Late Neolithic to Middle Bronze Age (around 4900-3100 cal. BP) lake-level fluctuations at Lake Neuchatel (Switzerland) as reflected by the sediment sequence of the site of Colombier/Les Plantees de Rive: Palaeoclimatic and archaeological implications

摘要

Recent archaeological investigations at the site of Colombier/Les Plantees de Rive (COL-PR) on the northwestern shore of Lake Neuchatel (Switzerland) revealed an exceptional concentration of anthropic structures from the Late Neolithic to the Late Bronze Age interbedded within an alternation of terrestrial and lacustrine deposits. The chronology is based on radiocarbon dates from terrestrial material and on artefacts found in archaeological structures. Using various proxies, the sedimentological analysis of the COL-PR sediment sequence allows the reconstruction of lake-level fluctuations for the period 4900-3300 cal. BP. Three major lake-level highstands occurring at ca. 4900 (Late Neolithic), 3650 (Early Bronze Age) and 3400 cal. BP (Middle Bronze Age) have been related to the possible influences of decreases in the solar activity sometimes accentuated by increases in volcanic activity. The COL-PR site provides robust data to document the climatic deterioration assumed to be responsible for the abandonment of the lake-dwellings north of the Alps during the Middle and the early Late Bronze Age. In addition, the interbedding of successive monuments within terrestrial as well as lacustrine deposits suggests a significant role played over hundred years by the collective memory in the perpetuation of the ceremonial and funeral vocation of the site and its spatial organisation at the interface between lacustrine and terrestrial domains, despite interruptions provoked by major lake-level rises associated with worsening of climatic conditions.