Distinguishing between calcites formed by different mechanisms using infrared spectrometry: archaeological applications

Infrared spectrometry is a well-established method for the identification of minerals. Due to its simplicity and the short time required to obtain a result, it can be practiced on-site during excavation using portable infrared spectrometers. However, the identification of a mineral may not be sufficient. For example, a lime plaster floor and a crushed chalk surface have a similar appearance and are composed of the same mineral – calcite. Here we exploit differences in the infrared spectra of geogenic, biogenic and pyrogenic calcites for the identification of each calcite type. The infrared calcite spectrum has three characteristic peaks in the region of 400–4000 cm⁻¹, designated ν₂, ν₃, and ν₄. When a calcite sample is ground, as part of the measurement preparation procedure, some grinding dependent changes will be revealed in the infrared spectrum. With additional grinding, the ν₃ peak narrows and the heights of the ν₂ and ν₄ peaks decrease, when both are normalized to the ν₃ height. By plotting the normalized heights of the ν₂versus the ν₄ of several grindings of the same sample, a characteristic trend line is formed for each calcite type. The trend lines of geogenic calcites have the shallowest slopes and highest ν₄ values when compared to pyrogenic calcites, which can be further divided to ash and plaster/mortar samples. This method can assist in distinguishing between the various calcites, and provide insights into homogeneity and preservation state of the calcitic materials in question.     

Does size matter: the role and significance of cereal grains in the Indus civilization

Cereal grains play a pivotal role in the rise and character of the Indus civilization. Archaeologists have traditionally focused their attention on the large-grained crops of wheat and barley while often minimizing the importance of the smaller-grained millets. Both environmental and cultural variables influence crop selection in the past as well as today. This paper explores the role and significance of cereal grain size during the evolution of the Indus civilization.     

Keeping Ideas in their Place: In Praise of Thin Constructivism

After acknowledging the growing focus on ideas in Political Science and giving two cheers for that development, this paper warns against the concomitant rejection of the importance of materialist factors in explaining stability and change. The argument is illustrated by a focus on recent literature on globalisation and the global financial crisis.     

Building a tephrostratigraphic framework for the Paleolithic of Central Anatolia,Turkey

The Central Anatolian Volcanic Province (CAVP) in Turkey preserves widespread deposits of Quaternary tephra, presently associated with a small but growing number of Paleolithic archaeological sites. We use multivariate analyses of the abundances of a suite of nine major and minor element oxides determined by electron probe microanalysis. From these data, we construct a classificatory model for correlating distal tephra to one of five volcanic edifices or eruptive phases within the CAVP. Application of this model to distal deposits of primary tephra-fall and reworked tuffaceous sediments from the archaeological sites of Körkuyu and Kaletepe Deresi 3 indicates Late to possibly Early Pleistocene ages for the artifact assemblages there, and provides a fundamental tephrostratigraphic framework to examine spatial and temporal variation in hominin behavior comparable to that of other regions, such as eastern Africa.