How was the Suruga Bay formed?

Abstract

 This paper described how the Suruga Bay was formed based on the geology around and in the Suruga Bay. The gravel bed of the Negoya Formation was distributed on the summit of the Senoumi-Kita Bank in the Suruga Bay, and the gravels were supplied from the Abe River. It became clear from this that the Senoumi Basin relatively has subsided 900 m to the Senoumi-Kita Bank and the Udo Hill since the Negoya Formation beginning to deposit. Besides, there is erosional unconformity surface on the continental slope of Izu Peninsula, which was land during between the late Pliocene and the early Pleistocene. And Izu Peninsula upheaved in the time which the Negoya Formation deposited. From these things, the Senoumi Bank and the both side lands of the Suruga Bay have upheaved since about 400 thousand years before, and the sea level has risen gradually about 1,000 m simultaneously. As a result, the Senoumi Basin submerged and the Senoumi Bank was isolated. That is, the Suruga Bay was formed by the large upheaval movement of island arcs and the sea level rise about 1,000 m which took place since about 400 thousand years before.