The Use and Deployment of Modern Wood Samples as a Proxy Indicator for Biogeochemical Processes on Archaeological Sites Preserved in situ in a Variety of Environments of Differing Saturation Level

Abstract

In situ preservation of archaeological sites is becoming an ever increasing trend as a means of preserving our cultural heritage. In connection with this the environmental conditions, such as water level, dissolved oxygen, temperature, pH and water chemistry, of a site are often monitored. It is generally agreed that a waterlogged and anoxic environment is essential for optimal preservation conditions but the set-up and maintenance of an environmental monitoring programme can be costly.

This paper discusses the design and use of a system whereby modern samples of wood can, with a minimal disturbance of the soil, easily be deployed and retrieved from archaeological sites. The system was deployed in an unsaturated environment, an environment with fluctuating water levels and a fully saturated peat bog. The samples were assessed after two years using microscopic, physical and molecular biological methods, and the types of wood-degrading organisms seen were compared with the results of environmental measurements. Modern wood samples were used, as the microbial ecology of wood-degrading organisms in these different types of environments is relatively well documented. Preliminary conclusions show that the deterioration processes of modern wood samples in these environments act as a good proxy indicator of the environmental conditions and biogeochemical processes ongoing at a site.     

A multi-proxy palaeoenvironmental investigation of the findspot of an Iron Age bog body from Oldcroghan,Co. Offaly,Ireland

In 2003, the remains of an Early Iron Age bog body, known as ‘Oldcroghan Man’, were recovered during the cutting of a drainage ditch in a bog in the Irish Midlands. Only some fingernails and a withe fragment remained undisturbed in situ in the drain face, providing the sole evidence for the original position of the body. A detailed reconstruction of the depositional context of the body has been undertaken through multi-proxy analyses of a peat monolith collected at the findspot. The palynological record shows that the surrounding area was the focus of intensive human activity during the Later Bronze Age, but was largely abandoned during the Bronze Age–Iron transition in the mid-first millennium BC. In the mid-4th century BC, a bog pool developed at the site, evidenced in the stratigraphic, plant macrofossil, testate amoebae and coleopteran records. Plant macrofossil and pollen analysis of peat samples associated with the fingernails suggests that the body was deposited in this pool most likely during the 3rd century BC. The absence of carrion beetle fauna points to complete submergence of the body within the pool. Deposition occurred shortly before or around the time that the surrounding area again became the focus of woodland clearance, as seen in the extended pollen record from the peat monolith. This period corresponds to the Early Iron Age in Ireland, during which renewed cultural connections with Britain and continental Europe can be seen in the archaeological record and widespread forest clearance is recorded in pollen records from across Ireland. The palaeoenvironmental results indicate, therefore, that the demise of Oldcroghan Man took place at a pivotal time of socio-economic and perhaps political change.     

Pollen Extraction for Arid-land Sediments

Abstract

Critical examination of traditional extraction procedures employed to recover pollen from a variety of archeological contexts demonstrated the inadequacy of many such techniques. Particularly in arid zones, where pollen preservation is notoriously poor, inappropriate laboratory analysis acts to distort grains further. A satisfactory methodology for pollen samples recovered from areas subjected to such deteriorating effects as oxidation and weathering is essential for archeologists attempting to reconstruct prehistoric environments. A new extraction methodology harmless to pollen grains, yielding excellent pollen counts and preservation from archeological soils was, therefore, experimentally developed for arid-land sediments.     

Pollen analysis in the context of clearance cairns from boreal forests – a reflection of past cultivation and pastoral farming

The former agricultural use of two sites located in the boreal forest of eastern Norway is investigated through pollen analysis. A peat profile was taken from the vicinity in each of two clearance cairn fields where several cairns were analysed for pollen. The pollen samples from the peat profiles give an environmental context for the pollen samples from the clearance cairns, and this combination of samples assists in evaluating the management practices that were in place on the cairn fields during different time periods. In both study areas cultivation layers under the clearance cairns are dated to the Late Roman Iron Age (cal. AD 200–400), while the oldest clearance cairns are dated to the Migration period (cal. AD 400–570), and a second phase of clearance cairn establishment is dated to the Medieval period (cal. AD 1030–1537). Abandonment of the two cairn fields is dated to c. AD 1700. Pioneer trees were a feature on or around the clearance cairn fields during most of the Iron Age, whereas the cairn fields were more open in medieval times. The investigation suggests that cereal cultivation on the clearance cairn fields is difficult to detect in local peat deposits, and that caution is needed when interpreting lack of Cerealia pollen. Management practices on the cairn fields are discussed and a change in management practice is indicated in association with medieval intensification.     

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.     

Physical and Geochemical Characteristics of Soils from Angel Mounds State Historic Site,Indiana, including a Case Study of Sherds from Unit A

Abstract

Using physical and chemical characteristics of soil to evaluate archaeological artifacts and their preservation potential along with associated features is well established. The soil characteristics and geochemistry of the Angel Mounds site (12Vg1) indicate the soil geochemistry is very homogenous and composed of loams and silt loams with a range of pH values from 4.69 to 6.17, mean value of 5.40 ± 0.47. The slightly acidic nature of the soil favors the preservation of pollen and soil diatoms, with minor corrosion potential for the bone, shell, and sherd artifacts. A comparison of the geochemistry of the soils from Unit A and site-wide sampling to sherds from Unit A suggests that elevated phosphorus (P) in the sherds is either the result of the addition of a P-rich temper material or from the sourcing of nonlocal clay-rich sediment, and not from use-derived residue or from the soils themselves.     

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.     

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.     

The water chestnut (Trapa natans L.) as a food resource during the 4th to 1st millennia BC at Lake Federsee,Bad Buchau (southern Germany)

Abstract

During archaeological excavations at several wetland sites around Lake Federsee, remains of water chestnut were detected. The finds are dated to between the 4th and 1st millennia BC. Until recently the starch-containing nuts of water chestnut were used for human nutrition in Europe. The nuts can easily be harvested in autumn. Pollen and plant macrofossil remains from several sites are proof of a wide distribution during the Holocene, probably influenced by humans. Nowadays this annual water plant is extinct in many parts of Europe. The growing conditions of water chestnut are strongly restricted with regard to water quality, depth and temperature, and therefore finds of this plant have the potential to allow reconstruction of former ecological conditions.     

Chenopodium Seeds in Open-Air Archaeological Sites – How to Not Throw the Baby Out with the Bathwater

ABSTRACT

Differentiating between charred and uncharred plant remains may appear straightforward but for some taxa (here fat-hen, Chenopodium album type) can be very problematic. Recognition of the preservation state is obviously crucial for archaeobotanical data derived from dry, open-air sites. Fat-hen as a common weed, is also one of the most important components of a persistent soil seed bank. It is also a well-known food plant, gathered or cultivated. Numerous findings of fat-hen seeds in unclear states of preservation were noted in the Early Neolithic sites of the Linear Pottery culture in Kuyavia (N Europe). In previous studies such specimens were omitted as probably uncharred. Re-examination of Neolithic finds of fat-hen from that region showed the link of their abundancy with the earliest phases of the Neolithic occupation. The plant probably played an important role in the diet of the early Neolithic settlers there. It may indicate intensive use of local, open, fertile, probably alluvial areas. Distinguishing between ancient and modern specimens of that common weedy plant, producing large amounts of small, black, resistant seeds is thus very important, holding a great potential to shed new light on the origins of agricultural societies in this part of northern Europe.     

A Ticking Clock? Preservation and Management of Greenland’s Archaeological Heritage in the Twenty-First Century

ABSTRACT

Evaluating the rate of deterioration at archaeological sites in the Arctic presents several challenges. In West Greenland, for example, increasing soil temperatures, perennial thaws, coastal erosion, storm surges, changing microbial communities, and pioneer plant species are observed as increasingly detrimental to the survival of organic archaeological deposits found scattered along the country’s littoral zones and extensive inner fjord systems. This article discusses recent efforts by the REMAINS of Greenland project for developing a standardised protocol that defines the archaeological state of preservation, the preservation conditions, and asset value of organic deposits. Special emphasis is given to the degradation of materials such as bone and wood that are historically observed to be well-preserved in Greenland but now currently at risk. The protocol provides a baseline for monitoring future changes and will assist archaeologists in Greenland with a procedure for documenting and predicting areas of increasing vulnerability due to a warming climate.     

Ethno-geochemical and Phytolith Studies of Activity Related Patterns: A Case Study from Al Ma’tan,Jordan

ABSTRACT

Understanding Neolithic sites in southwest Asia is often difficult because of the lack of preservation of organic remains and the effects of various taphonomic processes that alter the original record. Here, we use an ethnographic approach to test the potential of using plant phytoliths and geochemistry to aid our interpretation of southwest Asian Neolithic sites. Our study of a recently abandoned stone and mud constructed village in Jordan, shows that for certain activity types, phytoliths and geochemistry can help distinguish different construction methods and functions, particularly for burnt areas, animal use areas and where there has been the addition of a specific construction material. For features constructed from the same source materials distinctions are more problematic. Geochemical and phytolith proxies were individually effective in distinguishing activity areas and construction materials, but signals were diminished when the statistical analysis was run on both forms of evidence combined. It is therefore recommended that the data from plant phytolith and geochemical analyses are subject to separate statistical tests and that the two sets of results are used in combination to interpret archaeological sites and their uses.     

馆藏金属器物上浅蓝色铜锈蚀物的辨别与成因分析

不同于新出土青铜器上的锈蚀物,博物馆藏金属器物上经常可见浅蓝色铜的锈蚀物。为辨别和探析其成因,通过采用扫描电子显微镜-能谱仪(SEM-EDX)、X射线衍射仪(XRD)和激光拉曼光谱仪(Raman)进行元素成分和物相综合分析,发现其为铜的有机盐。这些有机盐包括简单(或碱式)的甲酸铜和乙酸铜,也包括复杂的含有钠离子和碳酸根的乙酸铜NaCu(CO₃)(CH₃CO₂)、含有钠离子和氧离子的水合甲酸铜Cu₄Na₄O(HCOO)₈(OH)₂·4H₂O。这种浅蓝色铜的有机盐形成根源主要有两种:储存或展览环境的不当;用于除锈的化学试剂的残留。要杜绝这类锈蚀物的形成需要确保储存和展览器物的环境低湿度且无有机酸释放材料的存在。对经过化学处理的器物应确保将化学试剂清理干净且无任何残留以绝后患。对复合材料器物的处理更应谨慎,因为对不同材质的处理和保存环境要求不一样,要个例对待。     

Interdisciplinary approach for reconstructing an alder-based historical agricultural practice of the Eastern Ligurian Apennines (NW Italy)

Data from four soil profiles studied through pollen and macroscopic charcoal analyses were used to identify specific palynological assemblages associated with a traditional land-use system documented in the Eastern Ligurian Apennines (NW Italy) between the 18th and early 20th century, concerning a cyclical use of grey alder plots for temporary cultivations involving to the use of controlled fire. This is the first attempt to verify on palynological evidence some hypotheses raised by previous historical ecology studies about the consequences of this agricultural practice (recently named alnocoltura) on past and present vegetation. Our investigations underline (1) high percentages of anthropogenic pollen indicators, (2) increase of Ericaceae percentages, (3) low pollen percentages of Alnus, (4) high macrocharcoal concentrations and (5) high values of palynological richness during periods affected by the alnocoltura cycle according to the historical sources. Similar patterns are also detectable in pollen diagrams from two adjacent peat bogs. The paper shows the strength of an interdisciplinary methodology (field observations, cartographical and archival historical data, palynological and archaeological investigations) for studies of past land-use systems. By demonstrating the necessity of a long-term prospective in environmental reconstructions for the preservation of the cultural landscape, one of the important elements of this research is its potential contribution to issues of habitat management and nature-conservation policy. Further analyses are needed to test the replicability and reliability of the hypotheses derived from this study.     

Combining pollen and charcoal: evaluating Holocene vegetation composition and dynamics

Pollen analysis reveals vegetation change on a local and regional level over (ideally) continuous time spans but with complications when it comes to the reconstruction of spatially precise species occurrence and composition. Wood charcoal analysis provides site-related information on species occurrence and woodland composition, especially when sediments containing pollen are lacking, but is normally discontinuously available and has the danger of human bias due to potential selection of certain species for e.g. fire making, house construction or charcoal making. Combining the two methods – assuming that suitable palaeoarchives are neighbouring – might compensate for their disadvantages and strengthen the interpretations on vegetation composition and dynamics on a local, extra-local and regional scale. Three examples are given where pollen analysis from “classical” archives – mires and lake sediments – was carried out, and where additionally species identification of wood charcoals was done on samples extracted from close-by archives. The first example (Kugelstattmoos, Bavarian Forest, Germany) combines a Holocene pollen diagram derived from a small mire with late medieval/early modern times charcoal spectra from charcoal production sites which are situated on the margin of the mire. Results show the local occurrence of the main woodland species Fagus sylvatica and Abies alba, and raises new questions on the montane species composition of the formerly natural forests in the Bavarian Forest. The second example (Bargstedter Moor, Schleswig-Holstein, Germany) combines Holocene pollen diagrams from a peat bog with late medieval/early modern times charcoal spectra from charcoal production sites in a woodland close to the bog. It shows the role of Quercus, Fagus, Alnus and Carpinus in medieval and early modern times woodlands and its use by man. The third example (Kleiner Tornowsee, Brandenburg, Germany) combines pollen data from sediments of a small lake with charcoal data derived from Holocene colluvisols and soils. The examples show that anthracological and palynological data complement one another to create a more detailed picture of woodland history and landscape change than one method alone would provide.     

A Predictive Map of Compression- Sensitivity of the Dutch Archaeological Soil Archive

Abstract

Weak soils like unconsolidated clay and peat may deform and compress considerably by loading, for example, by sand bodies for roads and railways. Archaeological sites within such easily compressible soil layers may therefore be heavily affected by different kinds of construction works. The vulnerability of archaeological sites to compression is largely dependent on soil properties like lithology, grain-size, and previous loading history. This may therefore differ considerably. Predicting the compression sensitivity is of great value for planners, since they can estimate in which areas in situ protection of archaeological sites may be feasible and where it would require (costly) technical measures or plan adaptations.

As part of the Cultural Heritage Agency’s research programme on construction and archaeology, we prepared predictive maps of the compression sensitivity of the subsurface sediments in the Netherlands for 1 m depth intervals from 0 to 20 m depth.

The maps were constructed using a full 3-D model of the subsurface of the Netherlands.

In combination with the Indicative Map of Archaeological Values (IKAW) that is already available, these maps can be used to better estimate the technical measures needed and costs involved for in situ protection of archaeological sites in the planning phase of construction projects.     

Eco-Archaeometry: Interdisciplinary Applications in Egypt

Abstract

One of the problems currently faced by modern society is the worldwide catastrophic deterioration of archaeological and cultural sites directly exposed to the action of the environment. Frequently, it has proved difficult to identify the processes responsible for these deteriorations, which are often the result of an abrupt change in site specific environmental conditions. To understand them a broad interdisciplinary approach is needed, and consequently, a substantial input from several disciplines, such as archaeology and archaeometric, environmental and conservation sciences, is necessary. Such interaction is particularly necessary on a basic research level, and can best be achieved if the relevant disciplines are drawn together a priori on equal footing into a complementary effort in eco-archaeometry. The primary goal of eco-archaeometry is to identify and quantify physicochemical processes which cause the deterioration of ancient cultural patrimony. Its findings are essential prerequisites for the development of optimum, safe methods for conservation and preservation of ancient monuments. Some examples of the eco-archaeometric approach in Egypt are summarised and it is demonstrated that without an interdisciplinary approach such studies would not have been successful.     

Pollen analysis of coprolites from a late Pleistocene–Holocene cave deposit (Wezmeh Cave,west Iran): insights into the late Pleistocene and late Holocene vegetation and flora of the central Zagros Mountains

Coprolite pollen analysis is increasingly used by palynologists to reconstruct the palaeovegetation especially in the arid to semi-arid regions where lakes and peat bogs are scarce. This study is the first palynological analysis of coprolites in Iran to examine their potential in palaeoenvironmental reconstructions. Four pollen-rich coprolite samples were studied from the Wezmeh Cave in western Iran with a recently discovered late Quaternary (70 ka to sub-recent) faunal assemblage dominated by carnivore remains. Pollen analysis of coprolites shows that a mountain steppe dominated the glacial landscapes of the area. Only one sub-recent sample indicates the presence of dispersed tree stands. One sample was rich in Tulipa pollen suggesting that tulips were relatively abundant during the glacial periods. Cousinia (Asteraceae) pollen was found in all samples with considerable values in one sample indicating its importance in the glacial landscapes of the Zagros Mountains. This study revealed that coprolite pollen analysis can provide an invaluable source of information to understand the floristic composition of palaeolandscapes of the Irano-Turanian region.     

On the challenges and benefits of indoor archaeology: 15 years at the Archeodome (Mitchell Prehistoric Indian Village,South Dakota)

Abstract

Field archaeology is normally associated with outdoor excavation and exposure to the natural environment. Archaeological excavations have adapted to a wide spectrum of these conditions, but the recent prominence of archaeological sites as tourist attractions and educational facilities has occasionally led to dramatically different environments for the archaeological recovery, interpretation, and preservation of evidence, including facilities that permit indoor excavation. This article explores 15 years of experience at the Mitchell Prehistoric Indian Village in South Dakota. An “Archeodome” covering part of the site represents a non-traditional excavation and preservation environment that presents considerable benefits and challenges for archaeologists. The structure provides the basis for evaluating the nature of indoor excavation within its archaeological and educational context and provides a cautionary note for archaeologists, heritage groups, tourist boards, and others interested in the preservation of archaeological sites. Though this article focuses on the Mitchell site, the information reported has broad implications for sites where structures cover archaeological deposits.     

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.