Construction Systems of Neolithic Dolmen Walls on the Iberian Peninsula

Walls of corridors and chambers in the Neolithic dolmens of Portugal and Spain were constructed using megalithic slabs or masonry. When constructed with slabs, the slabs were arranged using two very different construction systems, based either on placement of an orthostat or on imbrication of the slabs. Although generally dolmens are described with orthostats, on the Iberian Peninsula are most often constructed using imbricated slabs. The walls of orthostatic and masonry dolmens are lintelled structures. The walls of imbricated slab dolmens, however, are unique structures without later representation. Temporally, the orthostatic dolmens represent the earliest construction system, followed by those of imbricated slabs and finally those of masonry. This evolution can be explained in terms of the capacities of the selfsupporting walls and simplification of the construction processes.