Samstag, 22. August 2009

Mountains as only witnesses

Like islands in the sea small hills, only some dozen meters in height, rises from the flat landscape of the "Orla-valley" south of Weimar. These “mountains” consists of limestone of ancient reefs, growing once in the Permian "Zechstein - sea". Tectonic and erosion have done they dirty work since them, leaving behind only isolated “Zeugenberge” (rude translated in Witnesses mountains) from the marine deposits.

The archeological site "Gamsenberg".

In a flat landscape every vantage point, that enables a hunter to overlook a vast territory, is of strategic importance. And in fact during the last ice age early man observed from this Zeugenberge the glacial steppe in search for the big herds of mammals.

Today the summits of these hills are mostly flat, covered by dense shrubby vegetation, and the surrounding landscape is characterized by villages, fields and scattered trees.
During excavations in a depression on the summit of the “Gamsenberg” – presumably in a karst depression or a collapsed cave - underlying 1,5m thick Loess deposits from the last glacial, a fossil soil was discovered, that contained lithic artefacts, bone fragments and charcoal. This paleosoil developed under warm climatic conditions on rubble of the underlying limestone, this rubble also shows cryoturbation.

The stratigraphic section of the archeological site "Gamsenberg". The upper part consists of Loess deposits, that overlay periglacial displaced rubble and rock fragments (cryoturbation).

Dating of glacial loess samples resulted in ages between 44.700+-4.500 and 41.900+-4.600 years. Between this stratigraphic layer and the horizon with the artefacts bones of micro mammals were found, especially the remains of pika (Ochotona) and lemming (Lemmini) indicate dry, cold conditions. Dating of the layer with the artefacts gave an age of 52.500 to 70.900 years, the bone fragments in this layer belong to animals like elk (Alces), horse (Equus hydruntinus and taubachensis), stag (Cervus elaphus), deer (Capreolus capreolus), auerochs (Bos) or bison (Bison) and a undetermined proboscidean (Mammuthus ?).
This animal assemblage is indicative for a dry, continental to boreal climate, with a mosaic of tree spots and steppe areas. The paleobotanic remains are also indicative to a climate with warm summers, but an annual average temperature to low to permit the establishment of deciduous tree forests.

The only time period that coincide with the radiometric ages, and also with a change between warm to cold climate temperatures, like indicated by the sedimentological and paleontological evidences, is the Odderade interstadial between 70 to 60kyrs during the Weichsel ice age.

Humans, presumably Neanderthals, used the Zeugenberge as ideal vantage point to overlook the steppe with sparse wood spots during an interstadial of the last glacial period. Here they prepared their tools, using rocks like flintstone (found in morainic deposits 20 kilometres away), quartz, greywacke and siliceous schist. After spotting a herd of animals, and (hopefully) successful hunt, they returned and butchered their prey on this site. Then, during full glacial conditions some 50.000 years ago wind transported dust covered the abandoned site, and only today, the karst fissures return their hidden secrets.

References:

WEBER, T. (1996): Das Paläolithikum und das Mesolithikum in Mitteldeutschland. Archäologie in sachsen-Anhalt Nr.6. Archäologische Gesellschaft in Sachsen-Anhalt, Halle

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