1) Establishment of landform division is the fundamental job for geographical science. Many attempts have been accomplished for the chorographic scale classification. To classify in topographic scale, several geographers have proposed to identify the basic landform unit. For example, D. L. Linton (1951) named the basic landform unit as “site”. The author also tried to systematize the classification and named the basic unit as “Landform type”. 2) We have to systematize from the basic unit to major Landform division, province and section which are previously used for the establishment of landform region. The author proposed the system from type, via series, association, section and province to division. 3) The major job of landform classification is to identify “Landform type”. The result of landform classification will be very useful not only for geography itself, but also for other sciences such as pedology, plant ecology, agronomy, forestry and so forth. We have applied the idea of landform classification to Landform classification survey (Fig. 1, Tab. 3), flood protection survey, land classification survey and so on.
The group in this area is divided, in descending order, into the following formations : Itoshiro subgroup …Saradani shale (about 50 m thick) Kuzuryu subgroup Kowashimizu sandstone (about 600 m thick) Sakaidera alternation of sandstone and shale (about 1, 000 m thick) Higashiamada conglomerate (about 150 m thick) The Higashiamada conglomerate overlying the basement granodiorite consists mainly of the subangular pebbles of granodiorite. Judging from the pebbles the sediments of the conglomerate may be originated from the granodiorite mass which is extensive in the upper reach of the Asuwa River. The Kowashimizu sandstone consisting of coarse-grained arkose was probably deposited in the shallow sea. In the middle Kuzuryu region which includes the Asuwa district the group forms a large synclinal structure. Its axis runs from the northwest to the southeast through Mt. Daibutsuji, while in the Asuwa district the group shows a monoclinal structure.This, however, constitutes the southern wing of the synclinal structure. It is considered that this folding of the group had been completed before the Tertiary formations were deposited.
M. O. BORSUK (1956) in his abstract (in Russian) on the Paleogene flora of Saghalin stated that the lower Due formation and the conglomerate bed contain many plant fossils, although the species are not much variable. The age of these fossils is defined as Late Eocene to Oligocene. These plantfossils from North Saghalin are illustrated in 21 figures. The difference in flora between the Upper Due formation and the Lower Due formation chiefly depends upon the climatic changes. The Agnevo formation is very similar to the Upper Due formation. The Agnevo formation was primarily defined by A. I. KRYSHTOFOVICH (1925). On the basis of the columnar section, the translator believes that this formation is not the upper part of the Khoinji volcanic effusives. According to the translator's experience in South Saghalin, the Agnevo formation may be correlated to the Kiyokawa coal-bearing formation. So, the translator wanted to make this relation clear by adding the geologic map compiled from previous data. The lower coal-bearing formation (Naibuchi group) may be correlated with the upper half of the Yubari group in Hokkaido and may be Oligocene in age.