It is proposed that the problem of the relationships between prehistoric art and archaeological context should not be based upon specific examples, but rather upon a global consideration of the stratigraphic sequence known for any given area. This paper addresses this general problem, using the particular data provided by research in the Tadrart Acacus (Libya). The methods used in the field work and the sequence of occupation reconstructed for the entire region are presented. As a specific example, the site of Uan Muhuggiag in the Wadi Teshuinat is discussed. As a result of its deep stratigraphy it is possible to establish precise connections between different artistic ‘styles’ and particular cultural horizons.

This report deals only with the fine pottery since it is this material which provides, in the first instance, the dating for the sites in the survey area. A full report on all the pottery is in preparation.

The fifth season of the UNESCO Libyan Valleys Survey was completed at the end of October 1989. The work of the first three seasons resulted in the development of a model for the socio-economic hierarchy in the area of the Valleys. Two particular types of site (the Farms known as Opus Africanum farms and the Gsur) were considered to be the sites which dominated this hierarchy during different periods of the history of the area. On the basis of the pottery evidence, we established that the Opus Africanum farms were associated with the early period and the Gsur with the later period; there was some indication of decline from around the end of the fourth century.

The aim of the two most recent seasons was to examine particular examples of these two types of site. In 1984 an Opus Africanum farm was examined situated in Wadi el Amud; its occupation began in the second half of the first century AD. Most recently, in 1989, two areas were examined, and these were chosen for research because of the possibility that they were only occupied in the late period: firstly, Wadi Buzra which flows into Wadi Mimoun and secondly Wadi Umm el Kharab which flows into Wadi Nafad.

In this first season several exploratory trenches were sunk with encouraging results. There is a considerable depth of stratigraphy over the whole town, sufficient, it would seem, to preserve substantial remains, and there is evidence of considerable occupation in the medieval Islamic period, as well as some material of Greek and early Roman date. In the 1990 season, it is planned to open a much larger area and begin the systematic controlled excavation of the Islamic levels, and it is hoped that, in the coming years, the combined expertise of this Anglo-Libyan venture will bring to light the town whose importance is hinted at in the historical sources.

The 1988 season of the Society's work at Tolmeta concentrated on drawing the key pottery from the 1978/79 excavations in the North-east Quadrant. These drawings are currently being processed to refine the chronology of the structural phases on this part of the site, and it is hoped that the results will be published in the 1991 volume of Libyan Studies. The opportunity was also taken in 1988 of further examining in some detail stratigraphic sections in House G. A carbon sample taken from one of the rooms has now been C14 dated to the period AD 680-780. Thus settled life in the city would seem to have continued well into the Islamic period.

The Romano-Libyan farm Lm4 includes a ‘barrage’, water control walls and farm buildings. These were built as part of an agro-hydrological farm system at the confluence of the Wadi el Amud and the Wadi Umm el Bagul in the Libyan pre-desert. The farm appears to have functioned in a geomorphological environment not dissimilar to that which prevails today — with occasional rain storms producing overland flow and floods interrupting a dominance of aeolian processes. Field mapping revealed that substantial scatters of midden made up of abraded pottery, bone, and animal dung occur around the buildings. Animals appear to have been kept near to these buildings, which lead to coprolites becoming a very important component of these anthropogenic sediments. Such activity gave rise to significant bioturbation of the sediments, and a notable former vegetation cover. The petrology of the building stones used in the farm buildings is described using petrographic thin section studies. Cavernous weathering and case-hardening are shown to have developed after the stone was incorporated within the building. The size and distribution of these features are shown to relate to the nature of the bedrock used — especially the form and distribution of joints and sedimentary parting planes — as well as the distribution and thickness of the surficial soils and sediments, and the shape and form of the building.

White surface encrustations developing on basalt which had the same ‘reflectance signature’ on digital Landsat imagery as that from the limestone terrain in the Tripolitanian pre-desert are shown at the Wadi Gobbeen to be the thalli of the crustose lichen of the genus Aspicilia. The reproductive structures and ascospores of the lichen are described. The lichen is seen to be aiding the weathering and disintegration of the basalt cobbles. The absence of the thalli on the sides and underneath of cobbles currently resting upon the present land surface may suggest that soil erosion has been rapid in the recent past.

The description and analysis of particle size distributions using log skew Laplace distributions is a new technique designed to overcome various mathematical and computational problems associated with other approaches. This paper presents an application of the method. In particular, it describes fitting log skew Laplace distributions to modern and ancient shoreline sands from Lepcis Magna (near Horns), Tripolitania, with the purpose of discriminating between modern environments and so classifying the ancient samples. Satisfactory discrimination was not always achieved between some of the modern ‘calibration’ shoreline sand samples of known provenance — possibly as a result of the presence of multimodal distributions. One layer in the harbour-infill sequence, previously of unknown provenance, was shown to have collected at, or close to, an ancient shoreline which developed within the ancient harbour. The majority of the ‘ancient’ samples of unknown depositional environments which were excavated from exposures in the Romano-Libyan harbour-infill sands, were shown by this analysis to be of neither beach nor aeolian origin. This conclusion supports field observations which suggested that the greater part of the harbour-infill sequence represented reworked dune palaeosols, developing dune soils and fluvial and lagoonal facies.

Calcreted debris flow breccias which form the lowermost Pleistocene deposits in the Hammadah Al Hamrah region are locally overlain by well cemented conglomerates of the Old Wadi Terraces. These are commonly capped by a younger, mature calcrete which is also found patchily developed on the Tertiary and Mesozoic limestone bedrock. Basalt lava flows rest either on an eroded surface in the conglomerates or directly on the debris flows; however, their relationship to the younger calcrete is rarely seen. In the area north-east of Mizdah a pre-younger calcrete age for the basalts is proposed on the basis of calcrete-filled fissures which invade the topmost part of the lava sequence. Similarity of the Mizdah sequence to that at Wadi Ghan in the Jabal Nafusah supports correlation of the conglomerates and basalt with Unit Q2 and the younger calcrete event with the upper calcrete of the Jifarah/Wadi Ghan areas. The calcreted breccia/debris flow deposits in turn correlate with Unit Q1 and the lower calcrete.

The conventional view is that Malta has been on the ‘forgotten frontier’ of Christian maritime resistance to Islamic expansionism since the Islamic invasions of North Africa in the seventh century. The limited archival and archeological evidence suggests that, up to the arrival of the Order of the Knights of St John of Jerusalem in Malta in 1530, this picture is not accurate. The Islamic occupation of the Maltese archipelago in 870 created a cosmopolitan Muslim society which persisted until the mid-thirteenth century, despite the Norman conquest of the region in 1090. Indeed, the formal end of Muslim society in Malta only came in 1224, as a side-result of the Hohenstauffen suppression of a Muslim rebellion in Sicily.

Even under the Order of St John contacts with the Muslim world were far closer than is conventionally supposed. The Grand Master of the Order maintained close contacts with the Qaramanlis in Tripoli and the Beys of Tunis during the eighteenth century, despite the continuation of the corso. In reality, contacts had always existed and had been recognised as essential by the Holy See because Malta could not sustain its population once it had exceeded 10,000 persons. Sicily, the obvious source of supply, often exerted undesirable political pressure and the Barbary coast was the only other alternative. The main legacy of the close contacts between Malta and the North African Muslim world, however, is to be found, even today, in the Maltese language, which is really a Medieval variant of North African Arabic.