4. Project Organisation and Planning
Government guidance set out in the National Planning Policy Framework (NPPF) (Ministry of Housing, Communities and Local Government 2021) enshrines the principle of sustainable development in the planning process. Where archaeological projects are commissioned to inform the planning process the information sought should be proportionate to the significance of the heritage asset and the potential impacts of the proposed development.
Assessments of heritage assets in advance of determinations of planning applications should therefore be sufficient to provide an understanding of the significance of heritage assets and their settings affected either directly or indirectly by the development proposals (e.g. desk-based assessment or field evaluation where appropriate).
4.1 Specifications and briefs
These guidelines are applicable to all archaeological projects, but are aimed primarily at those undertaken as part of the planning process.
Providing an accurate estimate of costs for radiocarbon dating before a full assessment has been undertaken is inherently problematic. In cases where this is required, ‘ring-fenced funds for scientific dating’ in the overall budget should be identified. It is, however, much more satisfactory if projects adhere strictly to management principles, such as those outlined in MoRPHE (Historic England 2015c; Fig. 30), and post-excavations costs are identified as part of the assessment process.
For sites where radiocarbon dating can be expected to form an important part of a project (e.g. prehistoric sites, sites with waterlogged environmental remains) then specification of a fixed percentage of the overall tender for ‘ring-fenced funds for scientific dating’ would be prudent. The use of these funds would only take place following approval by the curator of costs resulting from the assessment.
If, following assessment, the requirements for radiocarbon dating are not as extensive as envisaged, then not all the ring-fenced fund would be required. A practice such as this would encourage contractors to submit realistic tenders and thus avoid the tendency for very low post-excavation costs in project budgets.
Strategies for radiocarbon dating should be included in Project Designs and Written Schemes of Investigation. Definitions of briefs, specifications and project designs can be found in the Association of County Archaeological Officers (1993) Model Briefs and Specifications for Archaeological Assessments and Field Evaluations and the Chartered Institute for Archaeologists (CIfA) Standard and Guidance series (2014a–c; 2020a–d).
Curators who need further advice on the potential for using radiocarbon dating on specific sites can obtain independent non-commercial advice from Historic England (see Appendix). Where advice is obtained from a commercial contractor, it is the responsibility of the commissioning body to ensure that vested interests are openly declared, and that subsequent competition is fair (CIfA 2014c).
Specifications and briefs should ask for radiocarbon dating and chronological modelling to be carried out in accordance with these guidelines, and so Project Designs and Written Schemes of Investigation should include statements to this effect. Where relevant, named specialists should be included in such documents, and curators should ask for details of their relevant experience (published papers, reports, etc.), given that there is no formal means of accreditation.
Full use should be made of all available sources of information on the potential for using scientific dating effectively when planning archaeological projects. Chronology is the framework for understanding all archaeological sites and therefore the construction of reliable chronologies should form an integral part of the initial project specification. It should not be seen as a luxury.
4.2 Desk-based assessment
The purpose, definition and standard for desk-based assessment are given in CIfA (2020a). Specialists can contribute to desk-top assessments with information and evaluation of existing radiocarbon determinations from previous investigations, if they exist, and the potential for radiocarbon dating to contribute to the aims and objectives of the project. Such information can be used in order to help determine the location of evaluation trenches, and design appropriate sampling strategies.
4.3 Watching briefs
The purpose, definition and standard for watching briefs are given in CIfA (2020c). Radiocarbon dating undertaken on samples obtained during watching briefs would only be expected in exceptional circumstances (e.g. completely unexpected archaeological finds or deposits where artefactual evidence is absent).
The purpose, definition and standard for evaluations are given in CIfA (2014b). In order to understand the nature of the archaeological resource, evaluations are undertaken to inform decisions on planning and mitigation strategies.
In some situations, an evaluation might be the only intervention undertaken. Radiocarbon dating as part of evaluations can therefore constitute an important contribution to understanding the archaeological resource.
Samples can be submitted to provide range-finder dates to help assess the significance of the archaeological resource. For example, radiocarbon dating might be used to answer questions such as:
- What is the age of unexpected discoveries?;
- What is the age of deposits?;
- What is the date of archaeological remains without diagnostic material culture?
The tight time constraints often applicable to assessment following evaluations must not mean that the rigorous principles outlined for radiocarbon sample selection (sections 3.2.2–3.2.3) are ignored.
Large-scale geoarchaeological coring programmes (Historic England 2015a) undertaken to understand buried deposits often include radiocarbon dating of range-finder samples. The utility of information derived from simply obtaining age estimates for the top and bottom of cores needs to be carefully considered and justified. Such an approach should only be undertaken where it can demonstrably be shown to contribute to the specific aims and objectives of the project.
Sometimes projects do not proceed beyond evaluation. In these cases, radiocarbon dates from key deposits can contribute to priorities identified in regional, period or national research agendas.
Full excavation not only presents better opportunities for the recovery of samples for radiocarbon dating (e.g. Campbell et al. 2011), but more importantly enables better understanding their context. Samples should be retrieved and stored as outlined in section 3.2.1, and it is important that site staff are aware of the necessary protocols.
In selecting samples for radiocarbon dating, understanding of the taphonomic relationship between the datable material and the deposit from which it was retrieved is crucial (see section 3.2.2), and the site recording should reflect this. For example, recording articulating groups of animal bone in the field is an extremely cost-effective strategy (Baker and Worley 2019, 18).
An effective assessment for radiocarbon dating and chronological modelling can only be undertaken usefully once sufficient specialist assessments have been completed for the necessary information to be available: that is, the identification of the pool of potential samples for dating and the identification of the archaeological prior information that will be included in the chronological modelling (Fig. 9). This means that close co-operation among the radiocarbon/modelling specialist, site-director and other specialists is imperative to ensure the pertinent information is obtained.
For example, it is not sufficient simply to equate the survival of organic remains with the potential for radiocarbon dating. The presence of suitable short-life single entity samples from an assessment of a proportion of samples by a wood specialist/archaeobotanist provides the level of detail required to make an informed radiocarbon dating assessment. Thus, specific assessment of the suitability of samples for radiocarbon dating (e.g. environmental remains) needs to be requested from the relevant specialists (see Campbell et al. 2011, 8). Generally, the assessment for scientific dating will be amongst the last programmed within this phase of the project.
An exception is pre-screening bones for radiocarbon dating using the %N content of whole bone (Brock et al. 2010a; 2012) — a rapid and inexpensive method only requiring 5–10mg of bone — as an indicator of collagen preservation (see section 3.2.3).
As a minimum the following information is required by the specialist to carry out an assessment:
- brief account of the nature and history of the site,
- aims and objectives of the project,
- summary of the archaeological results,
- context types and stratigraphic relationships,
- sample locations,
- assessment reports from other relevant specialists, and
- an idea of the project timetable and budget.
The primary aim of the assessment will be to ascertain the potential of the samples to address the aims and objectives of the project. In order to maximise resources, close consultation is required with other specialists involved in the project (e.g. dating objects for intrinsic interest that will also contribute to answering broader chronological questions). It is therefore best if all radiocarbon dating is co-ordinated by a single specialist.
The assessment report should contain:
- aims and objectives of the project to which radiocarbon dating/chronological modelling can contribute,
- specialist chronological aims and objectives,
- a summary of potential samples,
- a summary of potential contexts to be assessed for samples suitable for dating,
- a statement of potential — how radiocarbon dating can contribute to site, specialist and wider research questions — simulation models if appropriate,
- recommendations for further work, including for full analysis if applicable, and
- the tasks, time and outline costings for future work (analysis and publication).
4.7 Post-excavation analysis
Radiocarbon dating and chronological modelling should have been planned and, as a minimum, outline costs provided while preparing the updated project design. The radiocarbon/chronological modelling specialist will need to work closely with other specialists (e.g., the site director, radiocarbon laboratories, environmental archaeologists, osteologists, material culture specialist, and others) at all stages of the analysis.
The major part of the Bayesian process (Fig. 9) will be undertaken at this stage of the project (see sections 3.2–3.5). It is essential that sufficient information and a timetable is available to enable the radiocarbon dating and chronological modelling programme to proceed in accordance with the overall project timetable. Forward planning is essential. Express radiocarbon dating is expensive and should not be used in compensation for inadequate project planning.
A full report should be provided in accordance with the guidance provided in section 3.6.
4.8 Dissemination and archiving
4.8.1 Historic Environment Record (HER)
In accordance with current best practice reports on any archaeological intervention, even if only an evaluation, should be deposited with the local HER as quickly as possible following their completion and added to OASIS. Chronological information could form a component of these reports, including radiocarbon results. Radiocarbon dates, together with the results from other scientific dating methods, should be recorded on Historic Environment Records.
Where possible the report (see section 3.6) should be included in the main body of the publication of a project (including in electronic supplementary information where this facility is available). But as it might not always be feasible to integrate the complete radiocarbon dating and chronological report with the full site publication, it might be appropriate for alternative publications in for example archaeological science, archaeological, environmental or other specialist journals.
All radiocarbon dating certificates and radiocarbon and chronological modelling reports should be included in the material deposited with the archival body, in accordance with their standards. For published overall guidelines on archive deposition see Brown (2011), Longworth and Wood (2000), Museums and Galleries Commission (1992), Walker (1990), and Archaeological Data Service (1997; 2011).
Samples suitable for further dating are usually included within the rest of the physical archive (e.g. bones, carbonised plant remains, etc.) and do not require specialist archiving. They should be packaged and stored as outlined above (section 3.2.1). The general lack of long-term storage for soil and sediment samples means that in some circumstances sub-sampling for cold storage can need to be considered, although this has potential complications for radiocarbon dating of waterlogged plant macrofossils (Wohlfarth et al. 1998).