The Use of Animal Bone as Fuel in the Third Millennium BC Walled Enclosure of Castanheiro do Vento (Northern Portugal)

Experiments on fire manipulation of bones as fuel demonstrated that animal bones are effective in the act of maintaining lasting combustion. These experiments are almost always applied to the studies in hunter–gather societies in prehistory, even though the use of bones as fuel is also known in historical times. Based on data and models resulting from these recent experiments, both in laboratory and in real hearths, I tested the hypothesis of the use of animal bone as fuel in the third/second millennium BC walled enclosure of Castanheiro do Vento, in northern Portugal. The faunal assemblage shows some specific characteristics such as a very low percentage of identifiable material and close to 90% of charred bones with a very high index of fragmentation I link the faunal analysis with the results of some experiments recently published. These experiments show the particularities of bone fuel combustion, specifically used in certain activities. Nevertheless, the interpretation of these activities in Castanheiro do Vento is difficult to achieve because of the preliminary state of the investigations. As an additional problem, the available interpretations in the literature concern mostly hunter–gather, and models do not take into account the complex societies of the third/second millennium BC. Copyright © 2015 John Wiley & Sons, Ltd.     

Home Is Where the Hearth Is: Anthracological and Microstratigraphic Analyses of Pleistocene and Holocene Combustion Features,Riwi Cave (Kimberley,Western Australia)

The manipulation of fire is a technological act. The identification of the archaeological signatures of the controlled use of fire has important implications not only for the estimations of the origins and functions of the first fireplaces but also for our understanding of prehistoric technological development and resource use. At Riwi (Kimberley region, Western Australia), excavations over two field seasons have revealed a discontinuous occupation sequence over the past 45 ka, showing numerous, different combustion features interspersed within the deposit. Anthracological and micromorphological investigations at Riwi Cave indicate that the combustion features at the site can be categorised into three types: flat combustion features (type A), dug combustion features (type B) and thick accumulations of mixed combustion residues (type C). These provide evidence for two kinds of combustion practice: (i) fires lit directly on the ground and most likely not re-used and (ii) ground ovens, the latter appearing some 10,000 years after the first evidence for occupation of the site. A comparison of the wood species identified within these combustion features with those from equivalent scattered context levels, enables an exploration of the potential factors influencing wood selection and fire use through time at the site. A detailed understanding of the relationship between wood charcoal remains and archaeological context yields significant information on changes to environmental context and site occupation patterns over time.     

Coal used for Fuel at Two Prehistoric Sites in Southern France: Les Canalettes (Mousterian) and Les Usclades (Mesolithic)

Charcoal analysis—the study of charcoal from archaeological contexts—is designed to reconstruct palaeoenvironment and human use of wood. At two prehistoric sites in the Causse du Larzac (France)—Les Canalettes (Mousterian) and Les Usclades (Mesolithic)—charcoal analysis has revealed specimens whose anatomical structure was abnormally compressed in transverse section. The authors conducted experiments to determine how the compression could have occurred. The result was the first evidence for lignite in Palaeolithic settlements. Lignite fragments in a hearth suggest local Palaeolithic people used it for fuel. The lignite could have come from major coal outcrops within 7 to 15 km of the sites. Coal use is otherwise unknown for Palaeolithic cultures in France, and its use at Les Canalettes during the last glacial is the oldest recorded instance. Coal may have been used for fuel primarily because wood became scarce during the last glacial.     

A new approach to study the fuel used in hearths by hunter-gatherers at the Upper Palaeolithic site of Abri Pataud (Dordogne,France)

The fuel used in hearths in the Upper Palaeolithic period and the management of this fuel have long given rise to questions on intentional or opportunistic human comportment. To understand how fuel was managed during the Aurignacian and Gravettian cultures, hearth samples from the French site of Abri Pataud (ca. 34–20 kyr BP) were collected. An image analysis method for the automated quantification of burnt particles from macroscopic-to-microscopic sediment fractions was developed, and the results obtained using this method were compared with the palaeoenvironmental data available close to the site. At Abri Pataud, the use of bones was dominant during the Pleniglacial, suggesting an intentional practice. However, environmental pressures could have influenced the fuel management practices of the hunter-gatherers, even if the dualistic relationship between the availability of firewood and the use of bone in hearths must be considered. Thus, burnt particle quantification provides more than just an observation of burnt macroremains in hearths: it relates to fundamental information on human behavior.     

Seasoned or green? Radial cracks analysis as a method for identifying the use of green wood as fuel in archaeological charcoal

For several years, sociological questions have been central in anthracology. The development of socio-economic approaches based on the recognition of anatomical signatures in wood has made it possible to focus on topics related to firewood use and its management. The presence of radial cracks (RC) on archaeological charcoal is generally interpreted as the result of the burning of green wood. The present study proposes a verification of this theory by the experimental combustion of seasoned and green wood of Scots Pine (Pinus sylvestris L.). Experimenting with this species was a research priority since it was the dominant taxon (representing 80-100% of the charcoal remains) identified in the Palaeolithic European sites under consideration.The experiments were conducted using two different methods: (i) inside a muffle furnace that allowed us to control the combustions, but in which the combustion process is quite different from most archaeological situations and (ii) in an open fireplace, less controllable but closer to the archaeological conditions. The systematic quantification of the number, length and width of the radial cracks (RC) measured on the transversal sections of the experimental samples demonstrates that (i) radial cracks occur independently of the moisture content of the wood before the combustion (on green and seasoned wood); (ii) however, the average number of radial cracks (RC/cm²) allows distinguishing seasoned from green wood; (iii) in the muffle furnace, the size of the RC appeared to be a good criterion for discriminating seasoned and green wood, but this observation was not confirmed by the open-air combustions. Our results clearly show that the appearance of radial cracks is not diagnostic of the combustion of green wood. Nevertheless, the number of radial cracks (RC/cm²) could represent a new method that might help identifying the combustion of green wood in archaeological charcoal samples.     

Heat,smoke and fuel consumption in a high mountain stállo-hut,northern Sweden – Experimental burning of fresh birch wood during winter

The overall aim of this study was to investigate in situ, the use of an open fire for heating a traditional mountain Sami stállo-hut during winter using fresh mountain birch as fuel. The study took the form of repeated actualistic experimentation and the following parameters were recorded: fuel consumption and logistics, indoor temperature, CO-levels inside the hut and temperature in both the hut and the traditional Sami stone-lined hearth with a stone filling of flat stones. Our results show that fresh birch is an effective fuel and that about 3.6 kg (dry weight) of wood was used per hour; it took a few hours of work per day to obtain the firewood required. The highest temperature recorded beneath the stone filling in the hearth was 437.7 °C. The hearth stored a lot of heat but this did not affect the indoor temperature during the night. The highest indoor temperature indoor was +26.9 °C, but it was generally much lower and varied considerably during the day and in relation to the outdoor temperature. The CO-levels reached 112 ppm at floor level and co-varied with the smokiness experienced inside the hut.     

Stable carbon and oxygen isotopic compositions of wood ash: an experimental study with archaeological implications

Wood ash, composed mainly of the mineral calcite, is an important component in many archaeological sites. Identification of wood ash in the archaeological record is often difficult due to mixing of ash with other calcitic components of geogenic origin and/or due to diagenetic changes. A recent empirical study using the stable isotope compositions of carbon (δ¹³C) and oxygen (δ¹⁸O) in wood ash enabled the identification of mixtures of wood ash with geogenic calcite and to follow diagenetic changes due to partial dissolution and re-precipitation of ash in two prehistoric cave sites in Israel. Little however is known about the processes responsible for the isotopic compositions of wood ash in relation to formation at various temperatures and the influence on isotopic composition of ash from a variety of plant species. Here we present an experimental study of wood ash formed by burning three C3 tree species and one C4 desert bush at different temperatures. The results indicate that there are significant differences in the isotopic compositions of carbon and oxygen between wood ash that forms by combustion at a relatively low temperature (500 °C) and at a higher temperature (900 °C). In addition, we show that the isotopic composition of carbon and oxygen in high temperature wood ash approaches equilibrium over a period of several months and that the carbon isotopic composition of low temperature wood ash may reflect the photosynthetic pathway of the burnt woody species. Lastly, we show that the isotopic compositions obtained from wood ash prepared at different temperatures do not reflect a temperature dependent fractionation process, but a mixing line between calcite that formed by low temperature combustion and calcite formed by high temperature combustion which later underwent re-carbonation with atmospheric CO₂. In addition, we suggest that exchange processes may possibly occur during combustion between decomposing calcium-oxalate and atmospheric O₂, CO₂ and CO. The archaeological implications of this study are discussed in relation to identification of wood ash in the archaeological record, identification of fuel sources and burning temperatures, and diagenetic changes expected in karstic cave environments. The method presented here can be applied at any archaeological site.     

Morphological,chemical and physical changes during charcoalification of wood and its relevance to archaeological contexts

Wood exposed to a heat source can be transformed into charcoal if subject to conditions of carbonisation (in the absence of air) or charring (in restricted air). Charcoal recovered from archaeological sites can yield fundamental information to our understanding of human economic and cultural development over time and (ecological) setting. This work describes the morphological (anatomy, degree of shrinkage), physical (reflectance) and chemical (elemental, molecular composition) properties of charcoal in relation to heat source and wood variables. In this study charcoal and charcoal fuel were experimentally produced whereby temperature (160–1200 °C), time of exposure (2–1440 min), heating rate (high and low) and wood type (angiosperm and conifer) were varied. The results show that charcoal, often described as an inert, black material, has different chemical and physical properties in relation to the investigated variables. By using these different properties it is possible to distinguish between the different types of fires (domestic and industrial) exploited by humans in the past. Morphological analyses and reflectance measurements are effective tools for this purpose and can be used in wood exposed to temperatures of 300 °C and above—temperatures which are relevant to archaeological research. Angiosperm and conifer wood react in different ways when exposed to heat and thus the taxonomic identity of archaeological material needs to be known. Chemical analyses can be used for wood exposed to temperatures below 400 °C whereas elemental analyses of the carbon content can be used for wood exposed to temperatures up to a maximum of 650 °C.     

An ethnoarchaeological study of cooking installations in rural Uzbekistan: development of a new method for identification of fuel sources

Mud constructed cooking installations such as ovens and hearths are common in modern, pre-modern and archaeological domestic contexts in West and Central Asia. Archaeological cooking installations are primarily identified using analogy of shape and size to ethnographic installations. The study presented here establishes direct evidence to the use of fire within mud constructed cooking installations, thus providing means for reducing ambiguity in identification of archaeological cooking installations. In addition, we present here a newly developed method that enables a clear-cut distinction between wood and dung ashes used as fuel materials in many modern and archaeological domestic contexts. The study is based on an ethnoarchaeological research in rural households at the Republic of Uzbekistan that was followed by geoarchaeological analyses of installation walls, wood ash, dung ash and wood and dung standards collected in the study area. Field work included ethnographic observations, interviews with informants and temperature measurements during cooking experiments. We show that changes in the clay mineral structure due to exposure to high temperatures on the interior walls of cooking installations can be detected using FTIR (Fourier Transform Infrared) spectroscopy, providing for the first time direct evidence to the use of fire within such installations. We demonstrate that the temperature recorded by clay alteration on installation walls as well as in the ashes left on installation bottoms does not correspond to baking or cooking temperatures. We also show that the newly developed method, based on the ratio of wood ash pseudomorphs to dung spherulites, separates between wood and dung ashes with very high certainty. Yet, we identify a range of values where differentiation between wood and dung ashes is uncertain, and suggest it results from intensive mixing processes. Lastly, we show that phytolith morphotype analysis is an insufficient tool, if used alone, for distinguishing wood from dung ashes in the study area. The newly developed tools for temperature estimation within mud constructed installations and for fuel origin determination contribute to better understanding of cooking-related practices, and can be applied to archaeological contexts worldwide.     

A Study of the Techniques Used to Make Laohudong Guan Ware in China in the Southern Song Dynasty

Through a combination of analysis and synthesis of Laohudong Guan ware shards from Hangzhou City in southern China, some new hypotheses concerning Guan ware manufacture can be proposed. These suggest that the complex microstructures seen in Guan ware glazes, and which contribute significantly to their jade‐like qualities, may owe much to layers of fine bubbles trapped during the glazing process. It is also proposed that the multi‐layer glazing methods used at the Guan ware kilns at Hangzhou may have helped initially to disguise the relatively coarse and ferruginous clays used for Guan ware manufacture. Once established, the layered glazing technique was used for its own sake—eventually yielding wares that could comprise more glaze than clay. Raw materials and firing temperatures were also explored for this study, and these suggest the use of porcelain‐stone/wood ash mixtures for glaze‐making, with 20–30% calcareous wood ash being the usual amounts. The average heat‐work for the glaze firing seems to have been equivalent to Orton Cone 7, giving a typical finishing temperature of ～1215°C. A single biscuit firing and a single glaze firing seem likely for most Laohudong Guan wares. Studies of the losses that occur in the preparation of calcareous wood ashes suggest that very large quantities of botanic material must have been burned to provide ash for glaze‐making at the Laohudong kiln. From the environmental perspective, a combination of thick glazes and heavy wood‐ash usage would have placed great demands on local fuel supplies.     

The ethnoarchaeology of firewood management in the Fang villages of Equatorial Guinea, central Africa: Implications for the interpretation of wood fuel remains from archaeological sites

In archaeological literature, the study of trees and wood remains is a topic of relatively marginal interest, especially compared to texts on crops and human–animal relations. However, charcoal is the most frequent botanical remain found in archaeological sites. Charcoal analysis can therefore play a major role in the development of studies in both landscape and palaeoethnobotanical reconstruction. The majority of the archaeological charcoal assemblages reflect the exploitation of wood as an energy source (fuel). The archaeological study of firewood selection has been predominantly developed from “eco-utilitarian” or “subsistence economy” perspectives, but has not yet considered fuel collection and use as one of the most enduring categories of human–environment interactions, nor has archaeology looked into its potential as a source of empirical information on past perceptions of, and interactions with, ancient landscapes. The aim of this paper is to expand previous archaeological work on the interpretation of charcoal macro-remains through the study of firewood collection as a historically constituted, socially mediated and archaeologically observable landscape practice. In order to achieve this, we present an ethnoarchaeological case study from the Fang society of Equatorial Guinea (central Africa) aimed at gaining a better understanding of the complex interactions between cultural, ecological and economic variables in firewood collection strategies.     

Fuel, Fire and Heat: an experimental approach to highlight the potential of studying ash and char remains from archaeological contexts

As in traditional societies today ancient societies probably selected different fuels to meet specific heat requirements. Char and ash, the end products of fire, are often found in abundance in archaeological contexts. These end products can provide information regarding (i) the original fuel resource and type, (ii) the characteristics of the fire and (iii) combined with other archaeological evidence shed further light on possible socio-economic activity(-ies) associated with that fire. The three main fuel resources would have been (i) modern vegetation, (ii) fossil fuel and (iii) animal by-products. Local availability and abundance would have influenced the choice made.In this study an experimental approach was adopted to try and distinguish between the three different fuel resources that are known to have been used by ancient societies (and continue to be used by traditional societies today) from their char and ash remains to help determine original fuel-type and understand the relative heating properties. For this end one fuel-type from each fuel resource listed above, namely wood, peat and cow dung, was chosen.     

Archaeobotanical inference of Bronze Age land use and land cover in the eastern Mediterranean

Charcoal and charred seeds at five Bronze Age archaeological sites discern ancient land use in the eastern Mediterranean. Seed frequencies of orchard crops, annual cereals and pulses, and wild or weedy plants are used to characterize plant utilization at different archaeological sites on the island of Cyprus, in the Rift Valley of Jordan, and in the Jabbul Plain and along the upper Euphrates River valley in Syria. Seed to charcoal ratios provide proxies to determine the relative usage of dung versus wood for fuel across the ancient Mediterranean landscape. Greater charcoal and lower charred seed values are interpreted to represent a wooded environment, while higher amounts of charred seeds and minimal wood charcoal suggest a much great use of dung as a fuel source. Interestingly, Politiko-Troullia (Cyprus, Cypriot archaeological sites are, by convention, named for the nearest modern village (Politiko), followed by an italicized toponym (Troullia) referring to the plot of land that incorporates the site) has the lowest seed to charcoal ratio, suggesting its residents primarily burned wood and that the landscape surrounding Troullia remained relatively wooded during the Bronze Age. In contrast, villagers at Tell el-Hayyat (Jordan) utilized a mixture of wood and dung, in contrast to Tell Abu en-Ni’aj (Jordan), and especially Umm el-Marra and Tell es-Sweyhat (Syria), where inhabitants relied solely on dung fuel. Comparative analysis and interpretation of seed and charcoal evidence thus illustrates the variety of fuel use strategies necessitated by the dynamic and diverse Bronze Age landscapes of the Eastern Mediterranean.     

Excavation of an early 17th-century glassmaking site at Glasshouse,Shinrone, Co. Offaly,Ireland

An archaeological research excavation was conducted in the area immediately surrounding an upstanding glassmaking furnace near Shinrone, Co. Offaly, Ireland. It dates to the early to mid 17th century and was built and operated by French Huguenots, probably de Hennezells (de Hennezel/Henzeys/Hensie) who had settled in this region as part of the Crown plantation of King’s County (now Co. Offaly). This furnace, which employed wood rather than coal as a fuel, is a very rare survival, with no other upstanding examples known in Ireland, Britain or the Lorraine region of France where the form probably originated.     

ON THE INTENT TO MAKE CRAMP: AN INTERPRETATION OF VITREOUS SEAWEED CREMATION 'WASTE' FROM PREHISTORIC BURIAL SITES IN ORKNEY, SCOTLAND

Summary.   Vitreous slag-like material, known as 'cramp', from prehistoric cremation burial sites in Orkney is, apart from cremated bone, one of the recurrent remains found within or around Bronze Age burials. Although the suggestion that cramp was formed by the fusing of sand attached to dry seaweed while it was being burnt was first proposed in the 1930s, there has never been a consideration of seaweed's contribution to cremation other than as a potential fuel. Scientific analyses presented in this paper corroborate the use of seaweed. It is suggested that cramp may have been deliberately produced to act as an efficient collector of shattered bone which otherwise could have been lost during the cremation. Far from being a 'waste', cramp could well have been another form of 'human-remains' in its own right.     

Charcoal scarcity in Epigravettian settlements with mammoth bone dwellings: the taphonomic evidence from Mezhyrich (Ukraine)

Fuel management during the Paleolithic periods is an important issue to understand past human subsistence. Numerous Palaeolithic sites relate an abundance of burnt bones in hearths and an absence or scarcity of wood charcoals, which leads studies to focus on burnt bone remains and the use of bones in hearths. Few works take into account the micro-residues of wood charcoals which can still be present in hearth areas and excavated sediments. We studied the Epigravettian site with mammoth bone dwellings of Mezhyrich (Ukraine) previously characterized by its high content of burnt bones and an “absence” of wood charcoal during the so-called mammoth steppe. The presence or absence and proportions of both wood charcoals and burnt bones were quantified in macro-, meso- and microscale sediment size fractions by an image analysis method. Our results show that excavations during field-works at Mezhyrich give only a partial image of the original anthracological record and that most charcoal materials are lost with standard archaeological and anthracological approaches. The scarcity of charcoals in this site was possibly due to an important mass reduction accentuated by the addition of bones in hearths. By applying our protocol we recovered a significant amount of wood charcoals which provides the first ¹⁴C dates from charcoals at Mezhyrich. Numerous charcoals are identified contributing subsequent information about vegetation, environment and burning practices. They indicate, by comparison with pollen data already collected, the presence of forest patches in a mammoth steppe landscape, which might have influenced the collecting behavior of Epigravettian populations.     

Ancient Maya wood selection and forest exploitation: a view from the Paynes Creek salt works,Belize

Ancient building construction wood preserved in a peat bog below the seafloor in a shallow mangrove lagoon in Paynes Creek National Park, Belize, provides an exceptional record of Classic Maya wood use. Identifications of construction wood at Early Classic Chan B'i, and Late Classic Atz'aam Na, are reported and discussed to assess forest exploitation and species selection over time. Black mangrove (Avicennia germinans) dominates the Early Classic assemblage. The Late Classic assemblage is characterized by greater variability and an absence of mangrove species. When considered in the environmental context, identified species conform to principles of optimal foraging. The change in the wood assemblage over time suggests overexploitation of forest resources, resulting in deforestation of the local landscape and subsequent adaptation of foraging behavior. Deforestation is linked to the wider social context in which growing inland populations created demand for salt, putting greater pressure on the forest resources exploited by the Paynes Creek salt works for fuel and timber.     

Accessing Hunter-Gatherer site structures using Fourier transform infrared spectroscopy: applications at a Taltheilei settlement in the Canadian Sub-Arctic

The results of Fourier transform infrared spectroscopy on soils and caribou bone from a Taltheilei culture settlement in northern Canada contribute to developing micro-archaeological approaches suitable for locating and characterizing hearth and midden features on hunter-gatherer sites. A weak yet pervasive signal for montgomeryite was developed from the diagenesis of dispersed ash and caribou processing residues. Disordered calcite, carbonate hydroxylapatite, charcoal, and burned bone in two pit-house hearth deposits indicate that both wood and bone were used for fuel. Crystallinity indices and carbonate/phosphate ratios for bone indicate high intensity burning. These data, in tandem with the presence of semi-subterranean dwellings, demonstrate that this particular tundra-based encampment was occupied during cold seasons, a type of settlement behaviour previously unrecognized in the Taltheilei archaeological record. Our results confirm that Fourier transform infrared spectroscopy is an accessible, rapid, and cost effective means of discovering micro-archaeological evidence valuable for reconstructing hunter-gatherer site structures.     

The aceramic production of <Emphasis Type="Italic">Betula pubescens</Emphasis> (downy birch) bark tar using simple raised structures. A viable Neanderthal technique?

Following on from our previous research into the prehistoric aceramic distillation and production of birch bark tar, this series of exploratory experiments investigated the use of raised structures within a fire. These field-based experiments were conducted using sand, gravel, wood fuel, and bark from Betula pubescens (downy birch). The structures that were created were simple raised sand mounds, which reflected known Neanderthal combustion surfaces from the Middle Palaeolithic. The bulk of the experiments were recorded throughout using a thermocouple to provide temperature readings from the base of the bark pyrolysis chamber. The experiments proved successful at producing birch bark tar and several containers were used to catch the tar for later analysis. Based on the results, the authors contend that not only could Neanderthals control fire but that regular birch bark tar production by Neanderthals was most likely a result of specific chaînes opératoires in order to provide the necessary control and outcomes.     

The Exploitation of Plant Resources by Neanderthals in Amud Cave (Israel): The Evidence from Phytolith Studies

The depositional environments of Amud Cave indicate that phytolith assemblages retrieved from the cave's sediments are an integral part of the Middle Palaeolithic sequence. As such, they provide direct evidence for plant use. The Amud Neanderthals emphasized both wood and grass exploitation. Ligneous parts of trees and shrubs were used mainly for fuel. Herbaceous plants were used for bedding, possibly fuel, and for food. There is clear and repetitive evidence for the exploitation of mature grass panicles, inferred to have been collected for their seeds. These findings suggest that, as with the pattern recently discerned for faunal resources, a broad spectrum of plants has been exploited from at least the end of the Middle Palaeolithic. Phytolith analysis now provides a tool for testing models explaining subsistence and mobility patterns during the Levantine Middle Palaeolithic and for better understanding the role of vegetal resources in shaping these patterns.