FOSSIL DIATOMS AND THEIR SIGNIFICANCE IN ARCHAEOLOGICAL RESEARCH

Summary. The relationship between environmental archaeology and diatom analysis, a well established technique in palaeoecology, is explored. The development of diatom analysis for palaeoenvironmental reconstruction is briefly considered and flow diagrams are presented to illustrate laboratory techniques. Examples of research in Mexico, North America, Britain and Europe are discussed to illustrate the potential of diatom analysis as a means of assessing human impact on the environment, notably lake water quality, and as a means of elucidating the palaeoenvironmental conditions under which archaeological sediments have accumulated. Consideration is also given to the role of diatom analysis in examining land/sea-level changes, especially those which may have affected prehistoric resource use, and to its significance in the reconstruction of local environments in and around archaeological sites. Finally, the potential of fossil diatoms for provenancing pottery is explored with particular reference to Dutch and Finnish examples.     

VARIETIES AND SOURCES OF ARTEFACTUAL OBSIDIAN IN THE MIDDLE STONE AGE OF THE MIDDLE AWASH,ETHIOPIA*

Recent investigation of the geochemical provenance of obsidian artefacts from spatially and temporally variable archaeological sites in Ethiopia has shown the diversity of geological sources and concomitant differences in the transport of raw material to archaeological sites, thus allowing reconstruction of the utilization of raw material by early hominids as well as recent humans. We recognize 30 compositionally different obsidians that were used at the Middle Stone Age (MSA) archaeological sites of Aduma (A8), Halibee Herto, Aladi Springs and Porc Epic in the Middle Awash region. Probable sources of nine of these obsidians are Adokoma, Ayelu, Ida'ale, Assebot, Asboli, Gira‐Ale and Kone. Many compositional types are confined to a single site, but others are shared between sites, although shared obsidians between sites more than 300 km apart are exceptional.     

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.     

Sources of archaeological volcanic glass in the Primorye (Maritime) Province,Russian Far East*

Geochemical studies of volcanic glasses (obsidians and perlites) from geological outcrops (N = 80) and archaeological collections (N = 110) were performed in order to determine source provenance in Primorye (Russian Far East), using neutron activation analysis and X‐ray fluorescence spectrometry. Three major sources of archaeological volcanic glass were identified, two relatively local and one more remote. Several minor sources detected in the archaeological assemblage have not been located. This study suggests that long‐distance obsidian exchange between Primorye and adjacent North‐East Asia has existed since c. 10 000 bp .     

ON THE INFLUENCE OF DRYING AND FIRING OF CLAY ON THE FORMATION OF TRACE ELEMENT CONCENTRATION PROFILES WITHIN POTTERY*

On experimentally fired briquettes made of five chemically and mineralogically different clays, trace element concentration profiles from the centre to the surface of the briquettes have been measured by Neutron Activation in order to examine if drying and firing of the clays lead to a mobilization and subsequent migration of single components within a sherd. Mineralogical changes during firing have been determined by X‐ray diffraction. Generally, no such migration could be found. For two clays, arsenic was lost from the briquette during firing, forming non‐constant concentration profiles. If NaCl is present in the clay paste, sodium migrates towards the surface. Additionally, in the special case in which the presence of NaCl coincides with that of calcite, the heavier alkali elements evaporate, forming significant concentration profiles within the sherd.     

PROVENANCE DETERMINATION OF LAVA FLAGSTONES FROM THE ROMAN ‘VIA CONSOLARE FLAMINIA’PAVEMENT (CENTRAL ITALY) USING PETROLOGICAL INVESTIGATIONS*

Trachyte lava flagstones from the northernmost stretch of the Roman ‘Via Consolare Flaminia’pavement and trachyte lavas from the most exploited quarries in Roman times were compared from a petrological point of view. ‘Via Consolare Flaminia’was the most important route used by the Romans to reach northern Italy and all the northern provinces of the Empire. A provenance for the flagstones as coming from the trachyte quarries of the Euganean Hills (Veneto region, northern Italy) is suggested by the similarity of both the fundamental mineral assemblage and the major trace element geochemistry. The location of the quarries of the Euganean Hills next to the harbours of the northern Adriatic Sea strongly supports the hypothesis that the Romans carried the flagstones by ship towards the coasts of the central Adriatic Sea.     

TESTING ASSUMPTIONS OF NEUTRON ACTIVATION ANALYSIS: COMMUNITIES,WORKSHOPS AND PASTE PREPARATION IN YUCATAN,MEXICO*

Contemporary pottery and raw materials (N= 170) from three workshops in Ticul, Yucatán, were analysed by neutron activation to test the hypothesis that individual workshops that used their own clay sources could be identified by their pottery. Although the data failed to confirm the hypothesis, the results reinforced previous conclusions about the relationship of local communities of potters to the chemical patterning of pottery made in these communities.     

IBERIAN CERAMIC PRODUCTION FROM BASTI (BAZA,SPAIN): FIRST GEOCHEMICAL,MINERALOGICAL AND TEXTURAL CHARACTERIZATION

Ceramic fragments from the archaeological excavation of the Iberian–Roman city of Basti (Spain) were studied from a geochemical point of view and by applying a statistical tool to X‐ray fluorescence data to discover similarities between ceramic materials. The analysis of these samples was completed by performing a mineralogical analysis, textural observation, and by characterizing the porous system and the colour of the pieces. Our results enabled us to identify the source area of the clayey raw material in the surroundings of Basti and to estimate the firing temperature of the ceramics. Differences in the chemistry were confirmed by characteristics of the pastes and the mineralogical composition of the pieces. Some samples show black cores, which would suggest the presence of organic matter in the raw material and fast firing of the ceramics. The main types of temper were quartz grains and gneiss fragments, although carbonate grains were also identified. Our evidence suggests that most of the samples were well fired. New silicate phases were found to be present in several samples. The mercury intrusion porosimetry verified and confirmed the firing temperature of non‐carbonated samples. Colorimetry showed that the colour of the ceramics varied according to the amount of CaO that they contained.     

‘GRANITO DEL FORO’ AND ‘GRANITO DI NICOTERA’: PETROGRAPHIC FEATURES AND ARCHAEOMETRIC PROBLEMS OWING TO SIMILAR APPEARANCE

Granitoid rocks were among the stone materials most frequently used for columns and pillars during the Roman period. When employed in Rome and the Mediterranean provinces, they were mainly quarried in Egypt, in Asia Minor and in Italy. Some of these rocks show very similar macroscopic features, so it is often very difficult to tell them apart with the naked eye. This is the case with the ‘Granito del Foro’ (or Marmor Claudianum), from the Gebel Fatireh, in the Eastern Desert, and the ‘Granito di Nicotera’ (Calabria), both exploited from the first century ad onwards. Both feature medium grain size and a white‐greyish colour with black patches. In order to obtain a certain microscopic and geochemical discrimination of these rocks, and to provide the first known petrographic classification of the ‘Granito di Nicotera’, a comprehensive mineralogical, petrographic and geochemical investigation was performed on several samples from the quarry. The results were compared with the corresponding data known for Marmor Claudianum in the literature. Good discrimination between the granites is possible, mainly on the basis of modal mineralogy and geochemical characteristics. The ‘Granito del Foro’ contains hornblende, while the ‘Granito di Nicotera’ contains muscovite, and has a distinctive peraluminous index and trace element abundances.     

PETROGRAPHIC AND GEOCHEMICAL EVIDENCE FOR LONG‐STANDING SUPPLY OF RAW MATERIALS IN NEOLITHIC POTTERY (MENDANDIA SITE,SPAIN)

Pottery from the Neolithic Mendandia site has been studied. The radiocarbon dating of the site corresponds to a range of dates from 7488–7546 cal bc to 5283–5437 cal bc : the first occurrence of pottery is dated at 5968–6040 cal bc for the lower level III, and up to 5386–5560 cal bc for level II. The antiquity of the potsherds places them within the oldest pottery production sequences in the Iberian Peninsula, which adds to the interest of this study. Ten potsherds from level II and five from level III are analysed for their petrographic and chemical characterization. The petrographic data show two different methods of raw materials manufacture—intentionally tempered pottery (ITP), using calcite and/or limestone and grog, and naturally or non‐intentionally tempered pottery (NTP). According to the matrix paste features, on the basis of the amount, shape, and average or size range of the mineral inclusions, clayed (type A) and sandy (type B) paste types were established and related to two different source areas. The chemical features also indicate two raw material sources and are in agreement with the petrographic paste types. The absence of significant chemical and mineralogical differences between the pottery from levels II and III suggests two contrasting areas for raw materials supply that lasted for at least 600 years.