europe; they were hunted both by the people of Ertebølle culture in Denmark as well as in the Hungarian steppe.

Cultural development

The Atlantic period essentially covers the Spätmesolithikum as well as the early, the middle and the Neolithic. As the carrier cultures acted in Northern Europe ( Baltic States, Denmark, England, Northern Germany and Sweden) Maglemosian culture ( 9000-6500 BC ) for the Spätmesolithikum, as well as the Kongemose culture ( 6000-5200 BC) and the Ertebølle culture ( 5100-4100 BC) to the Early Neolithic. In the British Isles is from 6000 BC, the Neolithic Larnian ( Northern Ireland) and from 4000 BC to lead the Obanian (western Scotland). In the western North Rhine -Westphalia is Spätmesolithikum Hülstener the group to meet.

At the end of the Mesolithic in Europe were the first farming cultures, such as from 5800-5500 BC, the La - Hoguette group in the south and from 5500-4900 BC, the Alfold - linear ceramic and the Körös culture in the southeastern Central Europe. In the actual central Europe there was at this time the Linear Pottery Culture. In the northern central Europe and southern Scandinavia in the Funnel Beaker culture developed around 4300 BC.

Onset of the Neolithic

In the Near East ( with Anatolia) was until 6800/6500 BC already encountered the Preceramic Neolithic B, which was replaced between 6500-5500 BC by the Ceramic Neolithic ( in the eastern Mediterranean from 6200 BC). In Central Europe, the transition to the Neolithic period from 5500 BC was carried out with the band ceramics, but in the Baltic region until much later ( around 4300 BC ) to the Funnel Beaker culture.

Megalithic

The in Europe and the Mediterranean in parallel associated with the megalithic Neolithization can be traced back to around 4700 BC with the investments in Normandy and the necropolis of Bougon. It ended (not at the same time everywhere) with the outgoing Subboreal. Carrier culture of megalithic sites was the Funnel Beaker culture in Europe.