A multi-analytical evaluation of the depositional pattern on open-air rock art panels at "Abrigo del Lince" (Badajoz, Spain)

Microscopic observation correlated with chemical-mineralogical characterization was performed on pigment samples from "Abrigo del Lince" rock art site (V-IV millennium BC), in order to provide contributions to the study of prehistoric schematic art on granite in the province of Badajoz (Spain). The research objectives include the understanding of technological and cultural aspects, as well as of conservation and deterioration issues related to the pictographs. The multi-analytical approach encompasses the integration of microscopic observation, SEM-EDS analysis, micro-Raman spectroscopy, and ATR-FTIR and allowed to achieve a multispectral overview of the samples and to describe their varied composition and the alteration pattern which connects them. The main phases overlying the granitic bedrock and involved in this sequence are as follows: hematite, whewellite, and gypsum. While hematite could be stratigraphically considered the most ancient layer and assigned to the use of red ochre as a pigment, whewellite and gypsum are the main constituent of the alteration layer which forms a patina over the pictographs, due to weathering processes. Finally, the role of biofilms in rock art conservation is discussed, suggesting that, especially for what concern thin and homogenous layers of oxalates, their presence should not be necessarily considered an issue.

The catastrophic floods in the Guadiana River basin since 1500 CE

The task of retrieving information about past flood events is very important to reconstruct flood series data. In this work, a wide range of different sources including newspapers, technical reports, and books was consulted in order to recover information about catastrophic flood events in Badajoz (Spain). A set of 37 catastrophic floods of the Guadiana River that occurred in Badajoz in the winter months (DJFM - December, January, February, and March) have been recovered since 1500 CE. This strong seasonality constrain is due to the important influence of the large-scale circulation patterns in winter affecting the climate of the Iberian Peninsula. Moreover, it is found that there is a clear difference between a higher number of floods in the 19th and 20th centuries and a substantial lower value of floods in the 16th-18th centuries. Finally, we evaluated the long-term evolution and inter-annual variability of the precipitation and the main large-scale atmospheric circulation patterns that govern climate variability in Iberia (NAO and EA modes) for the period 1851-1985. This analysis suggests that most extreme floods observed in this period (26 events) correspond to consecutive months with higher than usual precipitation, driven in part by unusual values of both the NAO and the EA modes of variability.