University of Évora ARCHMAT (ERASMUS MUNDUS MASTER IN ARCHaeological MATerials Science) Mestrado em Arqueologia e Ambiente : Ciencia dos Materiais Arqueologicos Rock paintings and microorganisms – a new insight on Escoural cave Guilhem Mauran m34312 Ana Teresa Caldeira, Universidade de Évora António Candeias, Universidade de Évora Nicola Schiavon, Universidade de Évora Évora, September 2016 This page intentionally left blank Rock paintings and microorganisms – a new insight on Escoural cave Infrared reflectography of charcoal drawings of horses’ heads in Escoural cave. ©Sonia Costa, Hercules Lab., Universidade de Evora, Evora, Portugal. ARCHMAT 2014-2016 Guilhem MAURAN m34312 Table of contents TABLE OF CONTENTS ....................................................................................................................................... I TABLE OF FIGURES ........................................................................................................................................ III TABLE OF TABLES .......................................................................................................................................... III TABLE OF APPENDIXES ................................................................................................................................ IV TABLE OF ABBREVIATIONS .......................................................................................................................... V ACKNOWLEDGEMENTS ................................................................................................................................ VI PART I ESCOURAL AND UPPER PALAEOLITHIC CAVE ART.................................................................................... 8 CHAPTER 1. CAVE ART: THE RISE OF ART? ................................................................................................................. 9 A. Cave art: a phenomenon through space and time ................................................................................. 9 i. Cave art: the semantic issue ............................................................................................................................... 9 ii. Historical context .............................................................................................................................................. 10 B. Symbolism ............................................................................................................................................ 13 i. Art or symbol? .................................................................................................................................................. 13 ii. Cave art’s interpretations ................................................................................................................................. 14 C. Realisation ........................................................................................................................................... 16 i. The support ...................................................................................................................................................... 16 ii. Pictorial techniques .......................................................................................................................................... 17 iii. Pigments’ preparation ...................................................................................................................................... 18 CHAPTER 2. CAVE ART ALTERATION ....................................................................................................................... 21 A. Cultural Heritage biodegradation......................................................................................................... 21 i. Biodegradation ................................................................................................................................................. 21 ii. Biofilm and microorganisms ............................................................................................................................. 24 iii. Identification of the microbial colonies ............................................................................................................ 26 B. Cave art microbiology .......................................................................................................................... 27 i. Hypogean environment .................................................................................................................................... 27 ii. Cave art alteration ............................................................................................................................................ 29 iii. Hypogean microbial metabolism ...................................................................................................................... 31 C. Karstic climate and cave art’s weathering ........................................................................................... 32 i. Day to day cycle ................................................................................................................................................ 33 ii. Yearly cycle ....................................................................................................................................................... 33 iii. Influences of the cycles on the walls’ degradation ........................................................................................... 34 CHAPTER 3. ESCOURAL AN IBERIAN “MARGINAL” CAVE .............................................................................................. 35 A. Context and specificities of Escoural .................................................................................................... 35 i. Description of the cave ..................................................................................................................................... 35 ii. Discovery and recognition ................................................................................................................................ 37 B. Climatic conditions and conservation state of the cave........................................................................ 38 C. The occupations’ sequence of the cave ................................................................................................ 39 i. Human occupation phases of the cave ............................................................................................................. 39 ii. The parietal art’s corpus ................................................................................................................................... 41 PART II THE PARIETAL ART’S ANALYSES ............................................................................................................. 44 CHAPTER 1. PREHISTORIC PALETTE ........................................................................................................................ 45 A. Red pigments ....................................................................................................................................... 45 B. Black pigments ..................................................................................................................................... 46 C. Preparation .......................................................................................................................................... 48 CHAPTER 2. METHODS ....................................................................................................................................... 50 A. Material ............................................................................................................................................... 50 i. Black pigments ................................................................................................................................................. 51 ii. Red pigments .................................................................................................................................................... 51 B. Methods ............................................................................................................................................... 52 i. In situ analysis ................................................................................................................................................... 52 i ii. Micro-samples analyses .................................................................................................................................... 53 CHAPTER 3. RESULTS AND DISCUSSION ................................................................................................................... 55 A. Observation of the drawings and paintings of Escoural ....................................................................... 55 B. Pictorial techniques .............................................................................................................................. 60 C. Pigments’ identification ....................................................................................................................... 65 i. Black pigments ................................................................................................................................................. 65 ii. Red pigments ...................................................................................................................................................