THE WRITING'S IN THE WALL: A REVIEW OF NEW PRELIMINARY APPLICATIONS OF ELECTRICAL RESISTIVITY TOMOGRAPHY WITHIN ARCHAEOLOGY

Natural processes are known to cause significant damage to archaeological monuments. In fact, the key to understanding the decay of building materials is the internal movement of water through the mineral matrix, which influences the distribution of chemical, physical and biological deterioration processes. Electrical resistivity tomography (ERT) was traditionally used as a surveying tool within archaeology, but a new high‐resolution technique that accurately traces the movement of moisture in building materials could provide a vital tool for understanding the decay of many archaeological monuments. This paper considers current progress, the shift of ERT from soil to rock research and the impact that this development could have on future conservation, using Hertford College (Oxford) and Neolithic rock art (Golden Gate Reserve, South Africa) as case studies.     

COMPUTED TOMOGRAPHY AND COMPUTED RADIOGRAPHY OF LATE BRONZE AGE CREMATION URNS FROM DENMARK: AN INTERDISCIPLINARY ATTEMPT TO DEVELOP METHODS APPLIED IN BIOARCHAEOLOGICAL CREMATION RESEARCH

To improve the methods used to study prehistoric cremation rituals, cremation urns from the Danish Late Bronze Age were examined using computed tomography and computed radiography (digital X‐ray). During micro‐excavation, the digital images were used as a registration tool. Our results suggest that osteological ageing and sexing are more accurate when combining CT images with excavated remains. Digital volume rendering further enables a compromised estimation of the original cremation weight. Micro‐excavation is clearly a primary cause of bone fragmentation. Cremated remains affected by lower cremation intensity show markedly poorer preservation and recovery than do white calcined fragments. Thus post‐excavation estimations of cremation intensity are systematically biased.     

NEUTRON TOMOGRAPHIC ASSESSMENT OF INCISIONS ON PREHISTORIC STONE SLABS: A CASE STUDY FROM WONDERWERK CAVE,SOUTH AFRICA*

This study presents the application of neutron tomography to the analysis of ironstone slabs found in a late Earlier Stone Age context (Fauresmith industry) at the back of Wonderwerk Cave, Northern Cape Province, South Africa. These slabs have markings on the surface that might be anthropogenic, and thus significant to understanding the emergence of human symbolic behaviour. Neutron tomography proved to be an effective tool for distinguishing surface incisions from lines that are the expression of internal fissures in the rock.     

USING OPTICAL COHERENCE TOMOGRAPHY TO EXAMINE THE SUBSURFACE MORPHOLOGY OF CHINESE GLAZES

Optical coherence tomography (OCT), a new method for ceramics research, is a nondestructive, three‐dimensional tomography system, which provides subsurface morphology visualization of samples based on the refractive index or dielectric constant differences in the target specimen. In this study, seven shards from different Chinese kilns of Song and Yuan dynasties (10–14th centuries) were scanned to visualize the subsurface morphology of their glazes. The images revealed unique phase assemblage modes in different samples. The results suggest OCT may be used to identify ceramics and provide information about their manufacturing technology.     

Stone Tool-Making and Brain Activation: Position Emission Tomography (PET) Studies

This study introduces to archaeology a new experimental technique for examining the relationship between stone tool-making and brain function. The principal focus of this exploratory study was the development of effective methods for the identification and examination of the regions of the modern human brain recruited during the manufacture of simple (Oldowan or Mode I) stone tools. The functional brain imaging technique employed, Positron Emission Tomography (PET), examines task-related brain activity by assessing changes in regional cerebral blood flow during specific tasks. The single-subject study reported here represents a heuristic, initial exploration of this subject. Results indicate that during stone tool-making there was heavy activation of cortical and subcortical regions of the brain associated with motor and somatosensory processing. Especially interesting was the high degree of activation in areas known to be involved with complex spatial cognition requiring integration of diverse sensory inputs (e.g. vision, touch, and proprioception, or sense of body position and motion). Expansion of such higher-order association areas has been particularly important during the course of human evolution. This single-subject pilot study demonstrates the application of the PET brain imaging technique to the study of early stone technologies and suggests hypotheses to be tested in more comprehensive studies in the future.     

DID NEANDERTHALS PLAY MUSIC? X‐RAY COMPUTED MICRO‐TOMOGRAPHY OF THE DIVJE BABE ‘FLUTE’*

Archaeological evidence for wind musical instruments made by modern humans has been well established from the Upper Palaeolithic in Europe. Musical instruments evidently made by Neanderthals have not been found so far. The most controversial object is a juvenile cave bear femur with two complete holes, found in 1995 in the Middle Palaeolithic layers of the Cave Divje babe I, Slovenia. The bone was interpreted as a possible Neanderthal ‘flute’, but some scholars have firmly rejected this hypothesis on the basis of taphonomic observations, suggesting a carnivore origin for the holes. Here, we show the results of X‐ray computed micro‐tomography (mCT) performed on the Divje babe I ‘flute’. Our analyses demonstrate that there were originally four holes, possibly made with pointed stones and bone tools. Most surface modifications near the holes, previously interpreted as effects of carnivore gnawing, are post‐depositional marks. Furthermore, a thin layer has been removed around one of the complete holes, producing a flat surface, possibly to facilitate perforation. The new data show that a Neanderthal manufacture of the object cannot be ruled out.     

INVESTIGATION OF THE CONTENT OF ANCIENT TIBETAN METALLIC BUDDHA STATUES BY MEANS OF NEUTRON IMAGING METHODS

Many important cultural and religious objects from Asia consist of outer metallic shapes, usually bronze, which fully enclose inner contents made of organic materials such as wood, bark, paper, textile, plants and others. Bronze and other metallic materials, such as copper and silver, are generally more transparent to neutrons than to X‐rays. However, organic materials are less transparent to neutrons than to X‐rays and therefore organic materials, enclosed by metallic materials, can be made visible with neutrons. Therefore, neutron imaging (radiography and tomography) was found to be an ideal tool for the inspection of objects that consist of metal outside and organic materials inside. This has been successfully demonstrated here with four metallic Tibetan Buddha statues, providing archaeometry with a powerful new tool. The first successful applications of this novel technique are described in this article. Further possible and useful applications of neutron imaging of cultural objects are outlined.     

The Use of Optical Coherence Tomography for Monitoring the Subsurface Morphologies of Archaic Jades

We demonstrate the use of the Optical Coherence Tomography (OCT) technique for non‐invasive scanning of the subsurface morphologies of jade objects. The two‐dimensional tomography images show the refractive index or dielectric constant variations in the samples, reflecting their structures. Three samples of archaic jade objects from the Qijia and Liangzhu cultures in China are scanned in order to understand the subsurface morphologies of the naturally whitened jades. Also, two jade objects with artificial treatments (burning) are scanned and compared with the original materials in subsurface structures. In the original objects, the jade materials can generally be quite transparent, such that the backscattering intensity is weak, although the large‐scale (tens of microns or larger) subsurface morphology can be clearly observed. After burning, small‐scale (smaller than a few microns) structures are formed and the backscattering intensity is enhanced. In this situation, the large‐scale structures may be preserved or even newly generated. On the other hand, in an archaic object with natural whitening, small‐scale structures are also formed. Hence, the deeper distributions of significant backscattering intensity are observed, when compared with the unwhitened objects. Nevertheless, the large‐scale features diminish during the whitening process. With OCT scanning, such differences in subsurface morphology can provide us a valuable reference for authenticating archaic jade objects.     

X‐RAY SUB‐MICRON TOMOGRAPHY AS A TOOL FOR THE STUDY OF ARCHAEOLOGICAL WOOD PRESERVED THROUGH THE CORROSION OF METAL OBJECTS

Wood preserved in the corrosion layer of two early medieval iron objects was examined using X‐ray tomography. A state‐of‐the art multi‐resolution X‐ray tomography set‐up ( http://www.ugct.ugent.be ) provided virtual cross‐sections of the archaeological wood samples at sub‐micron resolution. These were compared with scans of samples of similar modern wood. These scans demonstrate the power of sub‐micron X‐ray tomography for wood identification, although the process of mineralization pushes this technique to its limits. Furthermore, this technique facilitated appraisal of the mineral content of the archaeological wood, which is useful in selecting the most appropriate strategy for the (preventative) conservation of the archaeological object.