Depositional environments of sandy sediments of the Ishikari coastal plain.

Abstract

The Ishikari plain is a typical coastal plain which is divided into four major geomorphic units. The purpose of this investigation is to clarify the differences of the four units in terms of depositional environments and to distinguish grain-size distributions of sandy deposits. 66 samples were analysed using grain-size parameters and Q-mode factor analysis. It is determined that depositional environments at a given locality in the Ishikari coastal plain are deeply influenced by the strong westerly winds and strong wave actions. It can be concluded that the Shakotan and the Takashima peninsulas which are located to the west of the Ishikari coast play an important role on the Ishikari coast, because they block the strong westerly wind.-English summary