Neville Agnew

Methodology, consetvation criteria and performance evaluation for archaeological site shelters

Abstract The many intersecting issues that arise when deciding whether to shelter an archaeological site should be approached using a values-based methodology, one that has demonstrated its validity arid practical worth in conservation over recent decades. Nonetheless, pitfalls abound in the decision-making process and in establishing effective conservation criteria which should be based principally on a thorough understanding of the threats to the resource and the specific deterioration mechanisms operating, with the objective of creating a shelter that will preserve the sites identified values. An aspect that has received almost no attention in the past is evaluation of a shelters performance, both qualitative and quantitative, in preserving the site. It is urged that this receive priority when establishing the conservation criteria during the initial phases of a sheltering project. Issues are illustrated from a range of diverse sites, including a number of published shelters. The paper first looks at the examples of the Laetoli (Tanzania) and Lark Quarry (Australia) trackway sites in the context of decision-making and conservation criteria, and then discusses two examples of evaluation: one quantitative, using an experimental shelter and the other discussing publications on a petroglyph site shelter.

Evaluation of the performance of a lightweight modular site shelter: Quantitative meteorological data and protective indices for the ‘hexashelter’

AbstractIn 1989, a temporary shelter was constructed to protect two mosaics in Cyprus. The structure was a prototype designed to cover certain categories of archaeological site. The concept behind the shelter was that it be lightweight, modular, easy to erect, relatively inexpensive compared with a conventional structure, and temporary if desired. The framework of the basic module has a zigzag profile and six sides: hence the name ‘hexashelter’. The hexagonal ‘footprint’ allows easy addition of modules by building laterally from anyone, or more, of the sides. It can also be built over somewhat irregular topography, and minimizes impact to the surface and to subsurface archaeology by using surface concrete anchor blocks as footings. The framework is aluminium tubing, covered with a fabric roof and with open-knit textile side panels. In 1991 essentially the same shelter was built at Fort Selden in New Mexico. The purpose of the second shelter was to evaluate its effectiveness. Quantitative data for the shel...

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.

A lightweight composite panel for the repair of cave roofs at the Mogao grottoes, China

AbstractErosion of the soft conglomerate of the cliff face at the Mogao grottoes of Dunhuang, China by windblown sand has thinned the rock of the roofs of many upper-level grottoes. In some cases, holes have formed; in others, the danger of roof collapse is imminent. To strengthen weakened roofs and to seal existing holes in an aesthetically acceptable manner, a lightweight, composite reinforcing and capping element was developed. The element, or panel, is made of a metal grid on a wood frame covered by geosynthetic materials, covered with sand and gravel. Potassium silicate is used to bind the sand and pebbles, thus presenting a natural appearance. Where holes exist, the interior is mud plastered on the metal grid. Experiments were conducted in the laboratory and in simulations at the Mogao grottoes to evaluate the concept and design prior to implementation. One field experiment was conducted on the ground to test cohesion and adhesion between the elements of the composite panel. The second experiment wa...

The GCI-WMF Iraq Cultural Heritage Conservation Initiative: Building Professional Capacity for Cultural Heritage Conservation and Management

Abstract One consequence of years of dictatorial regime, international embargo and war was isolation of the professional community responsible for the protection of cultural heritage in Iraq. This community was cut off from international debate concerning the development of methodologies and theories on the conservation and management of archaeological sites, historic monuments and districts. The Iraq State Board of Antiquities and Heritage (SBAH), the governmental body responsible for the nations cultural heritage, was also depleted of resources. Professionals could not access information, new technologies, such as the Internet and digital photography, and could not follow the international literature or discussions reflecting advances in practice. The Getty Conservation Institute and the World Monuments Fund partnered in late 2003 to form the Iraq Cultural Heritage Conservation Initiative (hereafter called the Initiative), to assist the SBAH to redevelop its professional and managerial capabilities. In meetings with the directors of departments of the SBAH in 2004, a plan was conceived to address the problems. A series of training courses was developed aimed at various categories of SBAHs staff, from directors of regional offices to archaeologists, engineers and surveyors. The training programmes covered technical topics such as the use of computers, geographic information systems (GIS), satellite imagery, digital photography, survey equipment (with equipment purchased by the Initiative and organisations such as UNESCO), and other issues related to the documentation, assessment of condition, and management of cultural heritage sites. A parallel activity is developing a GIS for the SBAH to maintain a national inventory of the archaeological and historic sites and monuments of Iraq — a tool that will also enable SBAH to record damage and threats to sites and to plan protective and conservation interventions. Due to the security situation in Iraq, development of the GIS has been reconfigured to be web-based since locating it in Baghdad was not practicable. The web-based GIS, dubbed MEGA (Middle East Geodatabase for Antiquities) has first been developed for Jordan given ready access to the country. The Jordanian Department of Antiquities (DOA) has been of great assistance in mounting training activities for Iraqi colleagues and has opened sites in Jordan for field exercises. This paper illustrates the activities of the Initiative and advocates similar projects not only in post-conflict areas, but as a matter of standard practice generally, since trained personnel and inventories can reduce the damage that war and civil strife so often inflict on cultural heritage.

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.

Reburial research: a conceptual design for field testing for the reburial of wall plasters and mosaic pavements

Abstract A reburial design concept for field testing for the in situ preservation of some of the most vulnerable of architectural substrates commonly found on archaeological sites is described. These substrates are earthen- and lime-based plasters, including those with painted and relief decoration, and mosaic pavements. A methodology is proposed for the evaluation of the performance of a selection of fill materials, intervention layers and moisture buffering layers, in on-ground simulated reburials. The guiding principles on which the design is based are that a stable, low-moisture environment provides optimal preservation for these substrate categories and that giving careful attention to the interface between the reburial fill and the substrate is of paramount importance. Two design models are described within the context of the reburial conditions required by these substrates and with a brief description of the reburial materials proposed for use. Integral to the test design is a comprehensive and systematic methodology for evaluation of the condition of the substrates before burial and after excavation at intervals of three, six and twelve years, and proven instrumental monitoring of thermal and hygral parameters throughout the testing period.

Improving Environmental Conditions in the Tomb of Tutankhamen

ABSTRACT The tomb of Tutankhamen in the Valley of the Kings, Egypt, one of the major attractions of the World Heritage Site of Ancient Thebes and its Necropolis on the West Bank of modern day Luxor, is today a destination for mass tourism. Visitors to the tomb increase relative humidity, elevate carbon dioxide levels, and encourage natural ventilation which facilitates entry of dust into the tomb. These conditions negatively impact the wall paintings and remaining artifacts in the tomb and create an uncomfortable environment for visitors. The deposition of dust inside the tomb collects on uneven wall painting surfaces, obscures their legibility and necessitates cycles of cleaning, which in turn leads to further damage. Developing environmental management strategies in the tomb to counter the effects of visitors and mitigate dust entry is an important component of the collaborative project between the Getty Conservation Institute (GCI) and Egypt’s Ministry of Antiquities (MoA) to conserve the tomb. These included implementation of a filtered-air supply and exhaust ventilation system to stabilize the interior microclimate and reduce dust in order to improve visitor comfort and contribute to the long-term preservation of the tomb.