Vol 5 - Issue 1

Archaeology, Society and Environment

List of Articles

Particles translocation exists in both subarctic/alpine and sub-arid climate contexts. The geochemical surface properties of the particles (loess, alluvium, fossil beaches or slope deposits) induce a translocation of fine or silty clays under control of the pH. The process of illuviation corresponds to an early and precise period of soil evolution, depending on decarbonization or desaturation. It requires the percolation of a water flash: a meltwater, or a harsh rain in arid context. Any excess cations (Ca++ or Mg++ in alkaline or Al2 O3 in acid context), allows rapid flocculation and locks the leaching process. Several processes can hinder fine illuviation as in acid, calcareous or volcanic palaeoenvironments. The “Zero Point Charge” (ZPC) of the mineral surface or of clay-humic complex regulates the optimum conditions for particle dispersion or flocculation. This implies that illuvial process is an early stage in the soil evolution within a narrow pH window, but it can be reactivated by the chemical rejuvenation of the soil after erosion or by loess deposition as natural or anthropogenic superficial inputs, by burial, by changes in hydrologic functioning or in vegetation cover. The soils of our regions are the result of a complex and cumulative history since at least 50 ka or even 120 ka, modulated by the evolution of the climate and the biosphere. Clay coatings do not necessarily represent Holocene or older interglacials but can attest as well to Weichselian interstadials, even very brief. A rejuvenation or fertilization by a sedimentary contribution or a truncation will allow a very brief return of the illuvial functioning followed by a rapid return to an oligotrophic status of the surface soil. This phenomenon also makes it possible to understand the succession of illuvial phases observed in thin sections. Most Bt horizons are cumulative and often polyphased. This succession of events, in addition to the evolution of the climate and the precipitation regime, makes it possible to understand, the genesis of the current pedocomplex in function of the loessic quaternary inputs. In regions with limited sedimentary input, the soil very early acidifies, degraded and the illuvial horizon no longer evolves since at least the MIS 3, or the Last Interglacial, as in the south-west of France and the margins of the Massif central or the Vosges. An acido-complexolysis of the clays is superimposed on the leaching, especially in the glosses of the inherited fragipan.

In order to gain a more detailed understanding of the interrelations between archaeology and pedology, it is possible to describe in detail the targeted objects and the protocols used by each, by comparing concrete experiments and attempting to make the comparison more general. We have decided to include here a few considerations on the metaphysics of time, because we feel that they are rarely used in the ordinary scientific exercise, and yet are likely to shed new light on the subject. Thus, the fundamental ontological distinction between events and processes seems to us to be particularly fruitful in this debate and allows us to temper somewhat any attempt at fusion (or intersection) between these disciplines.

Excavations carried out on a 5-hectare hillslope, in the commune of Woippy (near Metz, France), uncov-ered estate active between the 7th and 12th centuries. Finds include areas of dwellings and associated plots of land and paths. The steep hillside was developed on a low-permeability silty-clay to sandy-clay substrate. The soil horizons un-covered are linked to the small strip-shaped affected by erosion to various extents relating to topography. In addition, the excavations uncovered a complex system of drains and water-collecting ditches, which constituted a preliminary stage to the siting of the buildings and gradually organized the final shape of the plot. The water drainage management thus appears to be a key factor in the archaeological structuring of the landscape, just as to recreating drains and retention basins became necessary during the 2018 excavation to limit the impact of colluvium in the present-day village.