Complications and Effectiveness of In Situ Preservation Methods for Underwater Cultural Heritage Sites

Abstract

Underwater Cultural Heritage (UCH) as an outstanding division of the cultural heritage of humanity appears to be crucial and complicated when more general issues regarding preservation and conservation are raised. The essence of in situ preservation should be equally discussable for any kind of archaeological remains; on land or underwater.

There is a long history of different methods and concepts of intervention in a variety of sub-aquatic archaeological sites; from shipwrecks to submerged settlements. This paper will present an introduction to different techniques and theories of preservation and conservation of underwater cultural and archaeological sites since this kind of heritage has scientifically been explored and studied. A range of different preservation methodologies, from total or partial transference inland, to preservation underwater, will be compared; the advantages and disadvantages of each option will be highlighted. Different examples of international best practices will be illustrated. Different types of in situ conservation/protection will be explained and categorized. Furthermore, there will be a focus on the UNESCO Convention of 2001 on Conservation and Preservation of UCH, where the in situ conservation option has been recommended.

Moreover, the technical issue for preservation of UCH sites, either in situ or after displacement, will be explained. The implication of relocation for different sorts of sites and materials will be argued; for example, cases where some sites, such as shipwrecks, would more easily be displaced compared with submerged settlements, villages, or ports.

Finally, by stressing that the state of ‘being underwater’ makes many sites qualified to be regarded as UCH, the in situ preservation approach will prevail that this state is maintained.     

Exploring preferences and non-use values for hidden archaeological artefacts: a case from Denmark

This paper presents a choice experiment study of a proposed wetland restoration project which aims to preserve archaeological artefacts from Stone Age villages which are presently buried within the topsoil. Wetland restoration can avoid destruction of the artefacts due to agricultural cultivation and drainage, and in addition improve biological diversity and recreational opportunities. The results indicate that even though the artefacts are not visible or usable for the population of today, but may contain information and potential value for future generations, the strongest preferences displayed is for ensuring permanent protection of archaeological artefacts, rather than biological diversity and recreational opportunities. The results are discussed in relation to the Prospect Theory: people value a loss of cultural heritage higher than a gain of new cultural goods or services. This insight is of general interest to cultural economics and cultural policy, especially with respect to heritage protection.     

The ISCR Project ‘Restoring Underwater’: An Evaluation of the Results After Ten Years

Abstract

The project ‘Restoring Underwater’ launched and conducted by the Underwater Archaeology Operations Unit of the Istituto Superiore per la Conservazione ed il Restauro (ISCR, Rome, Italy) is aimed at the study and the experimentation of instruments, materials, methodologies, and techniques for the restoration, conservation, and in situ display of ancient submerged artefacts. The project commenced in 2001 with the restoration of the vivaria of the Roman villa of Torre Astura (Nettuno, Rome), since 2003 the main subject of researches has been the submerged archaeological site of Baiae (Naples, Italy), where, over the years, the restoration of sectors of certain buildings in the protected marine area has been carried out: the Villa con ingresso a Protiro, the Villa dei Pisoni, the Via Herculanea, and the Building with porticoed courtyard near Portus Iulius. In 2007, in 2009, and in 2010 three new archaeological targets have been added to the research: a group of nine cast iron cannons discovered offshore the coast of the Marettimo Island (Sicily, Italy), the Roman wreck carrying a load of sarcophagi discovered off the coast of San Pietro in Bevagna (Taranto, Italy), and the traditional fishing boat recently discovered off the cost of Martana Island (Bolsena Lake, Italy).

The purpose of this paper is to sum up the work in progress and the results of these ten years of the project. The paper will shows as the conservation and museum display in situ of underwater heritage must not just be considered an opportune choice but may in itself provide a strong stimulus for experimenting new materials and technologies as well as representing a factor in the socio-economic development of the communities concerned, as shown by the example of Baiae.     

A Framework for Managing Diver Impacts on Historic Shipwrecks

Shipwrecks are becoming increasingly popular and, therefore important attractions for recreational scuba divers. Divers’ usage of these sites has the potential to create a range of adverse impacts on their cultural heritage values. Impacts associated with recreational scuba diving include boat anchor and mooring damage, impairment of site integrity and stability, the effects of intentional and unintentional contact with shipwrecks and artifacts, as well as divers’ exhaled air bubbles coming into contact with shipwrecks. While these consequences may not present a major threat in comparison to other human impacts, such as fishing activities, extractive industries or commercial salvage, their cumulative effect can be significant, particularly at sites where visitation levels are high. Unlike natural events such as storms, diver impacts can be controlled and managing these impacts is an important component of a heritage management strategy for any site. Heritage managers face the difficult challenge of, on the one hand, balancing divers’ access to important underwater cultural heritage sites, and on the other hand, protecting these sites. This paper outlines the causes and nature of potential recreational diver impacts on shipwrecks, briefly describing a range of management approaches that can mitigate such impacts, and presents a framework for the management of diver impacts on cultural heritage values of historic shipwrecks. The framework is designed to assist managers in deciding on appropriate management actions and priorities for particular sites.     

An Analytical Methodology for the Study of the Corrosion of Ferrous Archaeological Remains in Soils

Abstract

In the context of the cultural heritage, a methodology based on ?eld and laboratory approaches is developed for studying the long-term corrosion of iron. Moreover it has been adapted to the study of archaeological artefacts buried in anoxic soils in the speci?c case of in situ preservation. The environmental parameters are determined on the archaeological sites and artefacts are collected and characterized using complementary multi-scale techniques. Moreover, laboratory experiments are performed to locate the reaction sites inside the corrosion layer and to identify its electronic properties. The results allow estimation of a low corrosion rate for iron buried in an anoxic soil (under 2 μm/year) and the proposal of a mechanism based on a decoupling of the anodic and the cathodic sites. Then a diagnosis of the alteration state of the samples is established.     

Archaeology of the Ljubljanica River (Slovenia): early underwater investigations and some current issues

Abundant archaeological evidence and specific geomorphologic features make the upper course of the Ljubljanica River running through Ljubljana Moor (Slovenia) one of the most interesting rivers in Europe. Roman bronze vessels and iron weapons found by chance in the Ljubljanica at Vrhnika, the ancient Nauportus, led the director of the Provincial Museum in Ljubljana, Karel Dežman, to devise a large scale plan for an underwater survey of the riverbed. This, one of the first modern research projects of underwater archaeology was executed in 1884 with the help of divers from the Austro-Hungarian naval base in Pula. Investigations by the Group for Underwater Archaeology and the activities of amateur divers from 1979 onwards revealed distinctly structured distributions of underwater finds on several sites in the upper course of the river indicating possible sacred places with votive offerings and funeral sites, as well as other non-ritual concentrations.     

Survey Results from Lagos Bay,Portugal

The Projecto de Carta Arqueológica Subaquática do Concelho de Lagos (PCASCL) aimed to locate, identify and protect existing underwater cultural heritage within the district's coastal area. This project was based on a five‐phase methodology which included archival research, assessment, survey and conservation. PCASCL resulted in the discovery of five shipwrecks and several artefacts which were added to the Portuguese archaeological record. This also led to the development of a secondary project which focused on one of the five shipwrecks as well as proposals for an underwater archaeological park in Lagos.     

Showcasing Maritime Heritage Artefacts for the Benefit of the Tourist Industry in Malaysia

Conservation in urban areas is an active issue, but in remoter areas historical remains are neglected by both public and government. Conservation of maritime archaeological sites is fast becoming important elsewhere. Acknowledging the importance of conservation for other types of historical sites, this paper addresses the need for conservation of the as-yet-unknown number of maritime archaeological sites in Malaysia. This will take time and continuing effort. Malacca Maritime Museum is a case-study, built specifically for showcasing artefacts from shipwrecks. The first such museum in Malaysia, it has benefited tourism as well as preserving objects and educating the public.
© 2005 The Nautical Archaeology Society     

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.     

Some Aspects of the Bioerosion of Stone Artefact Found Underwater: Significant Case Studies

Abstract

Within the framework of the project Restoring Underwater started in 2001, the ISCR Marine Biology sector with the ISCR Underwater Archaeology Operation Unit has begun a study of the deterioration of stone artefacts exposed to marine environments (Torre Astura – Nettuno; Baiae – Naples). These studies have allowed to better understanding the factor of degradation by biological, mineralogical, and petrographic analyses and to develop measures for the protection in situ of cultural heritage. Based on what was recorded, usually the bioerosion presents various degrees of gravity: limited and sporadic damage or very serious alterations. Depending on their chemical composition, the artefacts proved to be particularly susceptible to the action of corrosion exercised by perforating animal and plant organisms.

This phenomenon becomes more significant in the case in which the artefacts remain exposed and in the same position for a long period of time. It is possible to confirm that the combined action of attack from clionides (sponges) and bivalves can lead, over time, to the total destruction of portions of the artefact (macroboring). As well as these more macroscopic types of damage, there was evidence of the widespread presence of microscopic bioerosion (microboring), caused by autotrophic and heterotrophic microorganisms, visible only through SEM observations, which, despite not creating large chambers, progressively undermine the resistance of the stone and facilitate the development of other biodeteriogens. This paper will be focused on the characterization of the bioerosion observed on different artefacts: the roman statues discovered underwater in the Grotta Azzurra, Capri and in the Campi Flegrei area (Naples –Italy), and the marble sarcophagi that are still on the seabed of San Pietro in Bevagna (Taranto – Italy).     

Our Privilege and Co-responsibility in the Protection of the Underwater Cultural Heritage

Mexico’s National Institute of Anthropology and History established an ethical program for the protection and research of the country’s underwater cultural heritage (UCH). Its Vice-Directorate of Underwater Archaeology trains archaeology and conservation students, participates in national and international initiatives regarding UCH, and develops multidisciplinary projects in maritime and continental waters. During negotiation of the UNESCO Convention, the Latin American and Caribbean Group united in a strong voice and contributed to its adoption in 2001; in 2006, Mexico ratified the Convention. This article highlights Mexico’s adoption of the 2001 UNESCO Convention as a case study, to stimulate all countries to ratify the convention and to cooperate in protecting the world’s UCH.     

Mexico: A Leader in Ratification of the UNESCO Convention on the Protection of the Underwater Cultural Heritage

Mexico’s National Institute of Anthropology and History established an ethical program for the protection and research of the country’s underwater cultural heritage (UCH). Its Vice-Directorate of Underwater Archaeology trains archaeology and conservation students, participates in national and international initiatives regarding UCH, and develops multidisciplinary projects in maritime and continental waters. During negotiation of the UNESCO Convention, the Latin American and Caribbean Group united in a strong voice and contributed to its adoption in 2001; in 2006, Mexico ratified the Convention. This article highlights Mexico’s adoption of the 2001 UNESCO Convention as a case study, to stimulate all countries to ratify the convention and to cooperate in protecting the world’s UCH.     

The Shipwrecks of Xlendi Bay,Gozo, Malta

Xlendi Bay, Gozo, Malta, is a rich underwater site. It was discovered in 1961 by British Navy divers on a training mission. Since then, a significant number of artefacts has been retrieved but not well studied. This paper summarizes a recent detailed study of the archaeological material and describes five amphora types that have not yet been identified. It also takes deep‐water surveys that have recently been conducted by various teams into consideration.     

The role of the Italian Central Institute of Restoration in the field of underwater archaeology

In 1987, given the importance and complexity of the correct recovery and conservation procedures for underwater archaeological finds, an Underwater Archaeological Operations Unit was set up within the Italian Central Institute for Restoration. This Unit is made up of archaeologists, conservators, biologists and chemists, all of whom are underwater experts. It provides consultancy services and scientific and technical assistance for problems relating to the recovery, conservation, protection, and restoration of underwater archaeological heritage at the request of the Archaeological Superintendents. Great attention is paid to the professional training of underwater conservators. Specialized courses in the conservation of materials of underwater provenance are organized as part of its programme. This paper illustrates some of the main initiatives both in the restoration of archaeological objects and in training, in which the Institute has been involved, since the Underwater Unit was created.     

The HMS Swift shipwreck: The development of underwater heritage protection in Argentina

Abstract

The aim of this article is to evaluate, with a critical perspective, the legal framework for heritage protection in Argentina, viewing it within an international context and focusing on the HMS Swift shipwreck – sunk in Puerto Deseado (Santa Cruz province) in 1770 – as a case study. Moreover, some initial proposals for a management plan are presented as a first step in thinking about the challenges of preserving underwater sites in Argentinian Patagonia.

Through this analysis some interesting points are outlined, including the reasons that make the Swift shipwreck a leading case in Argentina. It is the first interdisciplinary underwater archaeology project in the country comprising archaeologists who are also divers; it is supported by national authorities; and it is the first project of its kind to give underwater archaeologists experience in dealing with archaeological research and preservation in an environment of multiple conflicting interests.

The international relevance of the Swift case relies on the nature of underwater cultural heritage as an international resource. The project's history is located in an international setting, derived from ihternational trade and communication, in which many ships and their contents have been lost far from their origin or destination. At a national level the Swift is a wreck with significant historical and cultural value. It is in a unique state of preservation and its location near to the shore makes it highly accessible. Locally,HMS Swift will be relevant when Puerto Deseado's community starts to recognise it as a significant part of their own heritage and local people become involved in the preservation of the wreck.     

Laboratory Research on the Effects of Heavy Equipment Compaction on the in situ Preserved Archaeological Remains

Following the Malta Convention/Valletta Treaty the preferable way for the physical protection of archaeological sites is in situ preservation. When planning in situ preservation, in addition to other issues, it is also necessary to consider changes in physical environment and their impact on in situ preserved remains. This is especially important when human interaction takes place. Recently, an increase in construction on the top of archaeological sites has occurred, thus the effects of heavy equipment compaction need to be studied in more detail.

This paper presents research on the effects of the use of heavy equipment (e.g. rammers and rollers) compaction on archaeological remains. For the purpose of our research, laboratory testing has been performed. In a custom-made steel box, artificial archaeological sites were created using layers of sandy silt and gravel. A variety of archaeological and modern artefacts were placed in these created environments. Some of them were equipped with strain gauges for deformation recording. Through a series of tests a servo-hydraulic piston was used, which simulated the dynamic loading of the artificial sites. Humidity and temperature were recorded before, during, and after each test. Since layers and artefacts were three-dimensionally recorded before and after each test, compaction of layers and movements of artefacts could be studied. With attached strain gauges and visual inspection following each test, deformations and thus damage to artefacts during different stages of loadings was recorded.

The goals of our laboratory tests were the development of a new methodological approach to study the effects of heavy equipment compaction to the archaeological sites, getting an insight into the problems of such tests, and the estimation of the applicability of their results. With the presented results, our research has been a step towards better understanding the effects of heavy equipment compaction on archaeological remains and thus to the preservation of archaeological sites in situ.     

考古发掘与考古发现

考古发现和考古学理论方法是考古学赖以进步的两条腿。考古发现不断刷新考古学家的视野并为考古学研究的深入提供新的资料,考古学理论方法使考古学的眼睛更加明亮,分析和思考更具有科学的力量。理论方法让考古学家对考古发现有更深入的认识,考古发现同时也推动综合研究和理论方法的进步。此外,考古发现往往会引起社会的关注,考古发现和考古学知识的普及可以为考古学的进步提供良好的社会环境,从而对考古学的发展产生强大的推动力量。考古学的持续发展要求考古学家必须正确处理考古发现、考古学自身理论方法的完善以及考古学与化遗产保护、公众知识状况和社会需求的关系。     

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.     

The Odyssey Case: press,public opinion and future policy

The Odyssey Case refers to the dispute between Odyssey Marine Exploration Inc. (OME) and the Kingdom of Spain in the US courts to determine the ownership of more than 500,000 coins, as well as other artefacts, that OME recovered from a wreck‐site it had code‐named Black Swan. However, the process was much more than a dispute over the coins. It reflected many of the components involved in the protection of underwater archaeological heritage, especially when economic and political interests are at stake. Written from the perspective of an archaeologist working for the regional authority responsible for developing archaeological policy, this paper tries to assess the case's impact on future policy development.