Delivering the Benefits of Aggregates Levy Sustainability Funded Research on River Valley Archaeological Sites in the Severn-Wye Catchment, UK

Abstract

The recently published Mineral Extraction and Archaeology: A Practice Guide (English Heritage, 2008) identifies the use of geomorphological mapping and specialist remote sensing technologies allied to other techniques as important tools for use in the investigation of deeply buried archaeological sites. Such approaches are particularly valuable within environments like river valleys where prospection is particularly difficult due to the masking effect of alluvium; however, some of these techniques are unproven in several major river catchments where aggregate extraction is significant and they have yet to be widely integrated in commercial practice as part of the planning process. Methodological approaches using these techniques have largely been developed since 2002 through a number of research projects supported by the Aggregates Levy Sustainability Fund (ALSF) and English Heritage. They focus on enhancing understanding of the geoarchaeological and chronological development of river valley floors and thus the environment(s) within which archaeological sites have developed and are preserved. Light Detection and Ranging (LiDAR)-derived digital terrain modelling supported by information from other sources is used to map landform units (terraces, palaeochannels, terrace ‘islands’ and edges, etc.) within a Geographic Information System (GIS) framework.The high horizontal and vertical resolution of LiDAR allows microtopography to be mapped and this is often indicative of sub-surface geomorphological structures. In conjunction with historic environment record (HER) derived data this allows the macro- and micro-topography, relative chronology, and likely archaeological resource of key landform units to be modelled more accurately than has been previously possible. This enables areas of different archaeological potential to be highlighted, thus enabling more tightly focused, evidence-based evaluation and mitigation strategies to be developed. Other approaches such as specialist geophysical survey and, where organic material is sparse, the use of optically stimulated luminescence (OSL) dating can also be integrated to great effect to test the chronostratigraphic models produced.The use of this new ‘toolkit’ has a particularly high potential for application within large-scale, mineral extraction developments in river valleys, supporting the delivery of knowledge-based and proportionate projects at both pre- and post-determination stages as recommended in the minerals practice guide. This article focuses on a recent ALSF supported research project in the Lower Severn Valley which has tested the effectiveness of elements of the ‘toolkit’ within this major river catchment. This is accompanied by a case study of an evaluation undertaken in the Lugg Valley, a tributary of the River Wye in Herefordshire. This employed many of these techniques and provides one of the first examples of a commercially driven project where the considerable benefits of this approach to both archaeological curators and developers have been realized.