Late Postclassic lowland Maya archaeology

The archaeology of the Late Postclassic lowland Maya (ca. A.D. 1200–1517) is summarized and reviewed. The history of past research is outlined, and investigations on topics of major scholarly concern are discussed. The current data allow us to present an approximate reconstruction of the events and processes that characterize the period, although the information on many areas and topics is still fragmentary. Research in Maya archaeology has focused heavily on the more spectacular developments of earlier periods, creating the impression that the last few centuries of the prehispanic era were a time of disorganization and decline. New data and interpretations indicate that the Late Postclassic was a dynamic period in which the lowland Maya were moving in new directions, restructuring their society and worldview.     

THE EFFICIENT COMPUTATION OF UNBIASED MAHALANOBIS DISTANCES AND THEIR INTERPRETATION IN ARCHAEOMETRY*

This paper argues for cross-validation to reduce bias in estimating Mahalanobis distances of individuals to groups, a particular problem with small sample sizes. Formulae for the efficient computation of cross-validated distances, which avoid excessive matrix inversion, are given. The use of Mahalanobis distances as measures of consistency, or as indications of outlying values, is described. The little-known technique of gamma plotting is outlined and discussed as an aid to interpreting distances in these terms. Both cross-validation and gamma plotting are illustrated in an example on marble composition.     

A reconsideration of the West African macrolithic conundrum: new factory sites and an associated settlement in the Vallée du Serpent,Mali

Within West African prehistory, perhaps no period remains more mysterious than that between the Terminal Pleistocene and the mid-Holocene. This time period is shared by diverse macrolithic and microlithic industries. The macrolithic phenomenon has remained ill-defined, with most occurrences being generally lumped together as a single group, or attributed to earlier time periods. Recent archaeological investigations in the Vallée du Serpent and southern Gourma regions of Mali have revealed Holocene macrolithic assemblages quite different from the well-known bifacial traditions of Cap Manuel and Manianbougou, but not without parallels from elsewhere in the Sahel and Savanna. The most important of the Vallée du Serpent sites is that of Sirakoro-Ancien, where worked stone aggregations are associated with several rings of laterite cobbles believed to be the remnants of structures. Its lithic industry consists of massive flakes, perhaps removed directly from local outcrops, and smaller flakes from prepared cores as well as formal tools. Geomorphological and archaeological evidence suggests an age of the Vallée du Serpent sites somewhere between 9000 and 6000 bp. A new synthesis based upon sites investigated by the authors and the predominantly Francophone literature is presented in order to shed light upon this neglected portion of African prehistory.

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Résumé Dans toute la préhistoire de l'Afrique occidentale, aucune période ne reste peut-être plus mystérieuse que celle située entre la fin du Pléistocène et le milieu de l'Holocène. Diverses industries macrolithiques et microlithiques se partagent cette période. Le phénomène macrolithique reste mal défini, la plupart des exemples en sont généralement rassemblés en un seul groupe, ou attribués à des périodes antérieures. Des recherches archéologiques effectuées dans les régions de la vallée du Serpent et du sud du Gourma au Mali ont révélé des collections macrolithiques de l'Holocène bien différentes des traditions bifaciales bien connues de Cap Manuel et Manianbougou, mais non sans parallèles ailleurs dans le Sahel et la Savanne. Le plus important des sites de la vallée du Serpent est celui de SirakoroAncien où des agrégats de pierres travaillées sont associés à plusieurs cercles de galets en latérite que l'on pense être des restes de structures. Cette industrie lithique consiste en éclats massifs, peut-être retirés directement de couches géologiques locales, et en éclats plus petits provenant de nucleus préparés ainsi que des outils. Des preuves géomorphologiques et archéologiques suggèrent que les sites de la vallée du Serpent ont entre 9000 et 6000 ans. Une nouvelle synthèse, fondée sur les sites étudiés par les auteurs et des documents principalement en français, est présentée afin d'éclairer cette partie négligée de la préhistoire africaine.

     

The use of wind direction data to predict pollution dispersal around the Port Kembla industrial area,New South Wales

Wind direction data were used to calculate the percentage time during which winds blew over the principal sources of air pollution at Port Kembla into each of the surrounding residential suburbs for each month of 1980. The percentage wind frequencies (PWFs) correlated well with measured concentrations of airborne metals in the suburbs and with measured rates of metal deposition in moss bags located in suburbs adjoining the air pollution sources. PWFs for all suburbs exhibited winter minima and spring-summer maxima, with the highest PWFs being calculated for suburbs south to south-west of the industrial area and the lowest for suburbs lying to the west. Where experimental data are not available, PWFs could provide an indication of air quality for land-use planning and zoning.     

An 18th century boat in Lake Padarn, North Wales

The Llyn Padarn wreck is a bateau style vessel of the late 18th century. Assuming that it is one of the boats built by the quarry company it was constructed between February 1788 and February 1789. If it was built by one of the independent boatmen its date of construction is uncertain, however its excellent state of preservation suggests that it was still relatively new when it sank, and this also would point towards it being one of the company boats. Whatever the date of building, the boat certainly sank between 1788 and 1824, but the quality of the cargo suggests that it was towards the beginning rather than the end of that period. It is of historic interest as one of the few surviving examples of the bateau style of boat building. and it is also one of the best preserved examples of its kind. It also throws some light on the early history of the North Wales slate industry, on the history of travel and transport on Llyn Padarn, and on the lake settlements at Cwm y Glo and Penllyn. The Padarn boat is now being put into E'EG conservation by the National Museum of Wales, and will subsequently be exhibited in the North Wales Quarry Museum at Llanberis. It would be interesting to know what happened to all the other boats which were evidently working on the lakes in the 18th and early 19th centuries. No doubt most were destroyed when their usefulness came to an end, but if one sank there may well be others, and in due course the Welsh Institute of Maritime Archaeology hopes to carry out a remote sensing survey of Padarn using side-scan sonar and low light television. In addition, the upper lake, Llyn Peris, is to be drained in connection with the massive Pump Storate Generating Scheme which has once again turned the derelict quarries into one of the largest civil engineering projects in Europe. It is certain that these two lakes still have secrets to reveal. I would like to thank the staff of the North Wales Quarry Museum for their patient assistance and advice in the preparation of this article; Mr Brian Buckle of North Wales Divers Ltd, Colwyn Bay, for providing me with a copy of his survey of the wreck site; Mr Derwyn Jones, the Welsh Librarian in the University Library, Bangor for bringing to my attention various references to Margaret ferch Evans, and my colleague Mr Emlyn Sherrington for translating certain passages from the Welsh.     

ASSESSING ARMS CONTROL MEASURES: THE HISTORICAL SETTING

The U.S. has since World War II followed a defense policy and strategy that combined traditional national approaches with features especially typical of American attitudes toward war and peace as well as force and power. The deep dilemmas of nuclear deterrence confront the U.S. with an inescapable dilemma, which in turn motivates an increasingly serious arms control policy.