The Izumi Group developed in the western part of the Asan Mountain Range is composed of normal marine deposits (Kaino Mud Stone) and turbidity deposits (Takikubo Alternation of Sand and Mud). In this study, the authors tried to distinguished those two deposits by finding the orientation of the longest axis of the imbricated gravels and sands in the sandstone. In a consequence of the measurements, the boundary of those strata become clearly, and the debris which made up the Kaino Mud Stone, normal marine deposits, were mainly from the NNW region. Likewise debris forming the Takikubo Alternation were brought from the east of the area by the turbidity currents.