Study of Reduction Intensity on the Side-Scrapers of Komishan Cave, Mazandaran

One of the ways in which life-histories of formal stone tools could be studied is taking advantage of analyses of diverse retouched edge types، patterns of the retouch، its relative continuity and intensity، and mass/volume loss during retouching process. Study of retouch could provide new insights into the reconstruction of subsistence strategies of ancient societies، intensity of activities، technological organization and so forth. Several episodes of edge retouching processes (for making tools، rejuvenating its edges، resharpening، etc) gradually reduce the basic volume/mass of blanks and tools. Therefore، gradual and progressive decline in stone tool’s volume/mass is the fundamental element of the reduction thesis. Reduction thesis states that lithic’s size and shape will change -due to the human activities- from acquisition of raw materials to discard، and this continuous transformation is always in the form of stone tool’s weight/mass loss. In this research، the main focus is on the concept of reduction/retouch intensity on unifacially retouched tools (URTs) recovered from Komishān cave، a prehistoric site located at the southeastern shore of the Caspian Sea. This site is a karstic cave in the northern foothills of the Huto-kash Mountains، a subset of Alborz Mountains. Lithic assemblages of the cave suggest a broad spectrum of activities were performed by its prehistoric inhabitants. Almost 10 types of tools identified among the stone artifacts. The URTs recovered from 2009 excavation of the cave are subjects of this study. These URTs belong to both disturbed and in situ layers. Totally، they add up to 43 pieces in which، 1-30 belong to the disturbed layers and 31-43 associated with in situ (and lower) layers. The most obvious characteristic of Komishān cave assemblages is the abundance of backed pieces with considerable proportion (pieces with retouched edge angles higher than 70° constitute %25. 6 of the assemblage. This kind of steep edge is generally called backed edges). Stone artifacts of Komishān generally made on large blanks، suggesting a local accessibility to high quality raw materials. In addition to that، absence of any kinds of uniformity or standardization among the URT assemblage might indicate easy access to the high quality raw materials. In this research، at first، the reduction/retouch intensity of the URTs was calculated، and then tried to relate this relative intensity to probable site function and use during the Mesolithic Age. The method used here is based on geometric and mathematical calculations، and in this regard، authors took advantage of the three geometric reduction indices that are IR، II and ERP. The IR، II، and ERP values probably indicate the variable nature of reduction، so it seems these three indices are complementary to each other، and using the tri-index approach in which each of these indices is getting involved، one can understand about relative reduction/retouch intensity of individual stone tools or lithic assemblages in a given prehistoric site. In sum، the results indicate that reduction/retouch intensity of Komishān’s URTs is almost moderate، and significant volume loss along the URT’s lateral edges is probably an outcome of uncontrolled percussion retouching and not due to the continuous story of dulling and resharpening. Considering the fact that inhabitants of Komishān cave had access to the high quality raw materials، such reduction strategy might be expected. There are some evidences that suggest Komishān cave was most likely a base camp with long-term occupation at the periphery of the site (low mobility). Among these are the evenness index، the specific ecoregion of the southern shore of the Caspian Sea (rich ecoregion)، faunal remains، and reduction/retouch values.