Magnetostratigraphy of Pleistocene Sediments from the Republic of Georgia - Dating and Correlation of Climate Signals

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The discovery of hominin remains of as many as six individuals, approx. 1.8 Ma in age, in Dmanisi, Southern Georgia, marks the first appearance of human occupation in Eurasia, significantly earlier than previously thought and thus changed our understanding of the causes of the first wave of emigration out of Africa substantially. Recent studies have shown, that the only African elements in the Dmanisi site are the remains of Homo Georgicus itself and associated tools. Unambiguous European affinities of the Dmanisi fauna do not support the idea, that the early hominins followed the migration patterns of large herbivores to ensure their food supply. The details of the Dmanisi hominins furthermore suggest, that local or global changes in climate are the key driving factor for early humans to venture towards Europe, because other hypothesis are disproved. In the early Pleistocene, rapid changes of warm/cold periods are documented based on global oxygen isotope records. It has been proposed, that during one of the warm periods the onset of desertification in eastern Africa forced early hominins to migrate into Europe. It is debated, however, whether the human remains in Georgia demonstrate favorable climatic conditions for early hominins and prove a long term occupation of this area, or the Caucasus represents a stepping stone along a migration path into Eurasia. For investigation of local climatic conditions, high resolution palynology is an ideal technique to map the paleoenvironmental conditions and local responses to global climate. For such studies, however, very precise age control isinevitable.High resolution magnetostratigraphy has been shown to be a very precise correlation and dating tool especially concerning young sediments. Thus, magnetostratigraphy provides the basis for successful studies of short term variations of the paleoenvironment.In Western Georgia there are a number of sedimentary sections with proposed deposition ages from ~3 million years up to the present. This time span includes the hominid bearing deposits at Dmanisi as well as lake sediments from Armenia studied earlier (Ba1210/14-1). What makes the Georgian shallow marine sections special, however, is the extremely large amounts of pollen which can give a high resolution picture of the paleoenvironmental conditions during times of human migration through the Caucasus. Correlating the magnetostratigraphic data from Georgia with those from Armenia will allow us to compare the climatic situation in Western Georgia and Armenia during the Pleistocene.It is therefore planned to study two large sections in Guria which cover a sufficiently long time span to include the 1.8 Ma time mark (age of the Dmanisi hominins) and the southern Armenian sections. The results of this study will contribute to a precise reconstruction of the paleoclimate and paleoenvironment of the Caucasus during a crucial phase of hominin occupation in the area.