Red-Burnt Clay and Early Chinese Architectural Technology: Archaeological Significance and Scientific Approaches to Firing Temperature Reconstruction

Abstract

Red-burnt clay remains (hongshaotu) are clayey architectural and occupation deposits that were reddened, hardened, and mineralogically altered by intentional firing or incidental heating. These materials document the transition from unfired earth-and-timber construction to fired ceramic architecture in Neolithic and early Bronze Age China, yet their archaeological value has been limited by reliance on macroscopic description for temperature reconstruction. This narrative review examines published cases — including Guanmiaoshan red-burnt house remains (~600 °C), Lingjiatan red ceramic blocks (>950 °C), Sujiacun burnt soil deposits (~500–600 °C), and Qiaocun composite roof tiles — and compares archaeometric methods for estimating firing temperature, heating temperature, and thermal history. The methods reviewed include magnetic susceptibility and thermal demagnetization, colorimetry, X-ray diffraction, petrography, Fourier-transform infrared spectroscopy, differential thermal analysis, thermal expansion, and physical property testing. Each method responds to different parts of the heating process and operates within a limited temperature range; no single technique covers the full spectrum from low-temperature occupation deposits to high-fired ceramic building materials. The review proposes a multi-method workflow that begins with field screening and contextual classification, matches analytical methods to the likely temperature range, and returns temperature evidence to questions of building practice, site formation, production organization, and the diffusion of firing techniques. Future work should build regional calibration databases from local raw materials, standardize the reporting of temperature estimates, and connect thermal data with architectural and technological history.