The Musashino Upland, of which the uptown of Tokyo City is situated on the south-eastern part, can be classified into four series of terraces (fig. 1). Of the terraces the widest one is the so-called “Musashino Terrace” which is roughly shaped like a fan. But in detail, the longitudinal profiles (fig. 2) and the surface form shown by contours indicate that the Musashino Terrace has an abnormal shape as a fan. The author, therefore, compares the shape with that of the theoretically considered fan, and concludes that the north-eastern part of the Musashino Upland tilted up to the east.
In the Kanto district, there are two tectonic basins; one of them is in the central Kanto, and the other in the Tokyo Bay. The tilting of the Musashino Upland is in the central Kanto basin and the southern Musashino lies just midway between these two basins.