On the Shore Type of the Tohoku District

Abstract

As the result of the consideration on the distribution of the shore type in the Tohoku District, the author recognized the followings.(1) In the Japan Sea coast, several parallel bars are developing for many miles along the shore. On the other hand, in the Pacific coast, either one significant bar is existing or bar is absent entirely. The shore without bar in the Pacific coast exist in the bay such as the Sendai bay and the northern coast of the Shimokita Peninsula.(2) The difference of the shore type between the Japan Sea coast and the Pacific coast occurs from the difference of the breaking type. In the Japan Sea coast, sea bottom gradients are smaller and initial wave steepness are greater than in the Pacific coast. So that in the Japan Sea coast, the tendency of spilling breaker is stronger than in the Pacific coast.(3) In the bar coast, the size of bar of the open shore is burger than that of the secret shore, On the other hand, in without bar coast also, the bottom profile of the open shore has the terrace 3 meters in depth.(4) The size of these bars is related to the gradient of the sea bottom shallower than 20 meters in depth.