Abstract
The flat plane at the top of Udo hill in the southeast of Shizuoka city is called “Nihon-daira”. Its topographic significance and the history of its developement are discussed with reference to the geologic structure. The planes of sedimentation in four stages are recognized as follows:
Pleistocene _??_Kunozan plane (mostly destroyed by erosion)
Nihondaira plane
Kuniyoshida plane
Recent Alluvial plain
These planes have been repeatedly elevated by the unceasing doming-movement since the early Pleistocene age. In consequence, the hill is isolated from the mountainous hinterland by the alluvial plain.
In the writer's opinion these Pleistocene planes are the ancient surfaces of delta-like fans which were formed in the inter-glacial stages. This means that their intervals were the glacial stages when the sea-level was lowered.
It would be the best explanation for the topography of this area that it was figured not only by the doming movement but also by the glacial eustasy. In addition, there was an active agency which was the powerful transgression of rapid streams from the hinter mountains.
