The Campanian Ignimbrite Factor: Towards a Reappraisal of the Middle to Upper Palaeolithic “Transition” .
Résumé
In this chapter, we present results of a detailed investigation of the Campanian Ignimbrite (CI) eruption that took place c 40,000 BP. We endeavour to show that the potential impacts of this underrated eruption, in cambination with other environmental factors, demand e reconsideration of the processes and rythms that took place in western Eurasia at a crucial point in time represented by the so-called Middle to Upper Palaeolithic 'transition'. The source of the CI eruption was in the Phlegraean Fields Caldera, north-west of Naples in southern Italy (Figure 2.1). Petrologically identified CI ash layers have been reported from inland and marine sequences throughout south-eastern Europe from the Tyrrhenian Sea to the Volga River in Russia. The extensive CI deposits can be recognised as the product of the largest volcanic eruption during the past 200,000 years in the Greater Mediterranean area, defined here as including the Balkans, Anatolia, and the Pontic (Black Sea) regions. The eruption was large in both intensity and magnitude. The CI sulphate signal has been recognised in the GISP2 ice core, Greenland (Fedele et al 2003). This eruption can be dated to c 40,000 BP by means of argon-argon measurements supported by correlations with the Greenland ice record. This temporal placement draws attention to the climatic context of a time period centred on 40,000 BP, midway through the Weichselian (Last Glacial) Interpleniglacial, which corresponds to stage of Late Pleistocene environmental straitgraphy (MIS 3 ; Figures 2.2 and 3). The volcanic catastrophe precisely overlapped with the culmination of the penultimate Bond cycle of Stage 3, a cooling trend that began ~45,000 BP. We therefore propose that a positivefeedback triggered by an exceptional concurrence of factors - climatic change, glaciation, ocean-ice exchange, and latitude - is likely to have had hemispheric or wider effects. The most pronounced of these was the abrupt cooling coeval with the Heinrich Event 4 (HE4) about 40,000 BP. The scenario of a 'volcanic winter' should therefore be considered. The archaeological changes immediately following the CI are a sign of conspicuous interference with human populations. The coincidenceof a volcanic eruption and Palaeolithic phases had been noted previously (eg, Mussi 2001), but has not been effectively addressed in spite of abundant archaeological evidence in southern Italy and elsewhere. Furthermore, we surmise that the hiatus in human occupation must have has a causal relationship not only with the impact from the blast but with the ecological disruption it generated. It could be argued that only when humans are examined as ecosystem components can the effects of the CI on social and cultural processes - including the Middle to Upper Palaeolithic 'transition' - be understood.