Abstract: Similar to handaxes and cleavers, knives made on larger flakes and found in the Luonan Basin, Shaanxi Province, China, challenge many preconceived ideas about the distribution of Acheulian lithic remains. This article focuses on the definition of knives as expressed by Kleindienst[1 ]and Clark & Kleindienst[2 —3 ]. According to these authors, the knife should be a kind of tool having the whole or part of one edge blunted by retouch or naturally backed, with the opposite or cutting edge showing bifacial, unifacial or no retouch. Based on the strict definition that a knife should be made from a larger flake, or should be a kind of retouched flake tool, 24 knives made from larger flakes were identified from 19 open2air sites (or localities) in the Luonan Basin, central China. This work is the first time that knives have been identified in China. The 19 open-air sites that had knives are among 268 open2air sites surveyed between 1995-2004 in the basin.
This article describes knife raw material and provides metrical analysis of this tool type. Early hominids in the Luonan Basin chose four kinds of raw materials with the most common being cream quartzite. Metrical analysis indicates a mean length of 174.17mm, an average width of 118.80mm and a mean thickness of 50.09mm. The mean weight of the knives studied was 1135.33g. Various indices as measured by the following ratios were : (widthΠlength) ×100 equals 72.22 ; (thicknessΠlength) ×100 equals 30.02 ; (thicknessΠwidth) ×100 equals 43.21.
The open2air sites in the Luonan Basin were not subject to secondary sedimentation. At these sites, lithic artefacts were discarded by early hominids and incorporated into undisturbed natural loess deposits. Artefacts were contained in the loess deposits, and recovered due to loess extraction for brick manufacture. On the higher terraces, lithic artefacts were exposed on the surface of the higher terraces because of long-term land surface erosional processes. Loess stratigraphy of the second terrace belongs to the Lishi Loess, formed in the middle to late Middle Pleistocene (Q2 2 - 3 ) . The TL dates indicates the chronological date of the second terrace is over 250 ka BP. New preliminary OSL chronological dates shows that the loess deposits on the third and fourth terraces are about 90—50kaBP, and this evidence suggests that the loess deposits on these higher terraces formed in the Late Pleistocene.

Key words: Knives; Definition; Open-air sitesΠlocalities; Luonan Basin; Shaanxi province ; China