Gm Cruise

Lago di Bargone, Liguria, N Italy: a reconstruction of Holocene environmental and land-use history

Sediment micromorphology, chemistry and magnetic susceptibility of basin edge deposits at the small, mid-altitude peat site of Lago di Bargone, eastern Liguria, Italy, is compared with a full Holocene palynological sequence and radiocarbon dates from the central part of the peat bog. Micromorphology and MS550 results show that Neolithic to Copper Age forest disturbances and clearings as inferred from the pollen diagrams, occurred during a period of lower water-tables and intermittent drying out of the basin edge deposits. Extensive deforestation and expansion of heath and grassland during the Iron Age and Roman periods is associated with increases in soil erosion and in micromorphological indications of burning. It is argued that the very fine size range of the charred fragments seen in thin sections and the seeming absence of charcoal of coarser size range suggest a system of light, controlled burning, possibly akin to the local tradition of using fire to control weeds and to encourage new grass and herbaceous growth, and not local forest clearance by fire. Micromorphology of the late-Holocene peat contains herbivore dung possibly indicating the use of the site as a watering hole by domesticated stock. The overlying colluvium displays evidence of deep-seated erosion of the local soils and geology which is most likely to have been associated with local mining activities.

Short‐term, post‐burial change in a humic rendzina soil, Overton Down Experimental Earthwork, Wiltshire, England

The 1992 excavation of the Overton Down Experimental Earthwork provided a unique opportunity to study pedogenic change in a humic rendzina soil 32 years after burial beneath a chalk bank containing a central stack of turves. Investigations focused on soil structure, porosity, organic matter, plant remains, pH, carbonate, iron, and magnetic susceptibility. Standard methods of chemical analysis and micromorphological description were complemented by quantitative analysis of soil thin sections. The results demonstrate both the speed of change (e.g., compaction and organic decomposition have reduced the thickness of the Ah horizon by >50% in places), and the way the microenvironment of burial can significantly affect the nature and direction of change (e.g., differences in pH, carbonate, soil structure, and earthworm activity between soils buried beneath the chalk rubble and the central turf stack). These have important implications for the preservation of biological and cultural remains, and for the maintenance of their stratigraphic integrity.