Effective hydration temperature of obsidian: a diffusion theory analysis of time-dependent hydration rates

An estimate of effective hydration temperature (EHT) is needed for chronological use of obsidian hydration data. This paper describes a method for calculating EHT by the practicing archaeologist, replacing three techniques that are in general use today: estimates based on mean temperature, numerical integration of models of diurnal and annual temperature variations, and use of temperature cells. The hydration (or diffusion) coefficient of obsidian is a function of temperature and thus is time varying, while the classic quadratic law of hydration is not valid for time-varying diffusion coefficients. This paper presents a mathematical solution to the case of a time-varying hydration coefficient, based on diffusion theory, with a concise definition of EHT. It is shown that the results are not affected by concentration dependence in the diffusion coefficient. A computer program to compute the rigorous solution is described, and data are presented to explore the resulting range of variation. That use of the Lee equation to compute EHT is not appropriate for obsidian hydration studies is evident from the data presented. The effects of paleoclimatic variation are estimated, and an algebraic best fit equation and worksheet are provided as practical aids to the archaeologist.     

A contribution to the study of post-depositional alterations of pottery using TL dating analysis

In luminescence dating, the potassium concentration significantly contributes to the dose rate value in the age estimation. Within this study, fine-grain thermoluminescence dating has been applied on sherds of calcareous pottery of known age, excavated at a Roman site in Mallorca, Spain. For those of the samples that showed signs of severe potassium leaching, according to chemical and mineralogical examination, the thermoluminescence analysis provided overestimated dates. By using the known archaeological age of the samples, a corrected dose rate value can be estimated which provides the potassium concentration averaged for the burial period. Finally, a step-like model can then be used to estimate the fraction of the burial period after which most of the alteration effects took place.     

Book reviews

The Solitary Self: Jean‐Jacques Rousseau in Exil and Adversity. By Maurice Cranston (Chicago, IL: University of Chicago Press, 1997) xii + 247 pp. $29.95 cloth.

The Self‐Aware Image: An Insight into Early Modern Meta‐Painting. By Victor I. Stoichita (Cambridge: Cambridge University Press, 1997) xv + 345 pp. $85.00, £55.00 cloth.

The Cambridge Companion to Nietzsche. Edited by Bernd Magnus and Kathleen M. Higgins (Cambridge: Cambridge University Press, 1996) ix + 403 pp. $18.95, £13.95 paper, $59.95, £40.00 cloth.

David Hume: Political Essays. Edited by Knud Haakonssen, Cambridge Texts in the History of Political Thought (Cambridge: Cambridge University Press, 1994) lxvi + 346 pp. $49.95, £30.00 cloth, $15.95, £10.95 paper.

Sartre, Foucault, and Historical Reason. By Thomas R. Flynn (Chicago and London: The University of Chicago Press, 1997) 340 + xvi pages. $18.95 paper.

Shaping World History: Breakthroughs in Ecology, Technology, Science, and Politics. By Mary Kilbourne Matossian (Armonk, NY: M.E. Sharpe, 1997) 264 pp. $62.95 cloth, $22.95 paper.     

Stylistic Change as a Self-Organized Critical Phenomenon: An Archaeological Study in Complexity

Archaeologists can learn from models of evolution as a self-organized critical phenomenon. Self-organized critical systems are large, interactive systems that organize into a critical state where minor events can trigger chain reactions. Such systems demonstrate power-law distributions in the size of changes, or avalanches, that occur. The theory of self-organized criticality is important in that it implies that the evolution of complex systems may be driven more by interactions between agents than by external events or natural selection. Stylistic changes may be examples of avalanches of interconnected events. Evidence for self-organized criticality is shown for stylistic evolution in historical pottery styles from New York State and is used to evaluate the nature of a prehistoric pottery typology from the Southwest.     

The Precarity of Young People’s Housing Experiences in a Rural Context

Young people’s housing, economic and labour market circumstances have become increasingly insecure due to the combined effects of the 2007/2008 economic crisis, neoliberal welfare reforms, rising costs of higher education and the shortage of affordable housing. Discussions of young peoples’ experiences in these domains have largely neglected their spatial variability but evidence suggests that young people living in rural parts of the UK have distinctive experiences of housing, which are closely connected to labour markets and educational opportunities. By drawing on qualitative data from young people and housing professionals, this article explores some of these rural distinctions and frames them within theoretical debates about the ‘precariat’. It argues for a more theoretically informed and geographically nuanced understanding of contemporary housing issues as rural youth potentially face greater precarity than their urban peers.     

Sir Reader Bullard,Frank Roberts and the Azerbaijan crisis of 1945–46: Bevin’s officials,perceptions and the adoption of a Cold War mentality in British Soviet Policy

This article evaluates the influence of the Azerbaijan crisis of 1945–46 on evolving perceptions of the Soviet Union within the British Foreign Office. Utilising records from the National Archives and personal papers, it synthesises the history of the Azerbaijan crisis with studies of Britain’s changing Soviet policy, previously focused solely on the Northern Department and Moscow representative Frank Roberts. In so doing, the paper provides an original diplomatic history which argues that, although Europe remained the strategic priority for Foreign Secretary Ernest Bevin, Iranian developments were of greater significance in prompting a perceptual transition from cooperation to Cold War confrontation.     

Dewey’s concept of experience for inquiry-based landscape drawing during field studies

The epistemological and educational philosophy of John Dewey is used as a theoretical basis to analyze processes of knowledge construction during geographical field studies. The experience of landscape drawing as a method of inquiry and a starting point for research-based learning is empirically evaluated. The basic drawing skills are acquired through an online drawing course. The main aim is to foster the self-organized acquisition of relevant skills to explore, describe and reflect on subjective mental and linguistic concepts in relation to scientific landscape models. The results, based on an evaluation of the students’ drawings, their responses to questionnaires and a review of students’ “reflective notes”, indicate that the approach motivated students to learn about the processes which formed the landscape and that the students perceived the method of inquiry after Dewey as a way to overcome cognitive dissonance.     

One for all,or all for oneself? Governance cultures in regional public transport planning

Due to the fragmented organizational landscape characterizing public transport, it is important to study and explore how regional governance of public transport adapts to national institutional reforms. By employing the term ‘governance cultures’ to a comparative case study of regional public transport planning in Sweden, we contribute to theories of governance by cultural sensitization. Combining governance theory with cultural analysis, we apply a cultural perspective to understand the two cases. We conclude that public transport planning in the Stockholm region is defined by ‘negotiations’ between stakeholders, whereas in the Västra Götaland region it is characterized by a governance culture of ‘collaboration’. The evidence from our case studies emphasizes the importance of understanding local governance practices as situated in cultural contexts as well as of viewing governance cultures as an important factor affecting the purpose, degree and outcomes of collaboration in planning practices.