Piles in the picture. A study of the physical disturbance and archaeological information loss caused by piling through archaeological sites and features, based on photographs.

This thesis addresses the disturbance of different types of foundation piles in different types of soil, and the loss of archaeological information associated with that disturbance. The research was conducted to provide a theoretical and practical framework for assessing building disturbances, specifically when using archaeology-sustainable building plans. Based on 10.000 photographs of piles on excavations collected throughout the Netherlands, the disturbance around 1499 individual piles was measured, significantly increasing the number of available field samples. The results show that the disturbance of piles is largest in constructions and smallest in peat, while the disturbance of piles in clay, sand and made ground is found to be comparable. Furthermore, the disturbance around displacement piles is found to be larger than around replacement piles. However, the diameter of replacement piles is larger by default, causing the total disturbance of displacement piles to be smaller overall. Based on the disturbances measured around the different piles, an analysis was then made of the loss of archaeological information caused by this disturbance. To this end, interviews were held with 21 archaeological experts, who assessed the information loss based on photographs of piles through specific archaeological contexts. Based on their expert judgement, it is clear that information loss is not determined by the size of the disturbance, but rather by the nature of the archaeological context and the placement of the piles. Information loss is limited in large archaeologic complexes, solid or linear structures and when conducting artefact-based research (as long as displacement piles are used). Contrary, information loss can occur when piling through burials, small archaeological complexes or sites with organic structures of artefacts. However, this loss of information is not always noticeable because it occurs mainly when very specific questions are asked, requiring specialistic research methods and accurate sampling and study. This type of research is, unfortunately, not standard on every excavation. Furthermore, information loss also occurs prior to, during and after archaeological excavations, caused by the limited time and funds available in today’s developer-driven archaeological world. As a result, preservation in situ through archaeology-sustainable building can often be considered to be preferable to a development-driven excavation. The thesis ends with a proposed new archaeological policy on archaeology-sustainable building. Rather than a policy based on archaeological value alone, this new policy should explicitly consider the negative effects (or lack thereof) of building activities on the archaeological remains. Only when the information loss caused by building activities is potentially larger than the information loss caused by a development-driven excavation, should such an excavation be considered. In all other circumstances, archaeology-sustainable building provides a valid alternative.