大潟海岸における海岸変形の特性について(3) ―カスプと底質の特性―

Abstract

During the past few years a series of investigations has been conducted to find geomorphologicand sedimentological characteristics of Ogata coast facing Japan Sea. The beach conllgulationalong the coast from Naoetsu to Kashiwazaki, with special reference to rhythmic shoreline, andthe textural study of related beach sediments are discussed in this paper.Shoreline landform characterized by rhythmic shoreline reflects rhythmic configulation ofsurf zone bed. The detailed study concerning the cusps indicates that cusps vary in mean wavelength from 100 m-300 m in the western part to 300 m-500 m in the eastern part of the coast.Spectral analysis of shoreline configulation shows same tendency.Textural parameters of beach samples reveal that a larger part of the area is floored by well-sorted, coarse materials ranging from gravels to sands in size. Coarse gravel sediments are con-fined to the central part with few exceptions in the western part of the beach. Fine materials occuron the eastern and western side of the beach. Beach sediments change gradually in ssze com-position in the longahore direction. There appears to be a general inter-relationships between thelongshore variation of beach configulation and the textural parameters of the sediments.