Shell middens in Senegal: validating photo interpretations in the field

Nicolas S. E. Sisset Sagna 

IFAN, University of Cheikh Anta Diop of Dakar

Significant work on shell mounds has been undertaken in Senegal within the MAEASaM project. Senior Technician Nicolas Sagna is one of the MAEASaM project members based at the Institut fondamental d’Afrique noire (IFAN) of the Cheikh Anta Diop University of Dakar. In this article, he summarises a recent mission carried out with colleagues from the IFAN Geography laboratory: Dr Meissa Fall (geographer), Dr Modou Ndiaye (geographer), Abdou Aziz Faye (PhD student geographer) and Tamsir Maïga (Driver).

Remarkable for their size, shell mounds are accumulations of mollusc shells of human origin dating back more than 2000 years (Descamps & Thilmans 1979, 2006; Bocoum et al. 2010; Camara 2010; Diouf 2010, 2019; Hardy et al. 2016; Camara et al. 2017; Holl 2022). Estimated to number 218 sites, some of the shell middens are surmounted by burial mounds, hence their status as sacred sites, and of archaeological importance. All are classified as national heritage sites. Among these are 96 sites located in the Saloum Delta, which have been classified UNESCO World Heritage. Unfortunately, shell midden sites located in the lagoon/island area of Joal-Fadiouth are threatened by human activity and by rising water levels due to the geomorphology of the surrounding area.

From 6th to 16th September 2022, the IFAN team undertook a field trip to Joal-Fadiouth, a town located on Senegal’s Petite Côte in the department of Mbour, region of Thiès. Famous for having given Senegal its first president, Léopold Sédar Senghor, Joan-Fadiouth is also known for its Islamic-Christian cemetery constructed on a shell mound. The aim of the mission was to investigate the impact of dykes that were constructed to protect the freshwater channels from salt water. At the same time, the mission offered MAEASaM the opportunity to validate the results of work that Senegalese team members had been carrying out to identify shell mounds through remote sensing and visual analysis (photo interpretation of Google Earth images and QGIS). It was also the right moment to verify the accuracy of “legacy data”, that is, data that the MAEASaM team had been collecting from published sources (Martin & Becker 1977; Diouf 2017).

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Validating the results of the remote sensing work meant reaching the sites by canoe through the bolongs (river channels). GPS points and photos were taken. Due to time constraints, not all the sites identified by remote sensing could be visited, but six sample sites were validated as being shell middens.

Six additional sites were recorded with their geographic coordinates, thanks to published data. Of these sites, two were found in the location stated in the publication Inventaire des sites protohistoriques de la Sénégambie (Martin & Becker 1977). Site number 3 is located about half-way between two other shell mounds, around 257m from the first and 278m from the second. Site number 4 corresponds to a mound located just outside Joal in the direction of Fadial, to the right of the bridge. Two other sites were not found in the locations indicated in the publication: site number 5 lies about 290 m away and is probably the island of Fadiouth, which itself is a shell mound. As for site number 6 (Faboura), the legacy data positions it at 1 km from Faboura, a shell mound, which might perhaps extend as far as the coordinates noted in the publication. Site 1 and 2 have probably been absorbed by urban expansion, but it was not possible to visit the locations to confirm or refute the theory.

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Other sites of a different nature have been recorded and seem worthy of further exploration. Among these is the small island of Ngoussé Diokhé (see image above), a sacred site about 30m by 18m made up of shell middens on which a baobab tree grows. From a cultural point of view, Ngoussé Diokhé is part of the string of sacred sites listed in the Joal-Fadiouth area and constitutes very important cultural heritage for both the local citizens and Senegalese in general.

References

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