Characterization of lime carbonates in plasters from Teotihuacan,Mexico: preliminary results of cathodoluminescence and carbon isotope analyses

This study characterizes the degree of calcination of lime in lime plaster samples from Teotihuacan, the capital of a regional state in prehispanic Central Mexico. Lime plaster production consists of multiple steps, from the firing of raw materials to the mixing of lime and aggregate and the final application. While previous studies have focused on the compositional variability, specifically the recipe of lime plasters and mortars, the characterization of lime itself has not been sufficiently addressed. In this study, cathodoluminescence analysis coupled with petrographic and image analyses were employed to examine the degree of calcination of lime. The results of cathodoluminescence petrography were further examined through stable carbon isotope and ¹⁴C measurements. It appeared that the results of cathodoluminescence analysis are consistent with those of other analytical methods and that there are diachronic changes in the degree of calcination of lime among lime plaster samples. This implies changes in the organization of lime production, specifically the consistency in the control of firing temperature.     

The dry tank: development and disuse of water management infrastructure in the Anuradhapura hinterland,Sri Lanka

We identify and offer new explanations of change in water management infrastructure in the semi-arid urban hinterland of Anuradhapura, Sri Lanka between ca. 400 BC and AD 1800. Field stratigraphies and micromorphological analyses demonstrate that a complex water storage infrastructure was superimposed over time on intermittently occupied and cultivated naturally wetter areas, with some attempts in drier locations. Our chronological framework, based on optically stimulated luminescence (OSL) measurement, indicates that this infrastructure commenced sometime between 400 and 200 BC, continued after Anuradhapura reached its maximum extent, and largely went into disuse between AD 1100 and 1200. While the water management infrastructure was eventually abandoned, it was succeeded by small-scale subsistence cultivation as the primary activity on the landscape. Our findings have broader resonance with current debates on the timing of introduced ‘cultural packages’ together with their social and environmental impacts, production and symbolism in construction activities, persistent stresses and high magnitude disturbances in ‘collapse’, and the notion of post ‘collapse’ landscapes associated with the management of uncertain but essential resources in semi-arid environments.