粒度組成に基づく土器胎土の定量的分類 ―纏向遺跡出土土師器を例として― ; A Quantitative Classification of Fired Paste Based on the Grain Size Composition －In the Case of Potsherds from Makimuku Remains－

A quantitative classification of the fired paste was carried out，based on the grain size composition，with the object of finding indices for mutual discrimination among various kinds of paste．65 samples，from which 66 thin sections were analysed，are Hajiki potsherd e xcavated from Makimuku remains in Nara．These samples show the great variety of the time of production and of the origin presumed archaeologically. It is more practical to regard each sample as three component system of clay，silt and sand，than to subdivide the class of grain size in the coarser or sand part， taking account of the error and their rates which are incidental at the time of point－counting. And that suffices to characterize various kinds of paste． As a result of analysing each sample of three component system，four kinds of paste were discriminated. They are as follows：the paste of levigated clay（L），the one of high purity clay（H），the one of sandy clay（S），and the one of tempered clay（T）． As the index for mutual discrimination，Sand％ has the effbctiveness considerably． On the discrimination between L and H，levigation index（＝ln（clay％／sand％））is preferable to sand％．On the case between T and S，tempering index（＝ln（sand％／silt％））may be so．