The integration of chronological and archaeological information to date building construction: an example from Shetland,Scotland, UK

This paper presents new chronological data applied to the problem of providing a date for the construction of a prehistoric building, with a case study from the Old Scatness Broch, Shetland. The innovative methodology employed utilises the combination of radiocarbon and optically stimulated luminescence (OSL) dates with the archaeological information, which includes the stratigraphic relationships of sampled deposits, context information, and evidence relating to the formation of the deposit. This paper discusses the scientific validity of the dates produced, and the advantages that the methodology employed at this site offers for archaeological interpretation. The combined dating evidence suggests that the broch at Old Scatness is earlier than the conventionally accepted dates for broch construction. More broadly it shows the value of integration of the specialists at the planning stages of the excavation. The application of a Bayesian statistical model to the sequences of dates allowed investigation of the robustness of the dates within the stratigraphic sequences, as well as increasing the resolution of the resulting chronology. In addition, the value of utilising multiple dating techniques on the same deposit was demonstrated, as this allowed different dated events to be directly compared as well as issues relating to the formation of the sampled deposit. This in turn impacted on the chronological significance of the resulting dating evidence, and therefore the confidence that could be placed in the results.     

Identification of pastoral sites using stable nitrogen and carbon isotopes from bulk sediment samples: a case study in modern and archaeological pastoral settlements in Kenya

The identification of pastoral sites in the East African archaeological record is problematic. Recently, a method for the identification of degraded livestock enclosure sediments had been developed that takes into account the geoarchaeological indicators of micromorphology, phytolith concentrations and the mineral assemblages. This suite of indicators may not always be present in degraded livestock enclosure sediments. This study presents an additional indicator by which degraded livestock enclosure sediments may be identified, namely the isotopic composition of organic nitrogen measured on bulk sediment samples. We studied a highly controlled ethnoarchaeological sequence of abandoned Maasai livestock enclosure sediments sampled in Rombo area, southern Kenya. The results were compared to archaeological sediments from the Elmenteitan Pastoral Neolithic site of Sugenya, southwestern Kenya, radiocarbon dated to ca. 2000 BP (uncalibrated). The sediments from both sites were studied using all four types of analyses, i.e., micromorphology, mineralogy, phytolith concentrations, and stable carbon and nitrogen isotopic compositions on bulk sediment samples. The results show that in abandoned livestock enclosure sediments of known ages a significant enrichment in the heavy nitrogen isotope (¹⁵N) occurs, and that carbon isotopic compositions may be useful for differentiating cattle from caprine enclosures following their dietary preferences (i.e., grazers vs. browsers). A similar pattern of ¹⁵N enrichment is observed in sediments sampled within the site of Sugenya while sediments sampled outside the site's perimeter are generally depleted in ¹⁵N. The micromorphological, mineralogical and phytolith analyses support the conclusion that the sediments from within the site of Sugenya represent degraded livestock enclosure sediments. The carbon isotopic composition from the degraded dung deposits strongly suggests that livestock kept at Sugenya were cattle. Overall, this study presents new empirical data that can be used for the identification of livestock enclosures, and shows that the isotopic signatures and geoarchaeological indicators can preserve for at least two millennia.     

Solifluction-induced modifications of archaeological levels: simulation based on experimental data from a modern periglacial slope and application to French Palaeolithic sites

The taphonomic study of Petit-Bost, Croix-de-Canard and Cantalouette II, three Palaeolithic sites that were recently discovered near Périgueux and Bergerac (Dordogne, France) in a colluvial context, has enlightened the difficulty of adequately appreciating the relative role of cultural and natural processes in site spatial patterning. Periglacial solifluction was thought to have played a significant role in site formation. Because the nature of the modifications induced by solifluction was still poorly understood, a simulation was made using data of soil movement recorded at La Mortice (French Southern Alps, 3100 m in elevation) in a modern periglacial environment. The results show that, for a knapping location, the first steps of deformation are typified both by a downslope translation of the location center and by an anisotropic diffusion of the artifacts. The knapping spot becomes elongated along the slope, with a dense relic concentration of artifacts in the upslope portion. This type of pattern has been obtained after 100–200 years of simulated displacement according to the climatic and soil conditions that characterise the La Mortice site. The ultimate stages of deformation show that the artifact distribution tends to homogenise on larger surfaces and resemble a random distribution. The ability of the simulated patterns to closely fit those observed in archaeological contexts is evaluated at three sites from Southwestern France. At Petit-Bost, the hypothesis of limited solifluction explains accurately the association of both cultural (artifact concentrations) and natural (artifact preferred orientation) features. At Croix-de-Canard, long-term solifluction can be proposed. By contrast, the simulated patterns do not describe the structures observed on the steeper slopes at Cantalouette II, where the knapping spot transforms into distinct solifluction lobes.     

The in situ preservation of archaeological remains: using lysimeters to assess the impacts of saturation and seasonality

Recent research has studied the effects of seasonal variability on waterlogged burial environments. In a new approach to the study of archaeological contexts, the use of controlled laboratory conditions via lysimeters has enabled new insights into the nature of short term fluctuations in saturation, and the impact that these can have on burial contexts. In addition, the protocols used have facilitated interesting insights into burial environments and the way in which fluctuations in saturation and seasonality can impact on the contained organic components within them.     

Comment on ‘A Bayesian approach to ageing perinatal skeletal material from archaeological sites: implications for the evidence for infanticide in Roman Britain’ by R.L. Gowland and A.T. Chamberlain

In 1993, I published a paper noting that the age distribution of perinatal infants for some Romano-British sites did not conform to a natural mortality pattern but rather showed a pronounced peak at a gestational age corresponding approximately to a full term infant. I interpreted this as suggestive of infanticide, given that the deed is generally carried out immediately after birth. Gowland and Chamberlain have recently published in this journal (J. Archaeol. Sci. 29 (2002) 677) a reconsideration of the problem of Roman infanticide in which they suggest that the peak I observed in the Romano-British perinatal age at death distribution may have been an artefact of the particular ageing technique I used, and they hence call into question the evidence for Roman infanticide. In this comment I argue that their work is seriously flawed and, using a re-analysis of my 1993 data, I demonstrate that the perinatal peak I observed in the Romano-British age distribution is a robust result that supports an interpretation of infanticide.