津軽屏風山砂丘の地形
1968 年 20 巻 1 号 p. 34-42
詳細
1968 年 20 巻 1 号 p. 34-42
The results of the author's study on the Byobusan sand dune area along the Japan Sea to the west of Tsugaru plain are as follows ;
(1) According to grain-size analysis the sand in this area is classified into four groups ; recent dune sand (A type : Mdφ= 1.51-1.76Q, dφ=0.26-0.33), older dune sand (B type : Mdφ=0.68, Qdφ=0.48), sand derived from the Byobusan formation underyling the sand dunes (C type : Mdφ=1.48, Qdφ=0.66), and beach sand (D type : Mdφ=1.12, Qdφ=0.64) (Fig. 2, Table 1). The Byobusan formation is correlated to the Shimosue-yoshi stage.
(2) Three levels of terraces are recognized in this area; 10 m terrace, 20 m terrace and 30-40m terrace, the figures indicate their heights above the sea-level (Fig. 5). These three levels have been formed by eustatic sea level change since the Shimosueyoshi stage (Riss-Wurm interglacial stage).
(3) The pattern of the sand dunes is characterized mainly by longitudinal dunes and parabolic or U-shaped dunes (Fig. 7·8). The recent sand dunes cover the older sand dunes and volcanic ash layer on them.
