Site formation processes at Zhoukoudian, China

Zhoukoudian is often cited for its human remains and the early evidence of fire. Yet, since its first excavations over 70 years ago, detailed studies of processes responsible for the accumulation of anthropogenic and geogenic sediments in the site have been sparse. This paper provides some details of site formation processes mainly through field observations of the extant section at Locality 1, and the use of soil micromorphology and Fourier Transform Infrared Spectrometry (FTIR) analyses of the sediments. Samples from Layers 10 through 3 show extensive water deposition of fine silt-sized material (reworked loess), including fine-grained organic matter. The dark organic-rich unit in Layer 10--often cited as one of the earliest evidence of fire--is a water-laid accumulation. Much of the fine-grained sediment was derived from outside Locality 1, implying that the site was open to varying extents throughout most of its depositional history. The 4-6 m accumulation of "ashes" in Layer 4 represents subaerial water-laid silt deposits derived from the loess-covered hillslopes surrounding the site. They presumably accumulated in an open depression that formed after the collapse of the brecciated roof deposits represented by Layer 6. Diagenesis is present in many of the Layers, and is exemplified by calcite precipitation and dissolution, and localized apatite (dahllite) replacement of calcite. In Layer 4 diagenesis is more advanced, including calcite/dahllite precipitation, subaerial weathering of the loess and associated precipitation of hematite, alteration of clay and the neoformation of quartz. Many of our conclusions concur with those of Teilhard de Chardin & Young published over 70 years ago.