Decoding a Basal Date Palm Trunk Interface in Vernacular Hybrid Walls: Evidence from the Ziban Oasis, Algerian Sahara

At the same base of some vernacular walls in Algeria’s Ziban oases, date palm trunks form a recurrent transition between a stone plinth and an earthen body. Although previously reported, this junction has not been systematically characterized across architectural settings and construction variants. This study combines non-invasive field documentation, stratigraphic and comparative analysis at building, wall and interfaces scales. The configuration was confirmed in 10 of 15 surveyed settlements. Within the documented load-bearing walls, the palm course is seated between bedding mortar layers and occupies the wall depth through transverse, longitudinal or mixed arrangements. Variations in trunk form, course number and adjoining masonry define different implementations of a shared construction principle. At documented corners, timber elements meet without visible interlocking, ground-entrances interrupt the palm course. Preservation differences distinguish surviving contact conditions. The findings establish the assembled basal junction as the central unit for interpreting this configuration. They provide an architectural basis for questions concerning mechanical behavior and moisture transfer, whose specific effects remain to be established.