THE APPLICATION OF CLIFF DEGRADATION MODELS FOR ESTIMATION OF THE INITIAL HEIGHT OF RAMMED‐EARTH WALLS (POR‐BAJIN FORTRESS,SOUTHERN SIBERIA,RUSSIA)

The main objective of this study is to recover the initial geometry of earthen walls from the shape of wall remains. The original parameters of the walls have been estimated by fitting the field‐measured profiles with the theoretical shape predicted by the model. We estimate: (i) the initial wall height (between 2 and 3 m); (ii) their shape (vertical or nearly vertical); and (iii) the time for complete degradation (between 250 and 400 years, depending on wall orientation). We show that this approach yields the best results when the main degradation factor is the temperature gradient, as it is for south‐oriented wall faces.     

MINERALOGY OF BOHEMIAN GREEN EARTH PIGMENT AND ITS MICROANALYTICAL EVIDENCE IN HISTORICAL PAINTINGS

While the most famous historical green earth deposits in Italy and Cyprus were exceptionally rich in celadonite, the deposits near Kadaň, Czech Republic, consisted of thin Fe‐rich celadonite impregnations accompanied by interstratified celadonite/smectite. In superimposed tuffs, smectites become prevalent and their colour changes from forest to olive green. Powder X‐ray microdiffraction and infrared microspectroscopy permit us to distinguish between green earth minerals in microsamples taken from works of art. The Ti contents and the Fe/Mg ratios help to indicate the presence of Bohemian green earth from Kadaň. We found this material in local 18th‐century works of art and also in paintings by Anton Kern (1709–47).     

GEOPHYSICAL SURVEY AT BODEN VEAN,CORNWALL, INCLUDING AN ASSESSMENT OF THE MICROGRAVITY TECHNIQUE FOR THE LOCATION OF SUSPECTED ARCHAEOLOGICAL VOID FEATURES*

A geophysical survey was conducted at Boden Vean, St. Anthony Meneage, Cornwall, over the site of a buried chamber thought to be the remains of a souterrain or fogou. A combination of geophysical techniques was successfully applied including an experimental microgravity survey over the location of the buried chamber itself. Magnetometer survey revealed a complex palimpsest of archaeological activity extending throughout the surrounding landscape, centred on a rectangular ditched enclosure containing the fogou. A series of gravity anomalies were recorded in the vicinity of the latter which were consistent with the collapsed section of the feature recorded by the Cornish Archaeological Unit. Further gravity anomalies suggested the presence of additional void features, possibly related to the extended passages of the fogou.     

Post‐Depositional Elemental Alterations in Pottery: Neutron Activation Analyses of Surface and Core Samples*

From 38 sherds with ‘corroded’ surfaces, two samples per sherd were examined using Neutron Activation Analysis, one from the surface and one from the core of each sherd, in order to analyse post‐depositional alterations of minor and trace elements. The most striking effect was that a leaching of Ca could be found at the surface. Another group of elements that is severely affected are the alkali metals, with Cs and Rb showing the strongest changes. A third conspicuous group of elements are the Rare Earth Elements. Finally, the effect of such alterations on a statistical data evaluation to classify pottery according to provenance is investigated.     

ACCESSING PAST BELIEFS AND PRACTICES: THE CASE OF LEMNIAN EARTH*

Lemnian Earth, a medicine in the shape of a stamped clay tablet (sphragis) from Lemnos, northeastern Greece, was much valued in antiquity and in the post‐medieval period as an antidote to poison and a treatment for other ailments. Although it was among the first archaeological materials to be subjected to chemical analysis (in 1807), there is still no clear understanding as to what made Lemnian Earth an effective medicine. We argue that Lemnian Earth, the artefact, was not the same as Lemnian Earth, the raw material. We suggest a composition for the artefact by scrutinizing the documentary evidence for its properties and by considering the geochemical processes that led to the formation of the raw material and the ritual relating to its extraction. The study of the latter highlights the need for archaeological materials scientists to recognize ritual as a possible manifestation of physical and chemical processes carried out within the framework of past beliefs and practices.     

SYNTHESIS AND ACID RESISTANCE OF MAYA BLUE PIGMENT*

Maya blue is an organo‐clay artificial pigment composed of indigo and palygorskite. It was invented and frequently used in Mesoamerica in ancient times (eighth to 16th centuries). We analyse in this paper one of the characteristics of Maya blue that has attracted the attention of scientists since its rediscovery in 1931: its high stability against chemical aggression (acids, alkalis, solvents, etc.) and biodegradation, which has permitted the survival of many works of art for centuries in hostile environments, such as the tropical forest. We have reproduced the different methods proposed to produce a synthetic pigment with the characteristics of the ancient Maya blue. The stability of the pigments produced using either palygorskite or sepiolite has been analysed by performing acid attacks of different intensities. The results are analysed in terms of pigment decolouration and destruction of the clay lattice, revealed by X‐ray diffraction. Palygorskite pigments are much more resistant than sepiolite pigments. It is shown that indigo does not protect the clay lattice against acid aggression. We show that Maya blue is an extremely resistant pigment, but it can be destroyed using very intense acid treatment under reflux.     

THE ORIGIN AND GEOCHEMICAL CHARACTERIZATION OF RED OCHRES FROM THE TITO BUSTILLO AND MONTE CASTILLO CAVES (NORTHERN SPAIN)*

Ochres were the most common source materials for pigments used in Palaeolithic rock art paintings. This work analyses the petrographic and geochemical signatures of different ochre samples from outcrops inside Tito Bustillo Cave and the Monte Castillo Caves using the most common techniques (petrography, XRD, SEM–EDS and ICP–MS) in archaeological pigment characterization studies. The results obtained permit the identification and characterization of the different source ochre types and, furthermore, allow the establishment of mineralogical and geochemical proxies for the study of questions related to ochre characterization, formation processes and provenance.     

MECHANICAL PERFORMANCE OF QUARTZ-TEMPERED CERAMICS: PART II,HERTZIAN STRENGTH,WEAR RESISTANCE AND APPLICATIONS TO ANCIENT CERAMICS*

Mechanical performance of ceramics can be measured by various techniques. Conventional testing usually requires multiple samples of large size and specific geometries and for this reason cannot be usually applied directly to ancient pottery. However, Hertzian strength and wear resistance can be measured on the same specimen, of small size, and it is shown that these tests can describe, to a good approximation, the basic ceramic mechanical propertics (strength and toughness). Therefore, these tests are proposed for use on archaeological specimens. An application on Punic amphorae found in Corinth is presented.     

DETECTING TRENDS IN THE PREDICTION OF THE BURIED PAST: A REVIEW OF GEOPHYSICAL TECHNIQUES IN ARCHAEOLOGY*

Geophysical survey techniques are a highly visible part of the scientific toolkit that is now used by archaeologists. In this paper, the history of the use of geophysical techniques in archaeology will be discussed, as will significant research themes associated with the most widely used prospecting devices. It is apparent that while the use of geophysical techniques is at an all‐time high, there are many key areas where prospecting is rapidly developing. Some of the advances relate to fundamental aspects of the techniques, while others dictate how we undertake survey in the future. There is a movement away from pre‐gridded survey areas towards real‐time GPS for navigation. This allows greater integration, or fusion, of disparate data sources using visualization techniques derived from associated disciplines. The analysis of landscapes has become a major component of the application of new technology and there are many challenges to be tackled, including how to analyse and interpret significant archaeology within large‐scale, data‐rich, multi‐technique investigations. The reflective nature of the review acknowledges the important role of Archaeometry in the development of archaeological geophysics.     

OCCURRENCES OF GREEN EARTH PIGMENT ON NORTHWEST COAST FIRST NATIONS PAINTED OBJECTS*

An analytical study of First Nations painted objects from the Northwest Coast showed that green earth (celadonite) was used as a green pigment by Tlingit, Haida and Tsimshian artists. Green earth appears to have been used less frequently by Heiltsuk and Kwakwa ka ’wakw artists and was not found on Coast Salish or Nuu‐chah‐nulth objects. Microscopical samples of green paint from 82 Northwest Coast objects, as well as several pigment sources and mineral specimens, were analysed using Fourier transform infrared spectroscopy or X‐ray diffraction. Green earth was the most frequently identified green pigment, found in approximately 40% of the samples.