With National Science Foundation support Drs. Tony Wilkinson and McGuire Gibson will continue their archaeological research in the Dhamar region of highland Yemen. The country is divided into better watered highland and more desertic lowland areas and it is in the upland regions that population density is greatest. In their past work the investigators have elucidated a cultural sequence which covers in excess of 5,000 years. They have also examined a complex agricultural landscape which includes extensive terracing, walls, cisterns and water catchment features. The goal of the current phase of the research is to examine the relationships between population change, terrace construction and environmental degradation. They speculate that it was a growing population and increased pressure on the landscape which led to the development of a more efficient terrace form of agriculture and that this in turn actually served to conserve soil and check the environmental consequences most often associated with increased population pressure. To accomplish this work the investigators will focus their attention on five limited test regions. They will use aerial photographs to locate and map terraces and other agricultural features. Through surface survey, and limited excavation they will locate and date archaeological sites to determine rough measures of population change over time. A wide range of analytical methods (phytolithic analysis, soil micromorphology, particle size, detailed C-14 assay and the retrieval of cultural inclusions) will be employed to pinpoint episodes of increased runoff/erosion, intensive cultivation and manuring. In addition, a program of coring and related microfossil analysis will be used to establish an accurate environmental history and chronological framework. Significant settlement sites and other features will be carefully surveyed and recorded. This research is important for several reasons. It will provide information of the history and utility of a widely practiced traditional agricultural technique. It will shed new light on long term human-environment interaction and provide data of interest to both archaeologists and natural scientists.