HISTORICO-GEOGRAPHICAL RESEARCH ON THE JORI-SYSTEM IN THE BASINS OF TAMBA AND ECHIZEN PROVINCES

Abstract

In Japan, up to now, historical geographers have usually tried to be restored the geographical landscape and the other historical aspects with every time of the past to the original state by using ancient documents, ancient maps, and cadastral maps. And then the geographically restored landscapes at every time have been projected one after another on a map which is used in the present time. This is known in terms of “successive cross-section method”. The long and the short of it is that the geographical land features (natural aspects) had been of little importance in their investigations. So, on the contrary, the author has been made a full discussion of the above-mentioned subject from a stand-point of the natural changes of micro-landform which is inseparably bound up with the process of land occupation by man in the historical age. The Fukuchiyama-Ayabe, Kaibara, Sasayama basins surrounded by mountains on all sides but one, and the Ohno and Katsuyama basins situated in the Ohuetsu mountain regions were selected as basins for the research and investigation. Taken altogether it has been definitely shown by the following three works that, land development considered, our research and investigation goes a long way toward a better under-standing of the manor structure in the mountain basins: that is, (A) to group the land sur-face of their basins under several landform types, (B) to search after the earth mark allotted according to the grid pattern of Jon-system in the Nara a era that underlie the history of land development in the basins, (C) to clear up the relation between the allotment of grounds and the landform. The results obtained are as follows: 1) As a rule, the land surfaces in basin are formed from about thirteen varieties of diluvial upland, alluvial fan, river terrace, valley plain, flood plain, natural levee, and the like. However, we are able to classify them into two groups; one is basin formed from depositional phases as the main constituents and the other is basin come into being from erosional phases along the river courses which have worn channels through the soft depositional phases. 2) In the Kaibara basin, depositional phases are observed and on the land surface we could not be recognized the existence of the erosional phases. On the other hand, in the Ohno basin, the erosional phases are gradually forming on the landsurface of depositional phases. Among the river terraces, in the Sasayama basin, flood plains have well-developed out of the landform which does not show as yet the erosional phase. And in the Fukuchiyama-Ayabe basin, the natural levees have highly grown among the river terraces. 3) A difference of micro-landform has brought diversity on the distribution of allotment of land performed according to the grid pattern of Jon-system, namely, in a case of the Kaibara basin the earth marks of land allotted in accordance with the Jon-system are found out on the flood plains of depositional phase. In the area formed from the braided rivers, we can not recognized the earth mark. In witness where of the braided rivers, it did not develop into a clear formation of erosional phase there. Ohno basin where the growth of depositional phase is conspicuous is a far cry from the Kaibara. On the left-over areas (back swamp) where were no filled up by a river, the earth marks allotted according to the grid pattern of Jon-system in the Nara era have observed distinctly. However, there is no allotment of land on the dormant alluvial fans. In the Sasayama and Katsuyam.a basins, on the other hand, they spread out neatly on the land surface of river terraces. On the contrary, in the Fukuchiyama basin the allotments of land performed in accordance with the Jon-system locate on the flood plains among river terraces.