Dating springlines from hydrogeological and archaeological evidence

Abstract

The relationship between prehistoric populations and water is often poorly understood, partly as a function of historical reliance on qualitative and fragmentary datasets in many regions. Here, we adopt a quantitative approach to analyze a specific aspect of the relationship between prehistoric populations and water for the Cotswold Hills, southwest UK; an area of documented hydrogeological change and extensive Neolithic (ca. 5.5 ka) activity. Using a database of all known Neolithic monuments, we interrogate the significance of water to their habitation. By marshaling a large dataset of recent (ca. 100 years) changes in the discharge and elevation of 259 springs, we establish a striking negative relationship between present-day spring discharge and annual elevation change. We then formulate an inverse problem to predict spring elevations in Neolithic times. Spring elevations are predicted to be closer to, and higher than, Neolithic-dated sites relative to the location of modern springs. These results emphasize a utilitarian and/or reverential link between water and prehistoric populations. Our approach of reconciling markedly different datasets and timescales can easily be adapted to other regions. While groundwater had behaved reasonably predictably since Neolithic times, recent human activity is (and will continue to be) far more significant in influencing groundwater behavior.