Saturday, 15 July 2006
117-1

Geochemical Signatures From Within and Around Old Farms.

Donald A. Davidson, Univ of Stirling, Stirling, FK9 4LA, United Kingdom, Clare Wilson, Univ of Stirling, Stirling, FK9 4LA, United Kingdom, and Malcolm Cresser, Univ of York, Environment Department, York, YO10 5DD, United Kingdom.

This project aims through sampling of well documented old farms to test the hypothesis that geochemical signatures can be associated with different areas of former human activity. Six farms from across the UK and abandoned between the late 19th Century and 1940 were sampled. Each farm had a known history of use based on living memories and documentary records, and each provided equivalent functional areas representing a range of human activities; hearth, house (kitchen), byre, midden, garden, arable fields, pasture and off-site reference soils - generally communal grazing land. Samples were taken from top-soils (0-20 cm) across a 1 m grid within each functional area and test pits allowed additional sampling from the floor layers of the buildings. The results show that of the 48 elements analysed, levels of all but Cd were enhanced in the soils of at least one farm. The pattern of enhancement was both element and site specific. For some farms there was a significant, but generalised, enhancement within and immediately around the buildings. For these farms there were no significant differences in soil element concentrations between the on-site functional areas. For other farms differential enhancement was apparent, i.e. not only were soil concentrations significantly higher than the off-site reference soils, but there were also significant differences in concentrations between the soils of the on-site functional areas.Concentrations of Ba, Ca, P, Pb, Sr, and Zn consistently seem to follow the latter pattern, whilst most additional elements, including Co, Cr, Cu, Eu, Fe, La, Mn, Y, and Rb provide this level of information at one or more farm sites, and particularly at Olligarth and Grumby. Both of these farms have an igneous geology and occupy well-drained sites. Only Ti, Cs, Na, V, Zr and some REEs failed to show significant between functional area enhancement at any of the six sites. The basic pattern of enhancement is that Ca and Sr are concentrated in hearths, P in byres and middens, and Pb in the hearths, middens and houses. Levels of enrichment relative to the unmanured outfields and off-site reference soils vary from x 3.7 for Ba in the middens, x 4.7 for P in the byres, x 12 for Zn in the houses, and x 48.6 for Ca in the hearths. Absolute concentrations also vary markedly between sites, however, there are similarities in the basic pattern of enhancement between the farms with the highest levels of P in byres and the highest levels of Ca, Sr and Pb in the hearths and houses. One suite of elements (Ba, Ca, P, Pb, Sr, and Zn) show patterns of enhancement that can consistently be linked to former activity areas to confirm the original hypothesis.

Table 1: Differentiation of functional areas based on selected element concentrations

Farm

Auchindrain

Balnreich

Cwm Eunant

Far House

Grumby

Olligarth

Ba

x

xx

xx

x

xx

xx

Ca

x

xx

xx

xx

xx

xx

Co

x

x

xx

xx

Cu

x

xx

xx

x

xx

Mn

x

xx

xx

xx

Nd

x

xx

x

xx

xx

xx

Ni

x

x

x

x

x

x

P

xx

xx

x

x

x

xx

Pb

x

xx

xx

x

xx

xx

Sr

x

xx

xx

xx

xx

xx

Y

x

x

xx

xx

Zn

xx

xx

xx

xx

xx

xx

Significant differences indicated as x general enhancement in element concentration in soils associated with buildings (houses, byres, middens and gardens) relative to the surrounding fields,

xx as above, but additionally differences in element soil concentrations between individual on-site functional areas (houses, byres, hearths, middens, gardens and fields).


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