Bordering the western limits of the Middle Senegal Valley, research at the Diallowali site complex is the most recent set of archaeological excavations to explore the prehistoric societies that developed along this vital river system.
Consisting of 14 individual mounds, grouped among many specialized activity and seasonal sites, the Diallowali site complex site is an important key in unlocking the history of the occupation of West Africa in general and the MSV in particular. Proceeding from the notion that natural and cultural phenomena exist in an inextricably linked, reciprocal relationship, the goals of The Diallowali Archaeological Project are to establish the occupational chronology of the prehistoric sites as well as the paleo-environmental evolution of the broader region.
The team was led by Yale University doctoral candidate Peter Coutros and Tidiane Sow, a doctoral student the University Cheikh Anta Diop in Dakar. Seven masters and undergraduate students also participated in the project, gaining valuable experience with archaeological field techniques. In order to accomplish the stated objectives, the project team used a three part methodology of a) large-scale excavations; b) geophysical prospection; c) topographic mapping.
Diallowali Site complex
A total of 3 units were excavated at the site complex, which yielded more than 4,500 kg of ceramics and 168.09 kg of bones. The main excavation unit (5m x 2.5m), was excavated to a depth of 3.85m and Test Unit 1 (1m x 1m) and Test Unit 2 (1m x 2m) reached sterile soil at 1.415m and 1.5m respectively. From these units marine shell, red and yellow ocher, river shell, stone tools and bone tools were also recovered in large quantities. Dozens of beautifully fashioned beads of ceramic, bone, shells and semi-precious stones were found throughout the units.
The preliminary analysis of the recovered material, in conjunction with site stratigraphy and topographic mapping reveals an extensive, long-term habitation zone. Ceramic studies suggest at least three major decorative phases, quite unique to those in neighboring regions. The precise dates of the occupation are, at this point, unknown, However, several factors (including the paucity of metallic artifacts and the abundance of stone and bone tools) hint at an occupation that may have extended from the Early Iron Age through the terminal Late Stone Age.
Phase three of the Diallowali Archaeological Project consisted of a series of high-precision geophysical surveys around the main site cluster. The aim of the survey was to map of the limits of the site and to identify areas of high-potential that might offer distinct information through future excavations. The team used the powerful Geoscan fluxgate gradiometer FM256 to complete the sub-surface, noninvasive analysis. Two 20m x 20m target areas were partitioned and mapped with a transect separation of 1.0 m and a measurement periodicity of 3 per meter. When the analysis is complete, the results will inform future excavations as well as aid in the interpretation of geophysical surveys of similar contexts. The use of geophysical methods for archeology is new in West Africa and few projects have used them at habitation sites. If the method succeeds, it will surely open up opportunities for future research projects throughout the region.
One of the main goals of the project is determine how ancient populations lived with their environment. However, because neither cultures nor environments are static, we were also interested in how these components changed over time. Two main proxies, flora and fauna remains, were chosen to determine basic paleo-environmental conditions corresponding to the period of human occupation. These remains, soil samples and bones, were collected over the course of excavations at the main site. The pedological study required that a soil sample of 30 oz be taken from each level for floatation, as well as another 2 oz for phytolith analysis. Due to funding restrictions, only a selection of the 60 pollen and phytolith samples will be sent to specialists for further analysis.
Detailed analysis of faunal remains can reveal subsistence patterns, local environments and the interchange between them. At Diallowali, the three excavation units produced an astounding 200 kg of faunal material. As a result, Jessamy Doman, a specialist from Yale University joined the team at the Université Cheikh Anat Diop de Dakar to identify the remains, often down to species level. Very few human remains were found, including teeth and small bone fragments. However, a variety wildlife have been identified, including many species of birds, reptiles, sheep, goats, cows, souidae and many other bovids. Aquatic fauna was also strongly represented, including molluscs, crabs, many species of fish and even a bull shark. Once the analysis is complete, it will be compared with the pollen and phytolith data in order to develop an understanding of what type of environment the early societies along the MSV inhabited.
To analyze more than 4500 kg of ceramics, the team was forced to sub-divide the study into several stream-lined stages. First, on the site, all ceramic sherds smaller than 4cm ceramics were weighed and discarded due to the limited value in seriation. Sherds larger than 4cm were bagged, labeled and left for analysis at base camp. After all the ceramics were washed and dried, they were separated into categories of type and decoration. Sherds with one decorative pattern were separated, counted and weighed, then discarded. All rim sherds, bottle necks, special ceramics (such as handles, figurines, et.) and sherds with multiple decorations were bagged transported to Dakar.
For two months, the research team worked in the Archaeological Laboratory at UCAD-IFAN to complete analysis. The final results will be ready only after all of the data is transcribed and changes in décor and form preferences over time can be quantitatively evaluated. At this point the preliminary results suggest that at least three major phases of ceramic phases can be detected. More detailed information can be deduced only after further refined statistical analysis is conducted.