Abstract
The author applied the granulometric and morphoscopic analysis to the samples of beach sand collected at 26 localities with intervals of about 2 km on the “estran” along the Rumoi coast. The results of these experiments, shown in figures 3 to 5, are summarized as follows:
Generally, the beach sands are concentrated in medium grades in composition of grain size, and the median diameters (Md∅) are 1.0 to 2.0 in ∅ scale, so the mean gradient on the estran retains a very gentle slope of 4 to 8 degrees. Unlike fluvial sands, they have a high sorting index (Pd∅) of 0.61 on the average. Judging from these facts, it seems that the distribution of beach sands is commonly controlled by the sieving action of breakers.
The roundness of beach sands is 0.36 on the average in medium size, tends to the intermediate grade between river and dune sands. At any rate, the classification of the four types of quartz grains based on the Cailleux's method, points out the marine origin of EL type more than 30% in contents, yet RM grains originated from dune and beach-dune ridge are simultaneously contained in the beach sands.
