1960 年 1 巻 7 号 p. 243-255
The Sagami group, the lower Pleistocene deposit, distributes into the South Yokohama Hills, Sagamino Upland, and Oiso Hills in the southern Kanto region. The stratigraphy and sedimentation of the group in those aeas have been re-examined, and it has been known that the development of the Sagami sedimentary basin has the following three stages.
1. After folding in the Miura group, the initial subsidence of the Sagami sedimentary basin began, and a part of the rugged land surface was covered by a rush marine transgression. Thus the Naganuma and Ninomiya formations deposited.
2. Thereafter the basin spread with the progress of the basin-forming movement, while the regressive facies remained there, and volcanism began to the western district. The estuarine Byõbugaura and lacustrine Tsuchizaw a formations deposited overlapping the Naganuma and Ninomiya formations respectively.
3. Towards the end of the deposition of the Byõbugaura-Tsuchizawa formations a large quantity of volcanic ashes and lapilli (Tama Loam member) was supplied and the tectonic movement occurred in the Oiso Hills. In the meantime the Sagami sedimentary basin emerged in the whole area and the basin became extinct.