Intra‐interstadial environmental changes in Last Glacial loess revealed by molluscan assemblages from the Upper Palaeolithic site of Amiens‐Renancourt 1 (Somme, France)

Abstract

The Amiens-Renancourt 1 site recently yielded one of the most important Upper Palaeolithic human occupations of northern France by the number of flint artefacts and especially by the presence of Venus figurines. All the material comes from a single archaeological layer located in a tundra gley bracketed by loess units. A multi-proxy study combining a detailed stratigraphy, luminescence and radiocarbon datings and high-resolution (5 cm per sample) grain size and molluscan analyses was therefore carried out to reconstruct and date the associated environmental changes and to determine the exact context of the human occupation. The chronological frame thus established supports the correlations of the archaeology-bearing tundra gley and of an underlying arctic brown soil with Greenland interstadials GI-4 and GI-3. Composition changes in the molluscan population enabled the identification of transitional and optimum phases and sub-phases within these two pedogenetic horizons. A conceptual correlation model linking molluscan phases with millennial-scale variations of Greenland ice-core and Sieben Hengste speleothem climate records is proposed. The Human occupation appears contemporaneous to the end of the stadial-interstadial transition of GI-3. Synchronous in Amiens-Renancourt 1 and Nussloch, subsequent micro-gleys may also result from a regional/global forcing. Such a level of detail is unprecedented in a loess sequence.

Last Glacial Maximum active layer thickness in Western Europe, and the issue of ‘tundra gleys’ in loess sequences

“…Similar horizons were later found in many European LPS (e.g. Vandenberghe et al, 1998;Vandenberghe and Nugteren, 2001;Antoine et al, 2009;Kadereit et al, 2013;Terhorst et al, 2015;Fischer et al, 2020;Schmidt et al, 2021;Moine et al, 2021) and referred to as 'tundra gleys' by comparison with modern High-Arctic soils (e.g. Tedrow, 1966Tedrow, , 1968; to our knowledge this term was first used by Haesaert and Van Vliet-Lanoë, 1981), 'Gelic Gleysols' according to the FAO (1974) soil classification or 'Cryosol' according to World Reference Base for Soil Resources (IUSS Working Group WRB, 2015).…”

“…The presence of earthworms producing calcite granules, which are currently absent in permafrost areas, and the molluscan assemblages are consistent with temperature improvement during the formation of these horizons, which is contradictory to the permafrost hypothesis. Radiocarbon ages on charcoals, molluscan shells and earthworm granules closely match those of interstadials (Vandenberghe and Nugteren, 2001; Moine et al , 2017, 2021; Fischer et al , 2020). Earthworms, which feed on organic material, suggest that vegetation developed at that time. In more continental Eastern Europe (Ukraine; e.g.…”

“…Radiocarbon ages on charcoals, molluscan shells and earthworm granules closely match those of interstadials (Vandenberghe and Nugteren, 2001;Moine et al, 2017Moine et al, , 2021Fischer et al, 2020). Earthworms, which feed on organic material, suggest that vegetation developed at that time.…”

“…Recently, detailed analysis of the assemblages of molluscan shells associated with 'tundra gleys' has provided evidence for temperature improvement during their formation (Moine et al, 2008(Moine et al, , 2021. Radiocarbon dating of shells and calcitic earthworm granules also convincingly places their development within interstadials (Vandenberghe and Nugteren, 2001;Moine et al, 2017Moine et al, , 2021Fischer et al, 2020). However, the assumption that they correspond to waterlogged active layers has not been reconsidered.…”

Were Hominins Specifically Adapted to North-Western European Territories Between 700 and 600 ka? New Insight Into the Acheulean Site of Moulin Quignon (France, Somme Valley)

“…However, it is highly likely that human occupations from this period only correspond to short incursions of human groups during the summer season. Taking into account the wide dating error bars, it is also possible that the Moulin Quignon human occupation took place during a short interstadial period (≤1-2 ka) characterised by a milder climate (especially during summer season), as is the case for example for Upper Palaeolithic hunters during the Last glacial period in the area (Renancourt: Paris et al, 2016;Moine et al, 2021), or for the Acheulean occupation at Cagny-la-Garenne during the Early MIS 12 glacial period (Tuffreau and Lamotte, 2010;Lamotte and Tuffreau, 2016).…”