Building on an oasis in Garamantian times: geoarchaeological investigation on mud architectural elements from the excavation of Fewet (Central Sahara, SW Libya)

The paper describes the micromorphological and mineralogical properties of earthen architectural elements from the excavation of the Garamantian compound of Fewet (Central Sahara, SW Libya), settled between the 2nd century BC and the 1st century AD, and compares this evidence with a set of samples from historical to modern context of Saharan and Sub-Saharan Africa. At Fewet, the production of mud bricks, plasters, and mortars employed in the building of the compound required raw materials available near the settlement. The earthen elements lack almost completely clay and organic temper, and their main components are quartz grains (sandy to silty) and a calcareous and slightly organic mud, available beside former springs. Only plaster and mortars show the addition (in limited quantity) of finely subdivided vegetal remains to the mixture. The technology for earthen elements used in Garamantian times resembles those today applied at many localities in Sub-Saharan Africa. Finally, our analyses showed that in the last millennia archaeological sediments underwent limited postdepositional weathering, mostly related to solute redistribution after occasional rainfalls. Today, the same process affects traditional mud brick buildings.