Martha Demas

‘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.

Annotated bibliography on protective shelters for archaeological sites

Abstract The literature dealing with protective shelters for archaeological sites is meagre in relation to the number of shelters actually built or proposed, but nevertheless provides a critical source of information for practitioners and decision-makers about the range and types of shelters, their rationale and, infrequently, their performance. This annotated bibliography is a comprehensive overview of the existing literature on protective shelters (limited to English, French, German, Italian, Spanish and Portuguese) through the year 2000.

Monitoring through replication: Design and evaluation of the monitoring reburial at the Laetoli trackway site

Abstract How is it possible to monitor the condition of a site or artefact after it has been reburied? In the case of the reburial of the extremely fragile and remote site of Laetoli in Tanzania this problem was addressed by creating a replica reburial close to the site in 1995. The method and materials used to rebury the trackway are replicated in the monitoring trench, which thus provides a ‘window’ on the condition of the trackway. A series of samples and indicator objects of different materials placed in the trench are intended to provide an understanding of the burial environment over the long term. Additionally, triangular recesses with sharply defined edges were cut into the floor of the trench to allow determination of the mechanical stability of the tuff to deformation under the reburial overburden. The trench was lined with root-inhibiting Biobarrier® geotextile and then reburied in the same manner as the trackway; existing acacia trees at the edge of the trench were allowed to remain. In 1997 excavation of part of the trench was undertaken. Of particular interest was the fine detail of the topography of the floor of the trench and the effectiveness of the Biobarrier®. Geosynthetics showed no evidence of deterioration, but severe degradation of all wood samples without preservative chemical treatment and of indicator objects indicated a very aggressive environment. Many of the findings, such as survival or deterioration of the indicator objects, use of geosynthetics and the efficacy of Biobarrier®, have relevance to a broader understanding of buried environments.

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.

Strategies for sustainable tourism at the Mogao Grottoes of Dunhuang, China

Chapter 1: Introduction.- Chapter 2: Conceptual frameworks for managing visitor impact.- Chapter 3: The Mogao Grottoes of Dunhuang.- Chapter 4: The Mogao Visitor Study.- Chapter 5: Strategies for sustainable tourism.- Conclusions.

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.

Conceptual Frameworks for Managing Visitor Impact

The methodological framework of the Mogao study is based on the VERP (Visitor Experience and Resource Protection) model used by the U.S. National Park Service. The concept of “carrying capacity” has evolved in recent decades leading to VERP and other models for managing visitor impacts. The majority of scientists and practitioners who develop and apply these models come from a natural science background in which the application of the models has been aimed mainly at wilderness and natural heritage protected areas. Relatively little work has been done to apply these models to cultural heritage sites, especially to fragile and nonrenewable archaeological sites. The last section in this chapter explores the general characteristics of tourism, planning and administrative structures for cultural heritage in China, which differs from Western contexts where these models are applied.

The Mogao Grottoes

The history and significance of Mogao are developed in this chapter. For more than a 1,000 years Dunhuang had thrived as an outpost guarding the westernmost regions of the empire, protecting trade and encouraging the exchange of goods and knowledge between the heartland and regions to the west. Buddhism flowed along the Silk Road oases into China proper and beyond. During this period artisans constructed the caves along the mile of cliff face. The decorated caves of Mogao are among the world’s most important sites of Buddhist art and afford an unparalleled record of a millennium of Chinese wall painting and sculpture, depicting not only the religious practices of the period between the fourth and fourteenth centuries, but also life, customs, costumes, music, agriculture, and a wealth of historical information of the times. Management of the grottoes dates back to the 1940s when a group of young archaeologists and artists began the work of preserving, studying, and documenting the site. In 1999 the Dunhuang Academy began their master planning process following the methodology of the China Principles. Out of this process visitor management and, specifically, the urgent need to determine the relationship between visitation to the caves and deterioration of the wall paintings emerged as a priority.

The Mogao Visitor Study

The first phase of the methodology of the Mogao visitor study involved identifying the main issues impacting the site, indicators to monitor change and the desired conditions for the site, leading to defining limiting conditions for visitation. Within this basic framework a major research and assessment component was developed to address the issues impacting the grottoes and visitors. The components of the research, the questions they were designed to answer, the methods used, and the results achieved constitute the core of the study. The research design required, foremost, investigation of the causes and mechanisms of deterioration of the wall paintings and the impact of visitation on cave microenvironments to establish the link between visitation to the caves and salt-related deterioration due to high humidity. The research strategy integrated analytical investigations in the laboratory; extensive environmental monitoring and research; field testing; and assessment of condition and visitation potential for 112 priority caves. It serves as a model for investigative research on the impact of visitors on deterioration and high carbon dioxide in confined spaces.

Strategies for Sustainable Tourism

Emerging out of the first phase of the Mogao Grottoes visitor study were limiting conditions for visitation, from which the strategies for sustainable tourism to the grottoes were developed in the second, response phase of the methodology. To achieve highest visitation requires operational changes that are challenging, but management tools (computer simulation models, reservation, and visitor management systems) allow site managers to create tours responsive to changing conditions and varied visitation demands on a daily or seasonal basis. Management actions that respond to monitoring include simple methods as well as technologically sophisticated ones such as automated monitoring stations that alert staff to harmful humidity and carbon dioxide levels. To compensate for a potentially diminished visitor experience during peak visitation, interpretive programs, varied exhibitions, films, and virtual cave tours have been developed and a new Visitor Center constructed outside the site’s boundary. Such programs, in addition to new presentation, lighting, and interpretation of the cave interiors, will diversify the visitor experience and dovetail with changing visitor demographics and patterns of travel that are already making themselves felt in China.