The artificial dwelling floor design in the late Neolithic Age: A comprehensive study of the Shuanghuaishu site, China

The Shuanghuaishu site was the highest central settlement with the nature of a capital city found so far in the early stage of the formation of Chinese civilization in the Yellow River basin. It had yielded a wealth of Neolithic building relics, like encircling trenches, earth houses, sacrificial altars, and courtyards. For a long time, the floors of prehistoric artificial dwellings had served as a critical material for researchers to investigate prehistoric activities and delved into the structures and materials of building practices. Thus, in this study, a comprehensive analysis method that combined morphological, compositional, and physical property detection was employed to investigate the seven house floors from the late Neolithic period at Shuanghuaishu site (3500–3000 BCE). The results revealed three distinct types of floor structures: single-layer, double-layer, and multi-layer floors: the single-layer floors constructed from ginger nut (a quaternary deposit abundant in calcium carbonate) powder or fire-baked earth was commonly used as artificial dwelling floors during the late Neolithic age in China. The other two types mostly included untreated soil in the bottom layer as a cushion layer and a blend of ginger nut, river sand, and soil in the upper layers. Simulation experiments demonstrated that this floor design enhanced the floor’s strength and durability without compromising its moisture resistance. Notably, we discovered rare gypsum plastered floor layers in three cases, marking the first identification of such artificial structures in Neolithic China. Additionally, some floors showed needle fiber calcites deposited by biological factors on the surfaces, not from the lime plaster used.