“…Sedimentologists did recognize that grain shape might be more important than grain size in inferring transport processes (Dutta et al., 1993; Folk, 1980; Krumbein, 1941b; Pettijohn et al., 1972), and numerous seminal experimental works have been performed to explore grain shape changes in various abrasion environments (Kuenen, 1955, 1956, 1959, 1960; Krumbein, 1941a). More importantly, factors such as eolian sorting and abrasion, fluvial action, and chemical weathering controlling grain shape have also been qualitatively or semiquantitatively explored in natural and experimental conditions (Asumadu et al., 1988; Bui et al., 1989; Crook, 1968; Folk, 1978; Goudie & Watson, 1981; Khalaf & Gharib, 1985; Mazzullo & Ehrlich, 1983; Mazzullo et al., 1986; Pye & Mazzullo, 1994). However, the imprecise way to measure grain shape based on the descriptive Powers roundness grades (Powers, 1953) has large uncertainties and quite low reproductivity, limiting the broad applications of grain shape.…”