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September 19, 1991: The Iceman Natural History

The views expressed are those of the author and are not necessarily those of Scientific American.


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It was nearly noon when I arrived at the top of the ascent. For some time I sat upon the rock that overlooks the sea of ice. A mist covered both that and the surrounding mountains. Presently a breeze dissipated the cloud, and I descended upon the glacier…[]…My heart, which was before sorrowful, now swelled with something like joy; I exclaimed — “Wandering spirits, if indeed ye wander, and do not rest in your narrow beds, allow me this faint happiness, or take me, as your companion, away from the joys of life.”
Mary W. Shelley “Frankenstein“, Chapter 10 (1813)

It was a quick and lonesome death, wounded by an arrow in the back the 45 years old man bleed to death within minutes. The body was left on the site of the murder – maybe the aggressors assumed that scavengers and time would erase all the evidences- but in the cold and dry climate in 3.200m a.s.l. the body begun to desiccate and large scavengers didn’t venture in this desolate realm, only some flies were able to deposits their eggs on the body but they weren’t able to destroy it.
During the next winter snow accumulated in the gully where the body laid and in the next decades and centuries the snow transformed slowly into ice, protecting and preserving the mortal remains.

Fig.1. and Fig.2. A small snowfield on the middle of this photography is covering again the gully in which the body of “Ötzi” was found, to celebrate the discovery a memorial remembers the event.

Time passed – first decades, then centuries and even millennia. September 19, 1991 – 20 years ago – two German tourists, Helmut and Erika Simon, accidentally discovered the body emerging from the ice near the Similaun Hut (Ötztaler Tyrolean Alps) after a period of marked ablation, helped by sunny weather and the deposition of Saharan dust on the glacier ice, that absorbed much of the solar radiation.
The prehistoric mummified corpse – soon known worldwide as “Ötzi” the Iceman – together with its unique set of artefacts provided a unique opportunity for the research of a Copper-Age culture in the European Alps.

But the body and the artefacts provided also insights on the glaciers during the little known warm phases of the Holocene in Europe. This phase is practically undocumented by glacial sediments, eroded by later glacial advances, and is only recognizable by proxy data like changes in pollen diagrams or the radiometric ages of organic material.
During the last glacial maximum some 18.000 years ago the entire area of the Ötztaler Alps was almost completely ice-covered, only narrow and steep arêtes and horns protruded from the sea of ice. In the area of the Similaun Hut sharp trim lines in a height varying from 3.060m to 3.400m divide the uppermost frost-shattered crests from the lower slopes, smoothed by glacial erosion. The trim line can also recognized locally as marked weathering line that separates different oxidized reddish surfaces (the bed rock consists of Fe-rich gneiss and schist).
A second trim line is marked by an abrupt change in lichen diameter (from 100mm above to 40mm below) and density. The dating by lichenometry attributes this glaciers to the Little Ice Age (LIA, ca. in the years 1.600-1.850), which generally corresponds to the maximum Holocene glacier expansion.
The mummy itself was dated by radiocarbon dating to 4.500+-30 and 4.580+-30yr Before Present, which corresponds to a calibrated age of 5.300-5.050yr B.P. The relatively sudden burial of the corpse in a more or less permanent snow and ice cover indicates a significant climatic change that induced glacier expansion at the beginning of the Neoglaciation in the second half of the Holocene.
This inferred change of the glaciers is supported also by some soil horizons found in depression between 3.000 and 3.215m a.s.l. and dated to 5.615+-55yr B.P. (6.450-6.300 cal. yr B.P.) and 3.885+-60yr B.P. (4.416-4.158 cal. yr B.P.). Similar recent soils needed at least 5 to 12 centuries for its development, suggesting that the climatic conditions on the site were for a long time relative favourable for biological and chemical activity until a relatively quick drop of temperatures.

The Iceman and his site so reveal that between 9.000 and 5.000yr B.P. the mountain glaciers were smaller than in the second half of the Holocene. About 6.400 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. Between 5.300 to 5.050 cal. yr B.P. ago a rapid climatic change took place, producing a persistent snow cover and the expansion of glaciers which conserved the body until again the glaciers begun to retreat.
And the recent retreat of the glaciers still continues, in 1970 the glacier that revealed the mummy was part of the much greater Niederjoch-Glacier, a composite alpine glacier that descends northward in the Nieder-Valley, but only in the last 5 years this glacier lost 60-100m in length.

Fig.3. The “Similaun” as highest peak (3.597m) with his two main glaciers, the “Similaun” in foreground, and the “Niederjoch” in background. Until ca. 1970 the glaciers merged, but the glacial retreat in the last years was notable.

Fig.4. Location (black circle) of the site of the bronze-age mummy in the Ötztaler Alps. Blue areas represents the glaciers in 2003, the red line the glaciers during the Little Ice Age (ca. 1600-1850), blue, green and yellow the main glacier-stages during the Pleistocene-Holocene transition.

The artefacts of the Iceman provided also insights in the landscape in which Ötzi lived. It was an environment characterised by a rich biodiversity, he could use and in fact used an astonishing variety of plants found in his living space.
Both the axe shaft and the long bow were found in the vicinity of the corpse and were made of yew (Taxus baccata), a resistant and elastic wood typ. The quiver for the arrows was made of caprine skin and was stiffened with the elastic wood of the hazel tree (Corylus avellana). The 14 arrows were made of the hard wood of the wayfaring tree (Viburnum lantana). One is repaired, the front end being restored with dogwood (Cornus). The dagger handle is also made by hard wood from a piece of ash (Fraxinus excelsior). Its sheath was knotted from the bark of basswood (Tilia). He carried also two containers made of birch (Betula) bark, in one were found charcoal pieces wrapped in Norway maple (Acer platanoides) leaves.
Several wood species could be identified from the charcoal remains, probably spruce (Picea/Larix-type), pine (Pinus mugo-type), green alder (Alnus viridis), some Pomoideae which were probably Juneberry (cf. Amelanchier ovalis), dwarf willow (Salix reticulata-type) and elm (Ulmus).
A sort of backpack was constructed from a thick branch of hazel (Corylus avellana) bent into a U-shape, together with two coarsely-worked laths of larch (Larix decidua).

The majority of wood species found with the Iceman grow in the montane regions (valley bottoms to 1.800m), although some subalpine (1.800-2.500m) and alpine (above 2.500m) conifer species are also represented. Their ecological requirements point to the transition zone between thermophilic 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.

So the botanical evidence seems to confirm a climate comparable to pre-industrial conditions and implies a glacial extent similar, if not slightly minor, to the recent past. This has very important influence on the reconstruction of past and modern climatic and glacial development and can contribute to the actual discussion about climatic change.

Fig.5. Simplified Holocene subdivision and glacier variations in the European Alps according to MAISCH (2000),  PATZELT et al. (1996) and PATZELT (2000).The first half of the Holocene is characterized by a general lowstand of the glaciers. The Iceman died during a phase of glacier advance (Rotmoos II), afterwards the glaciers display minor variations approaching the year 1850 highstand.

References:

BARONI, C. & OROMBELLI, G. (1996): Short paper – the alpine “Iceman” and Holocene Climatic Change. Quaternary Research 46: 78-83
MAGNY, M. & HAAS, J.N. (2004): Rapid Communication – A major widespread climatic change around 5300 cal. yr BP at the time of the Alpine Iceman. Journal of Quaternary Science 19(5): 423-430
MAISCH, M. (2000): The longterm signal of climate change in the Swiss Alps: Glacier retreat since the end of the little Ice Age and future ice decay scenarios. Geogr. Fis. Dinam. Quat. 23: 139-151
OEGGL, K. (2009): The significance of the Tyrolean Iceman for the archaeobotany of Central Europe. Veget. Hist. Archaeobot. 18:1-11
PATZELT, G.; BORTENSCHLAGER, S. & POSCHER, G. (1996): Exkursion A1 – Tirol: Ötztal-Inntal. Exkursionsführer DEUQUA-Tagung Gmunden/Oberösterreich 14-16.9.1996: 23
PATZELT, G. (2000): Natürliche und anthropogene Umweltveränderungen im Holozän der Alpen. Rundgespräche der Komission für Ökologie, Bd. 18 Entwicklung der Umwelt seit der letzten Eiszeit: 119-125

David Bressan About the Author: Freelance geologist dealing with quaternary outcrops interested in the history and the development of geological concepts through time. Follow on Twitter @David_Bressan.

The views expressed are those of the author and are not necessarily those of Scientific American.





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