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.     

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.     

Relax,Don’t Do It: A Future for Archaeological Monitoring

Preservation in situ and the monitoring of archaeological sites have become important themes since the acceptance and implementation of the Valletta Treaty. In the last few decades, our knowledge of degradation processes has increased manyfold, and a range of techniques have been tested and applied for use in both assessment and monitoring. Despite these successes, all is not well. First, we have little notion of the speed of the decay processes involved. This makes it difficult to distinguish between acute and protracted degradation. Apart from that, many assessments and subsequent monitoring projects rely (too?) heavily on complex and costly specialist technology. For any future preservation — in situ — projects low-tech observations together with best estimates of decay rates and archaeological site information should be combined to make an accurate assessment of the effects of decay on the archaeological record. Monitoring for preservation purposes is only appropriate if (1) decay processes occur within a relevant and measurable time scale, and (2) if mitigating actions can be taken or preservation ex situ can be performed (i.e. a rescue excavation) if significant degradation takes place.     

Founding of a Monumentenwacht for Archaeological Heritage in Flanders (Belgium)

Abstract

In August 2009, Monumentenwacht Vlaanderen set out to develop a new service and monitoring system for archaeological heritage in Flanders. Such an initiative takes time, for it needs to be done thoroughly, and there are many questions that need to be addressed. The answers can be found partly in examples in other countries, but must also be evolved in practice within the Flemish context, where a policy on in situ preservation of archaeological heritage is still in its infancy. This paper explains how this new service has been set up.     

Advisory Commissions for Archaeology — Sense or Nonsense? The Case of Belgium

Abstract

Belgium has a long tradition of consultative commissions, responsible for the preservation of heritage. In the 1940s and 1950s, Belgian archaeologists expressed a need for such an institute, specifically competent for archaeology and the supervision of excavations. Only in 1965, the first members of a National Commission for Excavations were appointed. They had modest powers, but were able to advocate the value of archaeological heritage and, to a limited extent, supervise fieldwork performed by amateurs. The Commission was also asked to prepare a legal text that would protect archaeological heritage. However, ratified laws were not accomplished and, despite much regret of Belgian archaeologists, the Commission was abolished in 1979.

During the 1980s, Belgium underwent several state reforms which ultimately resulted in the complete regionalization of archaeology (1988–89). Throughout this period, a shift in opinion occurred between Walloon (French-speaking) and Flemish (Dutch-speaking) archaeologists. This resulted in different arrangements of governmental agencies responsible for immovable heritage and archaeology. Nonetheless, as UNESCO had recommended in 1968, all three Belgian regions (including the Brussels-Capital Region) installed advisory commissions that were involved in the preservation in situ of archaeological remains. However, these consultative bodies had little influence on politics and policy. Especially in Flanders, the Archaeological Council achieved very little. Probably, the lack of continuity retained the Council from building up a reputation and authority. Nevertheless, advisory commissions for archaeology do make sense in Belgium. They provide a necessary ‘forum’ to discuss problems and to express undivided opinions; they form a ‘channel’ to communicate with policy makers; and they present an ‘instrument’ for advocating the preservation of archaeological heritage.     

‘I Felt Connected to a Past World’: A Survey of Visitors to Colonial Archaeological Sites Conserved In Situ in Australia and New Zealand

Abstract

While there is extensive international literature on the technology and techniques of archaeological conservation and preservation in situ, there has been only limited discussion of the meanings of the places created and the responses they evoke in visitors. Experience in Australia and New Zealand over the past decade suggests that the conservation of colonial archaeological remains is today seen as a far more desirable option, whereas previously many would have suggested that this kind of conservation was only appropriate in ‘old world’ places like Greece and Italy; and that the archaeology of the colonial period was not old enough to be of value. This paper discusses a recent survey of visitors to colonial archaeological sites which reveals some of the ways in which these archaeological remains are experienced, valued, and understood, and gives some clues as to why conservation in situ is an expanding genre of heritage in this region. The visitors surveyed value colonial archaeological sites conserved in situ for the link they provide to place, locality, and memory; for the feeling of connection with the past they evoke; and for the experience they provide of intimacy with material relics from the past. This emphasis on the affective qualities of archaeological remains raises some issues in the post-colonial context, as it tends to reinforce received narratives of identity and history, and relies on the ‘European’ antiquarian appreciation of ruins — making the urban environment more like Europe by creating evidence of similar historical layering.     

Monitoring the burial environment of terrestrial wet archaeological sites in The Netherlands

Abstract

Monitoring the burial environment of archaeological sites is necessary to assess the success of their preservation in situ. Also, monitoring the state of preservation of actual archaeological remains together with that of their burial environment will further our understanding of the degradation processes acting on archaeological remains in situ. These remains consist not only of objects made from wood, metal, stone, etc., but also of pollen, soil features and even micromorphological features. Although, to date, the precise degradation mechanisms of archaeological remains in situ are not yet fully understood, general agreement exists on which parameters should be monitored in wet terrestrial environments. Also, it has been established that in situ measurements are preferable to laboratory analyses of soil (water) samples. In practice, it is difficult to find suitable monitoring equipment for in situ measurement as it must meet many requirements: an in situ measuring principle; stable for a period of at least several months; robust for use in the field; and equipped with a datalogger. A suitable principle exists for measuring the redox potential, however a simple, robust field instrument with datalogger is not yet available. Monitoring of the water table level, temperature and oxygen content is possible with recently developed, commercially available instruments. Monitoring of acidity is less complex as it does not vary as rapidly as, for example, the redox potential; however, the recommended method is still based on analysing soil samples, which is not acceptable in the long term at archaeological sites.     

Long-Term Preservation of Dendroarchaeological Specimens and In Situ Preservation: Problems and Practical Solutions

Abstract

Dendrochronology offers a unique opportunity to address archaeological questions with minimal invasiveness. Often, archaeological tree-ring sampling, and occasionally analysis itself, can be performed while the larger structure or object remains in situ. In comparison to the costs and benefits of excavation (complete or partial) and a growing international call for in situ preservation, dendrochronology provides an effective compromise for the interpretation of wooden material culture.

The current number of archaeological tree-ring specimens worldwide probably exceeds 2,000,000. These specimens have been obtained from thousands of historic buildings, shipwrecks, and other sites and artefacts. These specimens are housed by a variety of public and private entities: museums, universities, governments, private corporations, and individuals. Despite their importance as vouchers for archaeological dates and great potential for future use and new applications, generally little attention has been paid to the long-term curation of tree-ring specimens. This paper identifies some pressing curation problems and suggests that the value and nature of dendroarchaeological research is compatible with international calls for in situ preservation. Some practical suggestions, provided here, could drastically improve the long-term curation of dendroarchaeological specimens, further demonstrating the methodology as a viable and valuable partner to in situ preservation.     

Integrating Archaeological Heritage into Towns and Settlements

ABSTRACT

This article explores factors concerning the urban integration of archaeological heritage in towns and settlements. Archaeological heritage refers to visible, immovable archaeological remains (such as the remains of buildings or structures), sites, and areas (larger complexes). As part of the multidisciplinary process of archaeological heritage management, based on understanding the significance of a site and the goal of enhancing and preserving archaeological heritage in situ, urban integration and its determining factors have not been the subject of systematic research. The present study is derived from the application of deductive research based on theoretical assumptions validated by a qualitative survey. Research has identified 17 factors as the basis for the urban integration of archaeological heritage in towns and settlements. These factors represent a theoretical and practical contribution not only to urban planning but also to archaeological heritage management.     

Managing,Valuing, and Protecting Heritage Resources in the Twenty-First Century: Peatland Archaeology,the Ecosystem Services Framework,and the Kyoto Protocol

Abstract

This paper argues that the development of the Ecosystem Services framework, which has recently emerged as an internationally recognized framework for valuing ‘the ‘natural capital’ of ecosystems, presents a number of opportunities for heritage management and the archaeological record, arguing that the inclusion of archaeological and palaeoenvironmental ‘value’ within this framework presents an opportunity to incorporate heritage alongside a range of other critical ‘services’. It presents a short case study focusing on the problems facing the preservation of peatland archaeological sites and deposits in situ alongside developments within peatland conservation and restoration initiatives partly driven by the ability of healthy, functioning peatlands to sequester carbon and hence mitigate climate change. It is argued that this drive towards peatland re-wetting may bring both positive benefits and opportunities for heritage management but also presents a number of practical issues, which now require active engagement from the archaeological community.     

Impact of Roots and Rhizomes on Wetland Archaeology: A Review

The general premise for successful archaeological in situ preservation in wetlands is that raising the water table will ‘seal the grave’ by preventing oxygen from reaching the deposit. The present review reveals that this may not be the entire picture, as a change in habitat may introduce new plant species that can damage site stratigraphy and artefacts. However, reviews on the types and degree of damage caused by vegetation to archaeological remains preserved in situ in wetlands have hitherto only been sporadically treated in the literature. Thus, this paper provides an overview of the adverse effects that various plants species have on the preservation status of wetland archaeology.Disturbance, due to growth of roots and rhizomes of the surrounding soil is denoted contextual disturbance, whereas deterioration of archaeological remains per se acts by several root-related factors that may be spatially and temporally concomitant. In waterlogged anoxic environments, deterioration is mainly related to (i) preferential growth of roots/rhizomes due to nutrient uptake and lesser soil resistance, (ii) root etching due to organic acid exudates, (iii) microbial growth due to root release of oxygen and labile organic compounds, and/or (iv) precipitation of hydroxides due to root release of oxygen. For example, roots of some wetland plants, such as marsh horsetail (Equisetum palustre), have been documented to penetrate archaeological artefacts down to c. 2 m in waterlogged anoxic soils. Here, we demonstrate that cultural heritage site management may unintentionally introduce deep-rooted or exudate aggressive plants by invoking change in hydrological conditions. Moreover, the implementation of biomass energy utilization and agricultural root depth optimization on a worldwide basis stresses the need for more research within root and rhizome impact on archaeological remains in wetlands. In conclusion, the worst-case scenario may be in situ deterioration instead of preservation, and one essential threat to archaeological wetland sites is the impact of wetland vegetation.     

Bone diagenesis in the European Holocene II: taphonomic and environmental considerations

We have applied cluster analysis to mercury intrusion porosimetry data from 219 archaeological bones (121 human and 98 animal) and soil chemistry data from 219 accompanying soil samples (1 per bone sample), to investigate the influence of soil chemistry on bone preservation. The samples chosen for the study were obtained from sites ranging in time from the pre-modern to the Mesolithic and were representative of burial environments across Europe (from the Baltic to the Mediterranean). These results represent the single largest database for archaeological bone preservation in the European Holocene to date and demonstrate the potential for large-scale diagenetic studies to help develop long term preservation strategies for our European heritage. Despite the variety of sites and environments, bones could be categorised into only four main diagenetic types. Furthermore, soil chemistry appears to significantly affect only one type of preservation, the pathway characterised by loss of mineral. In neutral to basic soils, taphonomy and in particular the differences between the treatment of human and animal remains, becomes the dominating factor in determining preservation. Using these results, strategies for heritage management of archaeological sites can be suggested; grouping sites into those requiring immediate excavation and those where in situ preservation is viable.     

In situ Preservation Solutions for Deposited Iron Age Human Bones in Alken Enge,Denmark

The rich mass deposition of Iron Age human bone material from the Danish site, Alken Enge, is extraordinary not only from an archaeological perspective but also from a preservation point of view. The main find is situated in a waterlogged, anoxic environment which provides excellent preservation conditions and therefore enables in situ preservation of the human bones. However, major differences in local environmental conditions challenge an in situ preservation of the entire site area as parts of the bone material presently deteriorate. In this paper, a multi-proxy environmental monitoring approach is used to document threats and to suggest the best preservation solution for the archaeological finds, whether in or ex situ.     

An Assessment of the Status and Condition of Archaeological Remains Preserved In Situ in the Medieval Town of Trondheim Based on Archeochemical Investigations Conducted During the Period 2007–2010

Abstract

In recent years systematic archeochemical investigations in the medieval town of Trondheim have provided the heritage management authorities with a rich and complex set of data concerning the status and condition of the cultural deposits in the anthropogenic material. The collected data raises important questions for the long-time management of in situ preservation for archaeological material in non-saturated zones. In this paper we present the standardized scientific methods used in these archeochemical investiga- tions. We examine the results from several sites in the town and discuss the challenges facing modern heritage management in its efforts to protect a complex body of archaeological material in the non-saturated zone. We show that sediments with a thickness of 1–2 m have low levels of moisture and organic matter, and most of the inorganic parameters analysed are found in oxidized form with low preservations. The 2–3 m thick anthropogenic sediments showed better preservation conditions.     

Visible Archaeological Remains in Towns and Parks

This paper relates a specific and professional understanding of the nature of archaeological sites to management needs and approaches. It focuses on how the nature of the resource itself relates to a system of valuation, conservation and preservation. The perspective taken is that of the contribution of landscape planning to the development of tourism and heritage management. One of the central aims is to explain the visual values of archaeological remains in the landscape, relating them to the different measures of preservation available for archaeological sites. Examples are included from Latvia and other European countries.     

In Situ Preservation of Ancient Floor Mosaics in Turkey

Abstract

As stated in the Burra Charter (1979) ‘A building or work should remain in its historical location. The moving of all or part of a building or work is unacceptable unless it is the sole means of ensuring its survival’. This statement has been neglected many times during rescue excavations in Turkey (e.g. Zeugma), whereas the destruction of ancient floor mosaics caused by lifting, especially when carried out by incompetent or inexperienced personnel at systematic archaeological excavations, has steered the authorities desire to preserve them in situ. However, due to the lack of conservation professionals and insufficient resources for conservation, it becomes a difficult issue to provide an effective preservation scheme for archaeological excavations. This paper aims to discuss this important issue in terms of the national legislation, preventative and interventive conservation approaches at various sites, exhibition and maintenance of mosaics, as well as the training of conservation technicians in Turkey.     

Monitoring the Environmental Risks Around Medinet Habu and Ramesseum Temple at West Luxor,Egypt, Using Remote Sensing and GIS Techniques

Today, the preservation of cultural heritage is a pressing issue especially for territories subjected to a long period of human action that could adversely influence environment and heritage properties, thus producing a deterioration of archaeological features and alteration of historical landscape. In this paper, the environmental risks and their effects on preservation issues are investigated for the archaeological area of the Luxor city (south of Egypt) where the most famous Temples in Egypt are located. A comprehensive analysis has been conducted for the Ramesseum and Medinet Habu temples considering their building material and characteristics, environmental (geological and hydrological) setting, and past and ongoing changes around the monument areas. Satellite multitemporal images have been used to detect all the changes mainly linked to the expansion of urban and agriculture areas. Results from the analysis conducted along with in situ investigations have suggested that many of the environmental problems around the archaeological areas are coming as a result of urban and agriculture sprawling. Both of them strongly influence the distribution in the levels of groundwater which along with temperature are considered as the main causes of the deterioration process affecting the Medinet Habu and Ramesseum temple. The degree of weathering damage appears to be much more dependent on exposure characteristics of the investigation areas, especially as related to salt weathering processes. Innovative solutions to support the preservation of these temples are herein presented and discussed.     

Take the Right Decision Everybody

Abstract

The archaeological deposits in medieval towns are among the most important and distinctive heritage monuments in Norway. At the same time they are among the more challenging phenomena confronting heritage management authorities, municipal planners, and property owners/developers alike, especially in relation to building and infrastructure projects. The modern settlement has developed on top of medieval and younger deposits which means that not only are they an irreplaceable depository of historical information, but they also form a significant part of the modern town’s physical foundation.

Since 2002 the Directorate for Cultural Heritage in Norway (Riksantikvaren) has been funding systematic monitoring of archaeological deposits of the World Heritage Site Bryggen in Bergen. The monitoring programme consists of several approaches: archaeological assessment of the deposits state of preservation, biochemical investigation of preservation conditions within the deposits, hydrogeological mapping of the water table, water flow, and other given parameters.

Continuous systematic monitoring by using testable, replicable methods and measures, data, and results acquire increased quality and validity. These in turn provide the cultural heritage management with a toolbox for making correct decisions and thereby allow the government’s preservation targets to be attained. But, most important, it guarantees the preservation of the ‘underground archives’ and at the same time allows the urban centres to develop.

This paper presents the knowledge developed through monitoring the Bryggen site as a basis for an official Norwegian standard covering archaeological, biochemical, and hydrogeological deposit investigations.     

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.     

Nydam Mose: In Situ Preservation at Work

Abstract

The site of Nydam Mose saw the beginning of systematic research into in situ preservation of waterlogged archaeological sites on land at the National Museum of Denmark. In the past fifteen years a generic approach to in situ preservation of archaeological sites has been developed based on this research. This article is primarily a review of this generic approach, summarizing the methods and results with particular reference to the published results from the investigations in Nydam Mose.