Wendy Matthews

The use of FT-IR as a screening technique for organic residue analysis of archaeological samples

A range of archaeological samples have been examined using FT-IR spectroscopy. These include suspected coprolite samples from the Neolithic site of Catalhöyük in Turkey, pottery samples from the Roman site of Silchester, UK and the Bronze Age site of Gatas, Spain and unidentified black residues on pottery sherds from the Roman sites of Springhead and Cambourne, UK. For coprolite samples the aim of FT-IR analysis is identification. Identification of coprolites in the field is based on their distinct orange colour; however, such visual identifications can often be misleading due to their similarity with deposits such as ochre and clay. For pottery the aim is to screen those samples that might contain high levels of organic residues which would be suitable for GC-MS analysis. The experiments have shown coprolites to have distinctive spectra, containing strong peaks from calcite, phosphate and quartz; the presence of phosphorus may be confirmed by SEM-EDX analysis. Pottery containing organic residues of plant and animal origin has also been shown to generally display strong phosphate peaks. FT-IR has distinguished between organic resin and non-organic compositions for the black residues, with differences also being seen between organic samples that have the same physical appearance. Further analysis by GC-MS has confirmed the identification of the coprolites through the presence of coprostanol and bile acids, and shows that the majority of organic pottery residues are either fatty acids or mono- or di-acylglycerols from foodstuffs, or triterpenoid resin compounds exposed to high temperatures. One suspected resin sample was shown to contain no organic residues, and it is seen that resin samples with similar physical appearances have different chemical compositions. FT-IR is proposed as a quick and cheap method of screening archaeological samples before subjecting them to the more expensive and time-consuming method of GC-MS. This will eliminate inorganic samples such as clays and ochre from GC-MS analysis, and will screen those samples which are most likely to have a high concentration of preserved organic residues.

The microstratigraphy of middens: capturing daily routine in rubbish at Neolithic Çatalhöyük, Turkey

Microstratigraphy — the sequencing of detailed biological signals on site — is an important new approach being developed in the Çatalhöyük project. Here the authors show how microscopic recording of the strata and content of widespread middens on the tell are revealing daily activities and the selective employment of plants in houses and as fuel. Here we continue to witness a major advance in the practice of archaeological investigation.

Sub-surface terahertz imaging through uneven surfaces: visualizing Neolithic wall paintings in Çatalhöyük

Portions of Neolithic paintings at Çatalhöyük, Turkey, are hidden under uneven covering layers of plaster. Traditional terahertz data analysis has proven unsuccessful at subsurface imaging of these paintings. An imaging technique is presented, based around Gaussian beam-mode coupling, to visualize the obscured painting.

Rapid characterisation of archaeological midden components using FT-IR spectroscopy, SEM-EDX and micro-XRD

Samples taken from middens at the Neolithic site of Catalhöyük in Turkey have been analysed using IR spectroscopy backed up by powder XRD and SEM-EDX. Microcomponents studied include fossil hackberries (providing evidence of ancient diet and seasonality), mineral nodules (providing evidence of post-depositional change) and phytoliths (mineralised plant cells, providing evidence of usage of plant species). Finely laminated ashy deposits have also been investigated allowing chemical and mineralogical variations to be explored. It is found that many layers which appear visually to be quite distinctive have, in fact, very similar mineralogy.

Analysis of wall plasters and natural sediments from the Neolithic town of Çatalhöyük (Turkey) by a range of analytical techniques.

Wall plaster sequences from the Neolithic town of Çatalhöyük have been analysed and compared to three types of natural sediment found in the vicinity of the site, using a range of analytical techniques. Block samples containing the plaster sequences were removed from the walls of several different buildings on the East Mound. Sub-samples were examined by IR spectroscopy, X-ray diffraction and X-ray fluorescence to determine the overall mineralogical and elemental composition, whilst thin sections were studied using optical polarising microscopy, IR Microscopy and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results of this study have shown that there are two types of wall plaster found in the sequences and that the sediments used to produce these were obtained from at least two distinct sources. In particular, the presence of clay, calcite and magnesian calcite in the foundation plasters suggested that these were prepared predominantly from a marl source. On the other hand, the finishing plasters were found to contain dolomite with a small amount of clay and no calcite, revealing that softlime was used in their preparation. Whilst marl is located directly below and around Çatalhöyük, the nearest source of softlime is 6.5km away, an indication that the latter was important to the Neolithic people, possibly due to the whiter colour (5Y 8/1) of this sediment. Furthermore, the same two plaster types were found on each wall of Building 49, the main building studied in this research, and in all five buildings investigated, suggesting that the use of these sources was an established practice for the inhabitants of several different households across the site.

Late Holocene droughts in the Fertile Crescent recorded in a speleothem from northern Iraq

Droughts have had large impacts on past and present societies. High-resolution paleoclimate data are essential to place recent droughts in a meaningful historical context and to predict regional future changes with greater accuracy. Such records, however, are very scarce in the Middle East in general, and the Fertile Crescent in particular. Here we present a 2400 year long speleothem-based multiproxy record from Gejkar Cave in northern Iraq. Oxygen and carbon isotopes and magnesium are faithful recorders of effective moisture. The new Gejkar record not only shows that droughts in 1998–2000 and 2007–2010, which have been argued to be a contributing factor to Syrian civil war, were extreme compared to the current mean climate, but they were also superimposed on a long-term aridification trend that already started around or before 950 C.E. (Common Era). This long-term trend is not captured by tree ring records and climate models, emphasizing the importance of using various paleoclimate proxy data to evaluate and improve climate models and to correctly inform policy makers about future hydroclimatic changes in this drought-prone region.

Humans and fire: Changing relations in early agricultural and built environments in the Zagros, Iran, Iraq

Fire-centred studies have recently been highlighted as powerful avenues for investigation of energy flows and relations between humans, materials, environments and other species. The aim in this paper is to evaluate this potential first by reviewing the diverse theories and methods that can be applied to investigate the ecological and social significance of anthropogenic fire, and second by applying these to new and existing data sets in archaeology. This paper examines how fire-centred approaches can inform on one of the most significant step-changes in human lifeways and inter-relations with environment and other species – the transition from mobile hunting-gathering to more sedentary agriculture in a key heartland of change, the Zagros region of Iraq and Iran, c. 12,000–8,000 BP. In the review and case studies multiple links are investigated between human fire use and environment, ecology, energy use, technology, the built environment, health, social roles and relations, cultural practices and catastrophic events.

Using experimental archaeology and micromorphology to reconstruct timber-framed buildings from Roman Silchester: a new approach

Abstract Determining the internal layout of archaeological structures and their uses has always been challenging, particularly in timber-framed or earthen-walled buildings where doorways and divisions are difficult to trace. In temperate conditions, soil-formation processes may hold the key to understanding how buildings were used. The abandoned Roman town of Silchester, UK, provides a case study for testing a new approach that combines experimental archaeology and micromorphology. The results show that this technique can provide clarity to previously uncertain features of urban architecture.

Analysis of Red Pigments from the Neolithic sites of Çatalhöyük in Turkey and Sheikh-e Abad in Iran

Samples containing red pigment have been collected from two different archaeological sites dating to the Neolithic (Çatalhöyük in Turkey and Sheikh-e Abad in Iran) and have been analysed by a range of techniques. Sub-samples were examined by IR spectroscopy and X-ray diffraction, whilst thin sections were studied using optical polarising microscopy, synchrotron based IR microscopy and environmental scanning electron microscopy with energy dispersive X-ray analysis. Thin layers of red paint in a wall painting from Çatalhöyük were found to contain ochre (hematite and clay) as well as an unexpected component, grains of red and colourless obsidian, which have not been identified in any previous studies of the wall paintings at Çatalhöyük. These small grains of obsidian may have improved the reflective properties of the paint and made the artwork more vivid in the darkness of the buildings. Analysis of a roughly shaped ball of red sediment found on a possible working surface at Sheikh-e Abad revealed that the cause of the red colouring was the mineral hematite, which was probably from a source of terra rossa sediment in the local area. The results of this work suggest it is unlikely that this had been altered by the Neolithic people through mixing with other minerals.

Early animal management strategies during the Neolithic of the Konya Plain, Central Anatolia: integrating micromorphological and microfossil evidence

ABSTRACT This paper examines the contribution of microscopic multi-proxy approaches to the study of early husbandry practices and animal diet by integrated micromorphological, phytolith, and calcitic dung spherulite analyses of midden deposits at the three neighbouring Neolithic sites of Boncuklu (9th–8th millennium cal BC), Pınarbaşı (7th millennium cal BC) and Çatalhöyük (8th–6th millennium cal BC) in the Konya Plain, Central Turkey. The results reveal considerable chronological and contextual variation in human-animal inter-relations in open areas between different communities and sites. At Boncuklu, middens display well-defined areas where phytoliths and substantial accumulations of omnivore faecal matter low in spherulite content have been identified. By contrast, open spaces at the Late Neolithic campsite of Pınarbaşı comprise large concentrations of herbivore dung material associated with neonatal ovicaprine remains from spring birthing. Here, the deposits represent repeated dung-burning events, and include high concentrations of dung spherulites and phytoliths from wild grasses, and leaves and culms of reeds that, we suggest here, derive from fodder and fuel sources. Late middens at Çatalhöyük are characterised by thick sequences derived from multiple fuel burning events and rich in ashes, charred plants, articulated phytoliths – mainly from the husk of cereals, as well as the leaves and stems of reeds and sedges – and omnivore/ruminant coprolites, the abundance of the latter declining markedly in the latest levels of occupation. The application of this integrated microscopic approach to open areas has contributed to unravelling the complexity of formation processes at these sites, providing new insights into herding practices, diet, and the ecological diversity of Neolithic communities in Central Anatolia.