Decline in firing technology or poorer fuel resources? High-temperature thermoluminescence (HTTL) archaeothermometry of Neolithic ceramics from Pool,Sanday, Orkney

The Neolithic ceramic assemblage from the multi-period coastal settlement at Pool on the island of Sanday, Orkney is unique because it stratigraphically spans both the earlier round-based (including possible Unstan bowls) and later flat-based (‘Grooved Ware’) traditions. High-temperature thermoluminescence (HTTL) analysis objectively demonstrates that ceramics from the earliest Neolithic layers have been consistently better fired compared to examples from later layers. We suggest two interpretations of these data: either firing technology declined with changing social structures and/or adoption of a different ceramic tradition or that there was greater pressure on fuel resource and management in the later Neolithic. Paleoenvironmental and chronological evidence indicate climatic deterioration in the later Neolithic, which adds further support to an interpretation of a poorer fuel resource at that time. In addition to studies of the HTTL signal, analysis of the ambient temperature modification of the TL signal has potential to support or evaluate dating evidence, and is readily applicable to optically stimulated luminescence (OSL) age data.     

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.     

“芮薪”考辨

西北地区所见的汉代简牍资料中有"芮薪"一词,诸家对这个词的解释都不是十分精当。本文主要利用语言学知识和考古材料,对西北汉简中的一些植物进行考察,对"芮薪"一词的词义和具体所指得出了与诸家不同的观点。我们认为"芮薪"应该是材质比较柔软的草类燃料的统称,西北汉简中的"芦苇"、"慈其"在用作燃料的时候都应该可以称为"芮薪","蒲"和"需蓻"也有可能是"芮薪"所指的燃料。     

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.     

What goes in does not always come out: The impact of the ruminant digestive system of sheep on plant material,and its importance for the interpretation of dung-derived archaeobotanical assemblages

Abstract

On archaeological sites where livestock dung was a major fuel source, plant material that survives digestion intact may well be preserved in the remnants of dung-fuelled fires. Preserved plant remains which were derived from dung relate to the diet of animals, and thus provide a way of investigating the agro-pastoral economies of the past. In order to improve our understanding of the taphonomic processes to which plant material is exposed to during digestion, we applied archaeobotanical methods to the analysis of dung from sheep fed a known diet of cereal and wild plant material. Two clear patterns emerge from these investigations. First, cereal material (grain or chaff) survives digestion poorly and was rarely found in the dung analysed. Second, large proportions of seeds of various wild species survive digestion in an identifiable form, probably due to their small size and/or protective coating. These findings are crucial for reliable interpretation of dung-derived plant material in archaeological settings.     

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 development and operation of Roman hypocausted baths

Hypocausted baths represent physical systems which are susceptible to theoretical and practical examination. A consideration of the development of the hypocaust gives an idea of the state of the art at the time of the Roman occupation of Britain. It also explains why the importance of baths in the history of architecture, usually taken as being almost axiomatic, is determined by comfort physics. A number of problems in the way of a simple theoretical calculation of the fuel consumption is examined, and a calculation of the order of the requirements of a small rural establishment is attempted. The social and ecological implications are briefly touched upon.     

A coalbed methane ‘stratum’ for a low-carbon future: A critical inquiry from the Lorraine Basin (France)

Coalbed methane exploration in Lorraine (France) is part of a rush to unconventional natural gas around the world. These resources are envisioned as a “transitional bridge” to a low-carbon economy dominated by renewable generation. This paper tackles the idea that such a “fuel bridge” could lead to a more sustainable transition. It studies the network of actors and interests involved in exploring a coalbed methane ‘volume’, its modelling and how it becomes public. Through this lens, it shows how a ‘volume’ endures in a ‘stratum’, as well as the political issues related to this reconfiguring of the underground in Lorraine.The article contributes to three debates in relation with political geology. First, it proposes a renewed definition of ‘volume’ based on the work of Michel Serres. The ‘volume’ is not a property of the underground nor a geometric ideality but defined as a transitory ordering of the ‘multitude’ that encompasses material, knowledge and political issues. It enables the development of a more continuous analytical strategy to follow geological and political crossed influences, and contributes to this project by going beyond existing divides (e.g. vitalist/constructivist). Second, the paper provides the reader with a complementary perspective (from the field instead of a compilation of data at an international level) about what it means to assess an unconventional resource. The proposed definition of ‘volume’ does not reduce uncertainty to a matter of knowing but makes it constitutive of the making of a gas potential. This enables one to follow the chain of mediations through which uncertainty is framed and strategically managed to meet industrial, scientific and political interests, while taming local oppositions. Third, the paper analyses why this coalbed methane ‘stratum’ may be democratically contested and transitory instead of preparing the ground for a low-carbon transition. This case study looks at a unique situation in France, namely a private company receiving public support in the context of political tensions about unconventional gas, and shows the country's internal contradictions and delays in updating its institutions and strategy concerning the use of underground resources for a low-carbon transition.