旧石器时代石制品热处理研究:回顾与展望

Fire and Stone:An Overview of Paleolithic Heat Treatment of Stone Artifacts

热处理技术作为旧石器时代古人类提高石器制作工艺水平的代表性技能,一直以来倍受国际学术界的重视,在已经开展的40余年工作中积累了丰硕的研究成果。由于我国旧石器时代石料的特点及热处理研究的某些技术手段本身存在局限性,尚未在考古遗址中发现热处理行为及相关遗物,目前我国热处理研究仍处于空白阶段。本文主要介绍旧石器时代热处理技术的原理与工艺及相关研究手段,特别是针对热处理技术的实验研究。相信随着认识的加深,石制品热处理研究会在我国旧石器考古学研究中发挥重要作用。

The earliest evidence for heat treatment of stone materials has been found in South Africa having appeared as early as 164ka and predominates among silcrete tools dated to 72ka years ago from Still Bay, South Africa. Use and control of fire are important behaviors for human evolution as deliberately heating materials improve the rock＇s physical properties. Archaeologists have conducted experiments to investigate heat treatment since Shippe （1963） regarded this activity as an important research aspect in prehistoric archaeology. What and how physical properties of material changed by heat treatment are the two issues of this research. The following observations are noted. 1） Some changes are visible by the naked eye such as changes in color, a greasy lustre on heated siliceous rocks; heat damage; and a slowness or acceleration of development of a patina. 2） Macrostrul changes accompanying heat treatment include： fracture toughness is reduced with increased temperature; elasticity increases with increasing temperature; loss of light energy by thermoluminescence; obliteration of fission tracks; and loss of water of hydration. 3） Microstructural changes accompanying heat treatment can be detected by X-ray diffraction, infrared absorption spectroscopy and with scanning electron microscopy. The following characteristics of heat-treated rock are： disintegration, pot-lid fractures, flake splitting, transverse fractures, and surface crazing. In addition, heated raw material could yield more flakes with less force, and with the flakes being longer than the ones from unheated raterials. It is important to recognize that these characteristics are not consistently apparent in heat-treated materials. Due to the raw materials constraints, no heat-treatment stone artifacts have been identified so far in China. Since heat treatment is considered as an important part of modem human behavior, we suggest that Chinese archaeologists should pay close attention to the identification of heated artifacts and more efforts should be emphasized in experimental work.