The use of geosynthetics for archaeological site reburial

Abstract

Applications of geosynthetic materials in reburial practice include geotextiles for separation, filtration and protection (cushioning); geomembranes and geosynthetic clay liners for infiltration control; geonets and geocomposites for sub-surface drainage; and geocells for erosion control. Mechanically stabilized earth reinforcement using geocells, geogrids and geotextiles can also provide substantial benefits for reburial projects by reducing lateral earth pressure against backfilled structures. Other aspects of modern geotechnology that may be useful for reburial projects include micro-piles and soil nailing for foundation and excavation support and evapotranspirative capping technology to establish the depth of soil cover required to isolate a structure or artefact from moisture and temperature fluctuations. Optimal application of these geotechnologies requires an understanding of the basic engineering principles associated with their implementation, as well as knowledge of the factors influencing archaeological site preservation.     

Reburial in the context of development: Approaches to reburial in the English planning process

Abstract

Rescue archaeology in England is now firmly embedded in the planning process, following the introduction by the UK government of Planning Policy Guidance Note 16 in 1990 (PPG 16; Departmentof the Environment. Planning Policy Guidance Note 16 — Archaeology and Planning. HMSO, London (1990)). The basic premise of PPG 16 is a strong preference for in situ preservation of nationally important archaeological remains. This often includes reburial of archaeology prior to construction activity, once it has been exposed in test-pitting (‘evaluations’) or full excavation. Reburial strategies are often prepared by civil engineers and there appears to be an overemphasis on consideration of the potential physical impacts on the archaeology. These strategies usually include the use of geotextiles and sand, or other graded material, chosen for its particular particle size/shape characteristics. A greater awareness of the chemical and physical characteristics of a burial environment is now required to ensure that reburial is effective. Archaeologists and conservators are beginning to consider both the natural and, increasingly, the ‘man-made’ (industrial, domestic and agricultural) changes to the soil chemistry of an archaeological site. More use needs to be made of the potential information ‘locked up’ in the artefactual material retrieved from evaluations and excavation nearby. An assessment of the degree of preservation of material should be an integral component for the design of a reburial strategy.     

The Australian Historic Shipwreck Preservation Project: In situ Preservation and Long-Term Monitoring of the Clarence (1850) and James Matthews (1841) Shipwreck Sites

Increasingly, archaeologists are opting for on-site examination, reinterment, and in situ preservation of underwater cultural heritage sites as the first option in the management of sites at risk, as opposed to the more traditional excavation, recovery, conservation, and display/storage methods. This decision will inevitably be based on significance assessment, degree of perceived risk, and resourcing issues. However, long-term monitoring must become an integral part of these management programmes in order to quantitatively evaluate the effectiveness of the in situ preservation techniques employed. In 2012 the Australian Historic Shipwreck Preservation Project (AHSPP) was awarded a large Australian Research Council (ARC) Linkage Grant, enabling ten partner organizations and three Australian universities to collaborate in one of the largest multi-organizational maritime archaeology projects to be undertaken in Australia to date. One of the major aims of the project is to develop a protocol for the excavation, detailed recording and reburial of significant shipwrecks under threat, fostering a strategic national approach for the management of underwater cultural heritage (UCH) sites at risk. Two historically significant shipwreck sites that are considered under threat were chosen for this longitudinal comparative study — the Clarence (1850) located in Port Phillip Bay, Victoria; and the James Matthews (1841) which lies in Cockburn Sound, Western Australia. Both sites have been preserved in situ using two very different but innovative remediation strategies. More importantly, long-term monitoring programmes have been implemented on both sites, which will characterize changes in the reburial environment and the effect on the reinterred materials. In this way, the efficacy of both in situ preservation techniques will be systematically tested, providing a comparative analysis of practical protocols for the long-term protection and management of underwater cultural heritage.     

Temporary site protection for earthen walls and murals at Çata1höyük,Turkey

Abstract

The exposure of earthen architecture at archaeological sites presents tremendous difficulties both during and after excavation. While it is the intent of most reburial programmes to stabilize exposed structures against the long-term effects of loss of pressure and fluctuations in moisture, relative humidity and temperature, reburial does not easily afford practical protection against immediate damage caused during excavation. At the Neolithic site of Çata1höyük in Anatolia, Turkey, a phased programme to integrate the excavation and conservation of the site was developed. This included emergency stabilization and protection of the mud brick walls, plasters, mural paintings and relief sculpture, both during and between excavation seasons. One component of this programme included the development of a temporary perlite-vermiculite protection system.     

‘Site unseen’: the case for reburial of archaeological sites

Abstract

The decision-making process for managing and conserving archaeological sites is increasingly accepted as being driven by a thorough assessment of values, physical condition of the resource and the management context. Reconciling the results of these assessments, which may point in different directions, to arrive at a decision that is most appropriate for the resource can be a complex process. When reburial (also referred to as backfilling) is being considered as an option for the preservation of an excavated site (especially long-term reburial), there are particular opportunities and constraints and a host of considerations (stakeholder, technical and management) that need to be taken into account if the values of a place are not to be compromised and stakeholders alienated. For, however beneficial reburial may be from a conservation perspective, it is generally viewed with scepticism or disfavour by those with legal authority over a site, and by those stakeholders who want access to the site for study, education or money-making. This paper examines the rationales for reburial, as well as the objections to it, and puts forth a decision-making model for reburial interventions that takes into consideration stakeholder, technical and management needs.     

A Critical Analysis and Philosophical Review of ‘Rapid Reburial’: the Clarence project

In 2012, Australian cultural heritage practitioners and conservation scientists collaborated on a national underwater cultural heritage (UCH) reburial project, known as the Australian Historic Shipwreck Preservation Project (AHSPP) funded by the Australian Research Council. This resulted in the excavation, documentation and reburial of the ‘at risk’ shipwreck Clarence. Following the excavation, the site and associated artefacts were reburied and subsequently covered by shade cloth and finally, with polyvinyl chloride (PVC) tarpaulins. After completion of the in situ reburial, a number of critical issues were put into sharp relief including: what constitutes the accurate identification of a site as being ‘at risk’; and the implications of ‘rapid reburial’.     

Chaco Canyon reburial programme

Abstract

Chaco Culture National Historical Park in northwestern New Mexico contains a wealth of archaeological resources, including 150 large earth and masonry structures under active management and preservation. In response to loss of original fabric from exposure over the last 100 years and more, as well as from continuous cycles of maintenance and repair, an extensive and long-term reburial programme was embarked upon in the late 1980s. The overall context of the site and the decision to undertake reburial as a principal conservation strategy is described in Part I of this paper. Part II provides a summary of the results of partial reburial at Chetro Ked, one of the ‘great houses’ of the canyon, in which protection of original timber was the main objective. Most of the wood at Chetro Ked could be covered only by a shallow overburden of soil, necessitating a specialized reburial design and materials to exclude moisture. Recent evaluation of the efficacy of the wood reburial was undertaken. Problems and shortcomings that were identified have led to re-design of part of the reburial and more careful attention to quality control during the intervention, as well as to selection of more appropriate geosynthetic materials. Additional monitoring techniques have been developed to allow direct withdrawal of samples of wood for assessment of deterioration.     

Reburial of shipwrecks in marine sediments: a long-term study on wood degradation

Historical shipwrecks in marine environments are continuously decomposed by wood-degrading organisms, adapted to this specific environment. To protect the wrecks from degradation and to preserve the unique remains for future generations, reburial of wrecks using various covering materials has been suggested as a long-term preservation method. The following experiment was carried out to study the bio-protective effect of sediment. Sound oak, pine, and birch samples were buried above and within marine sediment in Marstrand harbour, and retrieved for analysis after 6, 12, 24, and 36 months. Macroscopic as well as light-microscopic examinations were carried out on each occasion. Marine borers (shipworm, Limnoria), soft rot and tunnelling bacteria were wood degraders immediately above the seabed; soft rot, tunnelling bacteria, and erosion bacteria were active 10 cm below the seabed; erosion bacteria were the only degraders at a depth of 43 cm below the seabed. The wood species had different durability towards the decay agents. After 3 years, wood samples above the seabed were totally decomposed, whereas wood was highly protected at 43 cm depth in sediment. In the sediment, decay decreased significantly with depth of burial. The results suggest that reburial of shipwrecks in marine sediment can be recommended as a simple and efficient method for long-term preservation of the wooden cultural heritage.     

In Situ Preservation and Monitoring of the James Matthews Shipwreck Site

Abstract

Over the past few decades, the archaeological community has been moving away from the more traditional methods of excavation and recovery of underwater cultural heritage towards a less intrusive management approach, essentially involving the preservation of sites in situ. This trend has been politically galvanized in Article 2, point 5 of the Convention on the Protection of the Underwater Cultural Heritage (), which states that ‘The preservation in-situ of underwater cultural heritage shall be considered as the ?rst option before allowing or engaging in any activities directed at this heritage’. Over the years, a number of different remediation strategies have been utilized in order to protect underwater cultural heritage sites in situ, and most of the techniques or combinations thereof involve reburial of sites. Reburial may be an appropriate means of stabilizing and decreasing the deterioration rate of a site, however, there needs to be a holistic approach to the study of the environment, before and after reburial, to gain a full understanding of the changes that are occurring on the site and determine the effectiveness of the technique.

In early 2000, the James Matthews, a copper-sheathed, wooden-hulled vessel wrecked in 1841 south of Fremantle, Western Australia, was identi?ed as being under considerable threat from increased site exposure due to a combination of natural near-shore sedimentary processes and industrial activity in the immediate area. An extensive on-site conservation survey was carried out to establish the state of preservation of the wreck and provide information regarding the physico-chemical and biological nature of the environment prior to the implementation of any mitigation strategy. In 2003 it was con?rmed that further exposure of the site was occurring and devising a management plan was of paramount importance.

Since this time a number of different reburial techniques have been trialled on the site and these include sand bags of differing material composition, polymeric shade cloth, arti?cial sea grass mats made from polyvinyl chloride bunting, and the use of interlocking medium density polyethylene ‘crash barrier’ units in a cofferdam arrangement to con?ne deposited sand. The geological, physico-chemical, and microbiological changes in the burial environments have been monitored over this time. Furthermore, the broader scale, near-shore sedimentary processes affecting the site are being assessed in order to establish the reasons behind the continuing sediment loss. In situ preservation of the iron ?ttings by cathodic protection has also been included in these ?eld trials. In this paper the results from these experiments will be summarized. This information will be used to ?nalize the design of the full-scale in situ preservation strategy for the site and assist in establishing a post-reburial monitoring programme that will measure the success of the adopted remediation technique.     

Some considerations for the reburial of painted lime stucco façdesin the Maya region

Abstract

The conservation of Maya stucco façadesin humid tropical conditions poses significant challenges. Professionals in the region consider that reburial is one of the most easily accomplished and cost-effective conservation options; and reburial of modelled and painted lime plaster façades, in conjunction with the construction of exposed replica façadesoverlying the reburied originals, has been or is being considered as a preservation strategy at a number of sites in the region. This is illustrated by two case studies from Belize and one from Guatemala. However, more research is needed to fully understand the benefits and risks of reburial, and to determine the optimal conditions and techniques specifically suitable for wet tropical climates. The range of issues that must be considered for reburial of stucco façadesin this region include their conservation needs in relation to the susceptibility of ancient materials to climatic conditions, management issues such as visitor and interpretation needs and the problem of looting in the region, the feasibility of solutions in relation to available resources, choice of methods and materials used in interventions, and the impact of reburial on the significance of a site, amongst others.     

What Happened in Neiden? On the Question of Reburial Ethics

The Neiden Case reburial from Finnmark, North Norway, marks the closure of a process initiated with a controversial excavation in 1915 when 94 skeletons were brought to University in Oslo. The skeletons formed part of a monumental work in physical anthropology by the Norwegian anatomist Karl Emil Schreiner concluding that the Sámi belonged to a somewhat infantile proto-Mongolian race. There is little doubt about unethical aspects of the excavation as well as the exceedingly dubious character of racial research on the Sámi prior to the Second World War. However, considering the handling of the case, opposing facts and opinions, lack of knowledge and other uncertainties, ethical implications seem far from obvious. With regard to the dead themselves the reburial may even be considered unethical. This paper emphasizes the complexity of the ethics of reburials with particular attention to the dead, their graves and belongings.     

Reburial research: preliminary field experiments at Fort Selden

Abstract

Preservation through reburial is an effective strategy for cultural sites, and information exists that identifies broad categories of fill type, materials and the below-ground physico-chemical and biological conditions that favour survival of cultural artefacts. This apart, relatively little systematic research and testing has been undertaken on the reburial of archaeological materials under alternating wet—dry conditions, which pertain in many areas of the world where rich archaeological resources exist that are also a focus of excavation. Preliminary field research and testing was undertaken at the site of Port Selden, New Mexico, over an approximate eighteen-month period in 1995–1996 as a precursor to intended longer-term experiments. The ultimate objective was to determine optimal conditions for designed reburial interventions of archaeological materials. Testing was done in pits and on the ground and utilized a standard artefact comprised of adobe and lime as well as several indicator materials (wood, textile, brass). The problems associated with the design of the experiment, instruments and monitoring are discussed, as well as findings relevant to current practice and future testing. The eighteen-month preliminary testing itself followed an earlier (1988) reburial test at Fort Selden in which adobe walls were buried. The results of this test wall experiment are also included here, as they are pertinent to an understanding of the behaviour of earthen architectural materials in the reburial environment.     

The RAAR Project — Heritage Management Aspects on Reburial After Ten Years of Work

Abstract

The general purpose of the international reburial project, Reburial and Analyses of Archaeological Remains (RAAR), is to evaluate reburial as a method for the long-term storage and preservation of waterlogged archaeological remains. Since 2001 material samples have been buried, retrieved, analysed systematically, and the results reported.

RAAR has mainly focused on the degradation of materials commonly encountered on archaeological sites, and on environmental monitoring techniques in order to determine what type of material can be reburied and for how long. The project has concluded that a heritage institution could provide short- or long-term curation for its archaeological archive by using reburial depots provided they are set up according to guidelines and restrictions stipulated by the RAAR project.

However, there are management and legal aspects that need to be discussed and resolved before each reburial project. Actual reburials that have been carried out so far are often a solution to emergency situations and lack collection and management policies. The questions ‘what’, ‘why’, and ‘for how long’ have been forgotten and need to be addressed. The legal protection of a reburial site is also important. This paper discusses these aspects and their consequences and highlights possible differences in approaches between the countries involved in the RAAR project.     

Reburial and protective covering of ancient mosaic pavements: The experience of the conservation department of the Israel Antiquities Authority

Abstract

Four case studies are presented illustrating different attempts to protect excavated ancient mosaics by reburial or protective covering, with varying degrees of success, at three archaeological sites in Israel: Tel Itztaba, a site excavated between 1991 and 1994 where planning for reburial at the outset of the excavation could have prevented considerable losses; Khirbet Minya (Horvat Minim), a site excavated in the 1930s, reassessed after four years of reburial; the Promontory Palace at Caesarea Maritima, a site excavated in 1978, partially destroyed by the sea, reburied and regularly monitored since 1994; and an experimental test site at Caesarea Maritima. These examples demonstrate the importance of planning, monitoring and maintenance for successful reburial, and allow an assessment of which materials and methods performed better than others.     

Relevance of soil biology and fertility research to archaeological preservation by reburial

Abstract

This paper discusses how soil biological information can help to improve understanding of, and possibly inform decisions about, preservation of organic archaeological remains by reburial. A brief summary of the properties of the soil biological community is followed by an outline of results from recent biological investigations following the recovery of archaeologically relevant materials that had been buried for thirty-three years in one of the experimental earthworks in England UK. Examples from the soil biology and fertility literature are discussed to illustrate the effects of fluctuations in soil wetness and aeration, and of nitrogen availability on decomposition. Finally, the impact of soil handling and physical disruption on biological processes in soil are discussed, as they influence whether soil functions can be restored at a reburial site once the archaeological resources have been ‘protected’ beneath.     

The reburial of mosaics: an overview of materials and practice

Abstract

A significant proportion of the literature on the reburial of archaeological sites concerns mosaics. These publications reveal that a variety of materials have been used for mosaic reburial, including specialized fill and separation layers, from the early 1980s onwards. Although reburial practice often demonstrates an ad hoc and indiscriminate use of fill and separation materials, or the following of trends and anecdotal information favouring certain materials, knowledge of their characteristics is very important in developing an appropriate technical design for reburial of mosaics. The materials most commonly employed in mosaic reburial practice, including geotextiles, are reviewed and an assessment of their positive and negative characteristics within a reburial design is provided. Recent but limited laboratory and field testing, monitoring and evaluation of reburial interventions have begun to provide preliminary evidence about the behaviour of these materials, indicating which ones are most appropriate and how they should be utilized to best advantage. However, their selection and use remains uneven, and positive results continue to be as much a function of adequate maintenance as proper design and execution.     

Reburial and Analyses of Archaeological Remains in the Marine Environment — Investigations into the Effects on Metals

Abstract

The treatment and long-term storage of recovered cultural material from underwater heritage sites is becoming less cost effective, and reburial of archaeological sites and the associated artefacts in the marine environment is becoming increasingly common practice in managing the submerged cultural resource. Following recent large-scale underwater archaeological excavations in Marstrand harbour, Sweden, the majority of recovered finds were reburied in defined trenches in the harbour sediment. Subsequently, the Studio of the Western Sweden Conservators in conjunction with the Bohus County Museum initiated a fifty-year research project to evaluate reburial as an appropriate method of preserving waterlogged archaeological artefacts in the long term. The research project, entitled ‘Reburial and Analyses of Archaeological Remains’, was launched in 2002 and consists of six sub-projects. The main aims of these sub-projects are to analyse the extent of deterioration of the most common material types found on underwater archaeological sites, assess the stability of packing and marking materials used in archaeological documentation, and monitor the reburial environment.

The aim of the metals sub-project is to investigate the short- to long-term corrosion behaviour of metals buried in the marine environment by examining the deterioration of reburied and exposed modern metal coupons and eventually compare these results to the analysis of actual shipwreck artefacts. The environmental monitoring sub-project is designed to complement the other sub-projects by assessing the physico-chemical changes occurring in the reburial environment over time and the effect on the deterioration of the different reburied material types. In comparing the results obtained over the past seven years from both the metals and monitoring sub-projects, it should be possible to more accurately evaluate the effectiveness of reburial as a long-term in situ preservation strategy for metallic archaeological remains.     

Caring for the dead? An alternative perspective on Sámi reburial

This article is an effort to critically discuss Sámi repatriation and reburial practice based on the analysis of five repatriation cases. Since the seminal repatriation (and burial) of the skulls of Somby and Hætta in Gávvuonna/Kåfjord in 1997, and the more recent reburial of 94 skeletons in Njauddâm/Neiden in 2011, a precedent seems established in Norway that allows the unconditional reburial of all Sámi human remains from collections and excavations. This inevitably poses a serious challenge to research on Sámi human remains and the Sámi past. It is argued that what is important is not research, but that Sámi are allowed to decide for themselves how they wish to care for the dead. Rather than argue according to the adversarial pro-research or pro-reburial viewpoints, this article will take a closer look at how the dead, and their associated material remains, are cared for during Sámi reburial. As will be argued, the care for the material side tends to be neglected and therefore raises an ethical question regarding this practice.     

Conservation of archaeological mosaic pavements by means of reburial

Abstract

In a burial environment ancient mosaic pavements are subject to a variety of mechanisms of deterioration, both physical and chemical. However, many pavements have survived, sometimes in exceptional condition. Additionally, some mosaics that have been discovered in recent times and reburied as a means of protection have also been well preserved. This indicates that reburial can be an effective means of preventive conservation and a viable response to the need for conservation of exposed mosaics on many archaeological sites. For reburial to be successful, risks to the mosaic must be accurately appraised and the design of the reburial must be well specified, following a rigorous conservation methodology.