14C dating of ancient rock art: A new application of plasma chemistry

We have developed a new statically operated oxygen plasma method that allows direct¹⁴C dates to be obtained from ancient rock paintings. The method is applicable even to paintings on limestone (CaCO₃) walls. A sample of a pictograph which had naturally spalled offa shelter wall in the Lower Pecos region of Texas was subjected to a low temperature ( 150°C) oxygen plasma to selectively remove the organic carbon-containing material used in the paint as CO₂, without contamination from the limestone substrate. The Zürich EHT accelerator mass spectrometer was then used to determine the radiocarbon age of this prehistoric rock painting. It was successfully dated at 3865 ± 100 years BP, in good accord with the archaeological context which has set the onset of this Pecos River style of pictograph between 4100 and 3200 years BP. The method appears feasible and is applicable to rock art in which organic materials were used in the paint.     

A fast and reliable detection of indigo in historic and prehistoric textile samples

We present a method requiring no sample preparation for the direct identification of indigoid colorants in tiny amounts in ancient historic fabrics using ASAP®‐MS. Exact determinations were completed in less than 1 min. Copyright © 2015 John Wiley & Sons, Ltd.     

Prehistoric terracottas from the libyan tadrart acacus

The specimens studied in the present work consist of five terracotta fragments from an archaeological dig on the Libyan Tadrart Acacus massif, dating back to about 5000-8000 B.C. The specimens were analysed using thermogravimetric analysis (TG, DTG), differential thermal analysis (DTA), thermomechanical analysis (TMA), X-ray diffractometry, IR spectrophotometry and inductively coupled plasma spectroscopy (ICP). Analyses were aimed in particular to determine the most striking aspect of the finds, the difference in colour between the outer surface (reddish) and the darker inner portion of several of the specimens. The other main points investigated and discussed are related to the firing temperature and chemical and mineralogical composition, of terracotta specimens. This revised version was published online in July 2006 with corrections to the Cover Date.     

μ‐Raman spectroscopy of prehistoric paintings from the Abrigo Remacha rock shelter (Villaseca,Segovia, Spain)

The composition of the materials present in prehistoric paintings discovered on the walls of the Abrigo Remacha rock shelter (Villaseca, Segovia, Spain) has been characterised by micro‐Raman spectroscopy. In addition, scanning electron microscopy and energy dispersive X‐ray microanalysis have been used as auxiliary techniques. The results show that haematite (α‐Fe₂O₃) is the main component of the red pigment. Amorphous carbon and paracoquimbite (Fe₂(SO₄)₃.9H₂O) have been detected in the bluish black pigment used in a significant bi‐colour pictograph. This is the first time that this mineral has been discovered in a prehistoric painting. Accretions of whewellite and weddellite form crusts covering most of the painting panel. Different carbonates are the main components of the rocky substrate. The detection of gypsum on the surface of the panel is associated to the flaking process that is affecting the painting panel. Copyright © 2013 John Wiley & Sons, Ltd.     

Raman microscopy of prehistoric paintings in French megalithic monuments

Remains of pictorial decorations in a series of six representative megalithic monuments of Brittany (France) and two French stelae have been studied by micro‐Raman spectroscopy for the first time. Fungal colonies on the painted orthostats made it difficult to obtain in situ Raman spectra of the paint components. Nevertheless, paint micro‐specimens studied in the laboratory by micro‐Raman spectroscopy, X‐ray photoelectron spectroscopy and scanning electronic microscopy combined with energy dispersive X‐ray spectroscopy have made possible to characterise the materials present. The minerals α‐quartz, albite, microcline, muscovite, phlogopite, celadonite, beryl and anatase have been identified in the granitic rocks supporting the paintings, while dolomite and calcite are dominant in the calcareous rocky substrata. Haematite is the main component of the red pictographs, whereas amorphous carbon and manganese oxides/oxihydroxides have been used in the black ones. Calcite, gypsum and amorphous carbon have been detected as additional components of the paint in some cases. Contamination with modern tracing materials (polystyrene and ε‐copper‐phthalocyanine blue) has been detected in several cases. The presence of pigments as decorative elements in megalithic monuments of Western France and its possible relation with those of the Iberian Peninsula create interesting expectations for the knowledge of the European megalithic culture. Copyright © 2015 John Wiley & Sons, Ltd.     

Characterization of ancient lipids in prehistoric organic residues: Chemical evidence of livestock‐pens in rock‐shelters since early neolithic to bronze age

The characterization of ancient lipids from prehistoric sediments (fumiers ) located in a rock‐selter has been possible after the optimization of an analytical method based on the microwave‐assisted extraction and solid‐phase extraction clean‐up step and a final derivatization step followed by gas chromatography with mass spectrometry. Eight sterols and two bile acids were detected just in the partially burned and unburned layers of the fumiers (animal organic residues deriving from manure/dung). The relationship between some of these compounds can be used to distinguish the biogenic origin of the samples, concluding that these strata (from Early Neolithic to Late Chalcolithic/Early Bronze Age) can be classified as ruminant residues. Three main periods of activity are observed over a period of 2000 years: one from 3990 ± 40 before present (4530–4410 calibrated before present) to 4100 ± 40 before present (4820–4750/4730–4510/4470–4450 calibrated before present), the second from 4470 ± 40 before present (5300–4970 calibrated before present) to 5490 ± 30 before present (6310–6275/6230–6220 calibrated before present) and the third from 5880 ± 30 before present (6775–6765/6750–6645 calibrated before present) to 6010 ± 30 before present (6940–6780/6765–6755 calibrated before present). Chemical data obtained are in concordance with the previous results obtained in the area.