The Acheulean in the South Caucasus (Georgia): Koudaro I and Tsona lithic assemblages

The Southern Caucasus/Transcaucasia was occupied by human groups throughout the Pleistocene from 1.8 Ma (Dmanisi). A long chronological gap currently separates this earliest assemblage from the first evidence of (Acheulean-type) bifacial technology, as assemblages with bifaces do not seem to be older than 500 ka. Acheulean sites are frequent on the southern edge of the Great Caucasus but are absent on the northern side. Most of these are badly or non-dated open-air sites. There are, however, three cave sites in Georgia with archaeological sequences comprising lithic assemblages related to the Acheulean: Koudaro I, III and Tsona, located on the Great Caucasus. The altitude of these sites ranges from 1500 to 2200 m (a.s.l.) indicating occupations in a high mountainous context. Following a new technological analysis of the lithic series, this paper focuses on the assemblages from Koudaro I and Tsona and describes the strategies implemented for core and bifacial technologies in relation to palaeoenvironmental data and raw material procurement. Koudaro I indicates that both debitage and shaping took place in the cave, whereas only various heavy-duty tools were brought to Tsona, probably for short-term and specialized occupations. Acheulean groups occupied high altitudes during temperate periods and raw material procurement suggests hominin mobility between the low plateaus and the Caucasian valleys. The sites suggest that Acheulean groups extended their available territories into the Great Caucasus when climatic conditions were propitious. Moreover, comparisons between Levantine and Georgian series suggest that the southern flanks of the Great Caucasus mountain range gave rise to a local evolution of Acheulean features after the arrivals of hominin groups with the bifacial technology, likely from the Levant.