EVALUATION OF THE APPLICABILITY OF CONVENTIONAL METHODS FOR THE CHEMICAL CHARACTERIZATION OF WATERLOGGED ARCHAEOLOGICAL WOOD

A series of 112 waterlogged archaeological wood samples of different provenances, wood species, burial times and states of preservation were analysed with the aim of assessing the validity (in terms of limits and reliability) of procedures conventionally used in the pulp and paper industry, to evaluate the state of preservation of decayed wood. In particular, the extent of any damage wrought on decayed wood tissue by the repetitive cycles that characterize these procedures was evaluated as a function of the degradation of the samples. The results indicated that standard methodologies give reliable measurements regardless of the extent of wood decay. However, it is essential to compare these data with those of non‐decayed wood that has been measured using the same procedures to take account of the errors that are inherent in these methodologies and that affect measurements.     

Editorial: Palaeolithic America

Abstract

We present the results of the Cerro Jazmín Archaeological Project, a mapping and intensive survey project of a hilltop urban center in the Mixteca Alta, Oaxaca, Mexico. Our archaeological and geomorphological investigations reveal a long history of intermittent occupation with the time of maximum occupation, the Early Postclassic, corresponding with soil formation and landscape stability. Our population estimates are compared with agricultural production projections to assess the city's capability to feed its population and we argue that it functioned as an agricultural center. In a broader discussion of landscape and urbanism, Cerro Jazmín's managed labor was needed to build, manage, and maintain its terrace systems. Our findings show that large urban populations do not necessarily cause environmental degradation.     

ORGANIC RESOURCES AT THE IRON AGE DÜRRNBERG SALT‐MINE (HALLEIN,AUSTRIA)—LONG‐DISTANCE TRADE OR LOCAL SOURCES?*

Remarkable preservation circumstances for organic material at the Iron Age salt‐mine on the Dürrnberg Mountain offered the opportunity to analyse a large amount of wood and human faeces. One aim of the studies was to discover the origin of the important resources food and wood. Concerning the question of ‘the linking role of the Alps in past cultures’, the archaeobotanical record proves intracultural but no intercultural connections at this place in Celtic times. The preliminary results show that the Dürrnberg population used differentiated strategies to manage a continuous food and wood supply. While the wood supply was based on the management of local sources, the food supply had to be linked into a regional and long‐distance trade system.     

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.     

Potassium–Calcium Glass: New Data and Experiments*

The chemical composition of potassium–calcium ‘wood‐ash’ glass reflects the elemental pattern of the involved non‐volatile base materials in quartz sand, wood ash and possibly potash. The essential elemental ratio K₂O/CaO of wood ash varies between 0.2 and 0.8, and depends on the habitat and geological substratum of the wood rather than on the tree species; ratios between 1.0 and 3.0 in wood‐ash glass are only possible when potash is added as a third base material. Melting temperatures of wood‐ash glass sensu stricto, termed K–Ca‐2, produced with the two raw materials quartz sand and wood ash, are between 1250°C and 1400°C, while those of three‐component‐glasses, termed K–Ca‐3, are between 900°C and 1250°C, according to the amount of added potash. Experimentally produced glass displays different hues, from colourless to brown, olive‐green and pink, according to the chemical composition of the wood ash. Elevated MnO concentrations between 0.5 and 3 wt% may originate from wood ash and are hence not necessarily an indicator of colour‐inhibiting additives. Phosphate stemming from wood ash is an essential discriminator between wood‐ash glass and potash–lime glass. Because wood ash contains only minor amounts of sodium, wood‐ash glass with equal concentrations of potassium and sodium is a hybrid glass type, where besides quartz sand, wood ash, possibly potash and also soda‐rich cullet have been applied for glass production.     

DETERIORATION ASSESSMENT OF WATERLOGGED ARCHAEOLOGICAL LIGNOCELLULOSIC MATERIAL VIA 13C CP/MAS NMR*

This study investigates the residual chemical composition of waterlogged archaeological lignocellulosic material found in Greece. Hazelnut pericarps and oak wood found in a 16th‐century wreck, along with endocarps of olives dated at 300 bc , were examined. ¹³C CP/MAS NMR was applied to compare fresh and waterlogged archaeological materials. Results show qualitative alterations in their composition. The virtual absence of peaks at ~21 ppm and ~173 ppm, corresponding to hemicelluloses in all archaeological materials, indicates that these constituents can be an important indicator in assessing the type and degree of deterioration.     

CHANGES IN THE METAL CONTENT OF HUMAN HAIR DURING DIAGENESIS FROM 500 YEARS,EXPOSURE TO GLACIAL AND AQUEOUS ENVIRONMENTS

Scanning electron microscopy, inductively coupled plasma mass spectroscopy and time‐of‐flight secondary ion mass spectrometry have been used to examine the extent and possible mechanisms by which the metal content of human hair is altered by exposure to aqueous environments. The results, using both modern hair and samples from 500‐year‐old hair associated with glacier‐entombed remains, show that the metal content has been altered sufficiently so that the interpretation of the metal signature in terms of diet or disease is problematic. While endogenous information is difficult to glean from these data, interesting observations have been made of possible early stages of mineral authigenic deposition. The chemistry of the outer hair surface was found to be consistent with deposition of Fe and Al silicates, as well as other mineral phases. The ancient hair was analysed at the root region and included a comparison of the internal versus external composition to assist in identifying the diagenetic processes.     

THE MELTING FURNACE OF THE DERRIÈRE SAIROCHE GLASSWORKS (COURT,SWISS JURA): HEAT‐INDUCED MINERALOGICAL TRANSFORMATIONS AND THEIR TECHNOLOGICAL SIGNIFICANCE*

Seventy‐one oriented specimens from the pre‐industrial reverberatory melting furnace of the Derrière Sairoche glassworks (Swiss Jura) were analysed. During its period of activity (1699–1714), this glassworks produced wood‐ash glass of liquidus temperatures up to 1400°C. Textural and mineralogical features point to temperatures around 1500°C in the melting chamber. The inner structure of the furnace shows chemical contamination due to ash, molten glass and furnace gases. These results reveal the pyrotechnological know‐how of the glassmakers and prove that the thermal performance of this kind of furnace has been under‐evaluated in the past.     

THE CHARACTERIZATION OF WATERLOGGED ARCHAEOLOGICAL WOOD: THE THREE ROMAN SHIPS FOUND IN NAPLES (ITALY)*

Three apparently well‐preserved shipwrecks dating back to Roman times were brought to light near Piazza Municipio in Naples (Italy), during the excavation for the construction of Line 1 of the subway. The shipwrecks were covered by marine sand and silt, below the water table. In order to establish the nature and the extent of wood degradation and, therefore, determine how best to preserve the shipwrecks, a diagnostic investigation was carried out. The study involved the identification of wood species, chemical characterization of the residue component and physical and micro‐morphological characterization.