Case Study 6: Mesolithic and Neolithic Lithic Scatters at Stainton West, Carlisle, Cumbria
Antony Dickson (Oxford Archaeology North) and Paul Clark (RPS Consultancy)
Introduction
This case study describes the excavation methodology, post-excavation assessment and analytical studies applied during the analysis of a large chipped stone and coarse stone tool assemblage recovered during excavations at Stainton West, Carlisle, Cumbria (Brown et al. in prep).
The date, size and good preservation of the lithic assemblage, as well as the extended sequence of activity it represents, make it one of the most important early prehistoric sites investigated within the North West, and indeed nationally. Due to this significance, along with the potential of the lithic resource to inform on many of the aims and objectives included in the Regional Research Framework agenda, a programme of analytical studies was designed and agreed on by Oxford Archaeology North (OAN), the developer and local planning authorities.
Background
The trial trench evaluation of Stainton West identified a palaeochannel and alluvial deposits along with eight lithics. Based on this, the site was originally identified by the project brief as an area for strip, map and record excavation.
This phase of works was duly undertaken by OAN in 2009 and revealed little beyond the deposits identified during evaluation. However, following heavy rainfall, a significant number of lithics weathered out of the stripped surface. This material was mapped and recovered, and a series of test pits were hand-excavated to assess the density of the lithic distribution across the site. These produced a substantial number of lithics, exhibiting a similar technological character to the material recovered from the surface.
Upon excavation, it was found that the site comprised features and an extensive lithic assemblage, associated with a complex sequence of deposits within a palaeochannel, spanning the Late Mesolithic period to the Bronze Age.
It is apparent that the site could have been missed at the early stages of characterisation and demonstrates the difficulties of identifying archaeological sites within floodplain environments.
Even if it had been ploughed, fieldwalking would not have readily identified the significance of the site, due to the fact that the lithic assemblage and associated structures were buried under alluvial and colluvial deposits. This demonstrates the need to implement appropriate evaluation methodologies, which take into account a broad range of issues including landscape setting and geomorphological context, in order to manage lithic sites effectively at the pre-determination and/or post-determination stages of the planning process.
Excavation methodologies
The site was excavated using a grid-square system (Fig 6.1), utilising whole-earth sampling, except for cut features which had their finds recorded in three dimensions. The site area, excluding the palaeochannel, was subdivided into 886 1m x 1m grid squares. These were excavated stratigraphically by context in spits and all the spoil was retained and stored.
The palaeochannel was excavated by hand in bays and the lower levels produced Mesolithic organic remains and palaeoenvironmental sequences which could be reconciled with occupation in the grid-square area.
All the retained spoil from the grid squares was processed on site through a system of mechanical sieves which were provided and set up, specifically for the project, by ADC ArcheoProjecten, an archaeological unit based in Amersfoort in the Netherlands (Fig 6.2). This system proved extremely reliable in rapidly processing large volumes of sediment to very gently recover archaeological finds.
Approximately 270,000 litres of spoil were sieved, producing a large number of residues, which were logged, dried and labelled.
Post-excavation methodologies
All the lithic material contained in the context residues was subject to assessment. This involved sorting the lithics into their relevant typological category relating to core technology, debitage and retouched items, and by raw material type, which included various cherts and flint, chalcedony/agate, tuff, pitchstone, quartz, and raw materials that were not readily identifiable.
During the assessment, it became clear that some of the context assemblages contained collections of lithics that showed enough similarities in colour, texture, lustre, inclusions and cortex type to indicate that they had been struck from the same nodule. These, along with a few short re-fitting sequences, were recorded as knapping groups.
Once each context assemblage had been sorted, the subsequent data were then entered into an online relational database. Each lithic-type entry represented a row of data forming a single record relevant to a specific context and group. This amounted to a record of over 303,000 lithics, including approximately 5,900 microliths, 236 coarse stone tools, 21 complete and fragmented axe/adzes and 610 pieces of ochre.
The database was developed by Oxford Archaeology to collate and manage information and integrate the project archive, while also having further functionality such as remote access, facilities for multiple users and advanced querying. The latter proved invaluable, especially in regards to generating sub-samples of lithics for a variety of integrated studies, including a detailed lithic typological and technological attribute analysis, use-wear analysis, spatial analysis and a variety of raw material sourcing studies (Table 6.1).
Table 6.1 The methods, results, rationale and interpretative value of the analytical techniques used during the analysis of the Stainton West worked stone assemblage (© 2018 Oxford Archaeology North; all rights reserved)
Technological analysis
Sample size: about 19,000
Methods: Typological and technological attribute analysis of chipped stone cores, debitage and tools. Technological analysis of coarse stone tools. Technological analysis of ochre.
Results: Identified chipped stone reduction strategies across different types of raw material. Identified different types of coarse stone tools and interpreted their use. Identified the use of ochre and its spatial relationship with the chipped stone and coarse stone tools.
Number of staff: 2
Rationale: Integral to Updated Research Aim 5 in the Stainton West post-excavation assessment report. The worked stone assemblage, due to its size, composition and chrono-technological character, is considered to be of regional, national and, certainly of north-west European, if not, international importance. Technological analysis of a sample of the assemblage undertaken to explore the technological character of the worked stone assemblage; to identify chrono-technological developments; and social organisation across the site area. Analysis undertaken to complement the study of the site stratigraphy, chronology and palaeoenvironment.
Interpretative value: The results aided the interpretation of patterns of occupation across the site; the technological character of this distribution; and the landscape value of the site within a regional context.
Raw material analysis
Sample size: about 400
Methods: A variety of geochemical analyses were used: Inductively Coupled Plasma Mass Spectroscopy (ICP-MS); Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); X-Ray Fluorescence (XRF); Petrological Thin Section (PTS)
Results: Identified that raw materials were derived from a variety of sources local to and beyond the region. Confirmed the integrity of the knapping groups. Aided in the interpretation of social organisation across the site area.
Number of staff: Staff and students from Bradford university; Reading University; the University of Central Lancashire; the Implement Petrology Group and two independent researchers.
Rationale: Integral to Updated Research Aim 5 in the Stainton West post-excavation assessment report. The wide variety of materials at Stainton West met the need for the development of a programme of scientific analysis for characterising the sources of Mesolithic flint and chert implements, which has been established as an important research priority in the Regional Research Framework. Confirm the integrity of the knapping groups identified during assessment and understand the spatial distribution of raw materials and their significance to social organisation across the site.
Interpretative value: The geochemical study of lithic raw materials at the site was used to answer questions about the nature of population mobility and range of influence of the communities that visited the site. It also allowed a greater understanding of the social organisation of stone working activities and the chronological development of procurement strategies.
Microwear analysis
Sample size: 744
Methods: Microscopic analysis of ware patterns on stone tools and debitage undertaken within a laboratory using specialist equipment and recording procedures.
Results: Identified tool and debitage use across the site area potentially indicating task organisation. Also the study of wear pattern preservation informed on site formation processes.
Number of staff: Staff from Bradford University's Lithic Microwear Research Laboratory
Rationale: Integral to Updated Research Aim 5 in the Stainton West post-excavation assessment report. Microwear analysis can identify how individual tools were used; the character of activities undertaken at the site; the use of particular resources; settlement organisation; seasonality; and site formation. Therefore, it can contribute greatly to a regional and national understanding of Mesolithic practices.
Interpretative value: Highly effective in adding a human dimension to the study of worked stone from the site. Highlighted the potential for the spatial organisation of specific tasks across the site area. Also identified the multi-functional role of some microlith types.
Residue analysis
Sample size: 44
Methods: Chemical analysis of residues adhering to stone tools and debitage in order to identify the composition of the material. Attempted dating of organic residues.
Results: Identified birch bark tar on a leaf-shaped arrowhead. Unfortunately the analysis of potential residues on the microliths and debitage revealed contamination by plasticisers.
Number of staff: Staff from Bradford University's Hunter Gatherer Laboratory
Rationale: The potential to date organic residues offered an alternative method to refine the site chronological model. Unfortunately this did not take place due to sample size and contamination.
Interpretative value: In the context of Stainton West this analysis added extra interpretative value to social organisation at the site.
Spatial analysis
Sample size: All worked stone from the site area
Methods: The use of a Graphic Information System (GIS) to compile shapefiles showing dot density distributions of all types of chipped stone, coarse stone tools and ochre. The creation of interpolation plots to define spatial relationships between specific lithic types. Plotting the results against the site area and associated features in order to identify the spatial organisation of stone working at the site.
Results: Identified stone working areas across the site area relating to the reduction of specific raw materials. Identified meaningful distributions of specific tool types relating to the social organisation of the site. Identified the integrity of the worked stone assemblage in relation to the stratigraphic sequence. Identified the presence of structures as semi-circular settings of worked stone, which had not been identified during excavation.
Number of staff: 1
Rationale: Integral to Updated Research Aim 5 in the Stainton West post-excavation assessment report. Due to the collection strategy employed during excavation which practised 100% recovery the spatial preservation was found to be excellent and allowed detailed spatial analysis to be undertaken.
Interpretative value: Spatial analysis was highly effective in picking apart what would ostensibly have been seen as a palimpsest. It was the main technique used to draw together the results of the other analytical techniques. Highly effective in defining social organisation and the spatial distribution of activities and tasks across the site area.
Results
The results of the use-wear study were exceptionally good (Table 6.1), with a higher than average success rate in terms of the number of pieces within the sample preserving evidence for microwear, allowing a greater understanding of the range of tasks undertaken at the site.
One of the main observations from the analysis is that microliths were used in a variety of tasks and not just as armatures for hunting weapons. The spatial analysis of the results (Table 6.1) has shown that some tasks, such as hide-working and butchery, were consistently undertaken in the same areas of the encampment over several phases of occupation (Fig 6.3).
The study also helped understanding of the formation processes behind the creation of some stratigraphic units, thus benefiting the interpretation of the site.
The results of the raw material sourcing studies have provided added detail with regard to the connections which the people who visited Stainton West had with the wider landscape (Table 6.1). Chert from southern Scotland and the northern Pennines arrived at the site, along with pitchstone from the western coast of Scotland and flint from the north-east of England (Fig 6.4).
The procurement of these materials was part of the wide-ranging mobility patterns practised by those visiting the site, elements of which were also probably connected to the negotiations and obligations bound up in extensive social networks.
By examining the chronological and spatial distribution of the raw materials tested during the studies it can be suggested that these networks were in place by the middle of the 5th millennium cal BC and probably continued until at least the Early Neolithic. Thus, the use of raw material studies has highlighted the importance of the site and its place within a wider social landscape.
The chert sourcing also confirmed the coherence of over 100 knapping groups identified during the lithic assessment, concomitantly affirming the spatial integrity of the lithic assemblage and the success of the methodologies employed during excavation.
Conclusions
In summary, the excavation and post-excavation methodologies employed at Stainton West were invaluable for the interpretation of the site. The grid-square system was demonstrated to be of sufficient resolution to allow the successful identification of spatial patterns across the site, including the identification of structures, and the distribution of knapping groups (Table 6.1).
Additionally, the sieving set-up proved an excellent system for the high-quality recovery not only of lithic artefacts, but also of organic remains. It has been shown to be an incredibly useful tool for the archaeologist, and should certainly be considered for much wider use on archaeological projects, across a range of periods and geographic regions. Moreover, the methodologies employed during the analysis of the lithic assemblage, such as spatial and use-wear analyses, allowed greater understanding of the way of life of the people who made and used the stone tools, something that is not usually considered in sufficient depth in the conventional technological analysis of Late Mesolithic struck lithic assemblages.
References
Brown, F, Clark, P, Dickson, A J, Gregory, R and Zant, J, in prep From an Ancient Eden to a New Frontier: an archaeological journey along the Carlisle Northern Development Route. Lancaster: Oxford Archaeology
