The sudden burial of the corpse in a permanent snow cover occurred 5300–5050 cal yr B.P., indicating a significant climatic change that induced glacier expansion at the beginning of Neoglaciation.
The snowfield on the right of this picture represents the depression in which the corpse was found.
During the last glacial maximum (LGM, ca. 18.000 yr), the entire area was completely ice-covered, only narrow and steep arêtes and horns protruded from the ice. In the area of the Similaun Hut sharp trimlines in a height varying from 3060m NW of the Similaun Hut to 3400m on Finail-Spitze divides the uppermost frost-shattered crests from the lower slopes, smoothed by glacial erosion. The trimline can also recognized locally as marked weathering line that separates different oxidized surfaces (the bed rock consists of Fe-rich gneiss and schist).
A second trimline is marked by an abrupt change in lichen diameter (from 100mm above to 40mm below) and density. The dating by lichenometry attributes this glacier stand to the Little Ice Age (LIA), which generally corresponds to the maximum Holocene glacier elevation.
Some soil horizons were found in depression between 3000 and 3215m a.s.l. and dated to 5615+-55 yr B.P. (6450-6300 cal yr B.P.) and 3885+-60 yr B.P. (4416-4158 cal yr B.P.). Similar recent soils needed at least 5 to 12 centuries for development, suggesting that the climatic conditions on the site were for a long time relative favourable and constant.
The Iceman and his site reveal that between 9000 and 5000 yr B.P. the mountain glaciers were smaller than in the second half of the Holocene. About 6400 cal. yr B.P. and for several centuries after, an ice-free peripheral belt allowed the accumulation of organic matter and developments of relatively thick soils. The Iceman was killed on the site during summer, and covered by snow soon after. Until 5300 to 5050 cal yr B.P. ago, a rapid climatic change took place, producing a persistent snow cover and a glacier expansion, which conserved the body until his discovery in modern times.
Detailed information about the lifestyle and environment of the Iceman is based on both on-site and off-site data. The on-site data are represented by his clothing, the wooden artefacts, plant macro remains recovered during two archaeological excavations at the discovery site in 1991 and 1992, as well as the micro and macro fossil content of the food residue from the mummies intestines. They provide information about Neolithic edible and otherwise useful plants, the making and suitability of his equipment, prehistoric diet, the season of his death, his social status, palaeo-environment and the taphonomy of the find assemblage. Off-site data are represented by palynological and macroremains analyses of peat deposits from mires in the nearer and wider vicinity of the discovery site, which reveal the vegetation and climate history as well as human impact on the vegetation during the time of the Iceman.
Both the axe shaft and the long bow were found in the vicinity of the corpse and were made of yew (Taxus baccata). The quiver was made of caprine skin and was stiffened with hazel wood (Corylus avellana). The 14 arrows were made of the wood of the wayfaring tree (Viburnum lantana). One is repaired, the front end being restored with dogwood (Cornus). The dagger handle is made from a piece of ash (Fraxinus excelsior). Its sheath was knotted from the bark of linden (Tilia).
He also had with him two containers made of birch (Betula) bark, in one were found charcoal pieces wrapped in Norway maple (Acer platanoides) leaves.
All in all, the majority of wood species found with the Iceman thrive in the montane regions (valley bottoms to 1,800 m),although some subalpine (1,800-2,500 m) and alpine (above 2,500 m) species are also represented. Their ecological requirements point to the transition zone between thermophilous mixed-oak forest communities (Quercetalia pubescenti-petreae) and the montane spruce forest (Piceetum montanum). Norwegian maple (A. platanoides), European yew (T. baccata), ash (Fraxinus sp.), lime (Tilia sp.) and elm (Ulmus sp.) allow to infer a humid habitat with a mineral rich, free-draining soil and a mild winter climate. All that is similar to the present-day conditions in the woodlands found on the slopes and in gorges in the lower Schnalstal and Vinschgau in South Tyrol, where it is assumed he lived.
The Schnals-valley and his entrance in a narrow gorge - the steep walls are very exposed and sunny, so that very dry-tolerant plant species can be found here, like cactus species (Opuntia ficus-indica), yew and shrubs communities and steppe-like grass patches. On more humid slopes a larch or spruce forest develops.
So the botanical evidence seems to confirm a climate comparable to modern conditions, and implies a glacial extent similar, if not slightly minor to the present.
This has very important influence on the reconstruction of past, and modern climatic and glacial development, and at last the actual discussion about climatic change.
BARONI, C. & OROMBELLI, G. (1996): Short paper – the alpine “Iceman” and Holocene Climatic Change. Quaternary Research 46: 78-83
Keine Kommentare:
Kommentar veröffentlichen