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Volume 77, Issue 1
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Nobuyuki YONEKURA1968 Volume 77 Issue 1 Pages 1-23
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe Kii peninsula, located on the Pacific coast of central Honshu, is fringed with coastal terraces in its southern part, while its east and west coast are characterized by ria shorelines. The purposes of this paper are to clarify coastal development of the peninsula, especially the history of vertical changes in sea level in its coastal region, and secondly, to examine the relation between the mode of Quaternary crustal movement (especially its vertical component) and recent crustal movement associated with contemporary seismic activity.
Coastal terraces and an interpretation of their development
Coastal terraces, developing along the southern coast of the Kii peninsula (Fig. 2), are mostly rocky abraded terraces covered with thin marine beds. In the northern part of the east coast (north of Shingu) and at the mouths of some rivers, however, some marine terraces are composed of marine sediments overlying fluvial beds. The coastal terraces are classified into two levels of the high and low terraces in the surroundings of Shingu, where they are typically developing (Fig. 4). Both levels of the terraces are further subdivided into some sublevels which are dentoted by H1, H2, H3 and H4 in the high terraces and L1, L2 and L3 in the low terraces respectively in the descending order. The height of each sublevels at Shingu are 125, 113, 95, 61, 49 and 39 meters above sea level. The highest terraces H1 are dissected into narrow hill ridges, overlaid by round gravel beds more than 20 meters thick. The H2, H3 and H4 terraces are rocky abraded ones. The most extensively developing terraces Li are composed of marine sediments underlaid by fluvial beds more than 40 meters in thickness. The L2 and L3 terraces are marine or fluvial terraces which have been formed cutting down the L1 terraces. Alluvial plains (denoted by A) do not so extensively develop along the coast, except at the mouths of the rivers. Judging from some boring data, alluvial formations at the mouths of the rivers are more than 30 meters thick (Fig. 3). From these facts it is concluded that the Hi and Li terraces and alluvial plains are depositional surfaces composed of thick marine and fluvial deposits, which are filling submerged fluvial valleys and, therefore, that the coastal region, being interrupted by temporary submergence, has been emerged in precess of the formation of the coastal terraces. The other terraces H2, H3, H4, L2 and L3 have no feature indicating submergence and, therefore, are considered to have been formed in process of emergence. Judging from the thickness of deposits, amplitude of submergence during the later two periods is considered to be greater than that during the previous period.
As to the process of formation of alluvial plains, rapid submergence of this period is regarded in another regions as being largely due to eustatic rise in sea level caused by world deglaciation from the results of the researches on submerged topography, marine topography, succession of alluvial formations, absolute age determination of alluvial marine beds, climatic changes and etc. The process of formation of alluvial plains in the Kii peninsula is inferred to be the same as in another regions from the submerged fluvial valleys and the thickness of alluvial formation and, therefore, the submergence during the last period was caused by eustatic rise in sea level.View full abstractDownload PDF (3117K) -
Hiroshi MASUMURA1968 Volume 77 Issue 1 Pages 24-36
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe survey of the almost entire islands of Japan carried out by Tadataka INO (1748-1818) was a remarkable and successful enterprise in the history of Japanese cartography, and many biographies and biographical stories of INO have been published. However, among them “Tadataka INO” written in 1913 by Prof. Ryokichi OTANI (1875-1934) was the only one in respect to the scientific, authoritative and substantial point of view.
Prof. OTANI, as a physicist and geodesist, naturally devoted nearly two-thirds of his pages to the description of INO's method, instruments, the adjustment of his surveys and his method of map-construction, the accuracy of maps, etc. On the contrary, the description about his travels of survey is treated rather briefly and subjectively and, in consequence, there remain some criticism in his description from the strict historical point of view. For instance, OTANI pointed out some instances of scandals which occurred between lords of clans and INO's party in the survey of Echigo and Kaga, while he emphasised the friendly help of the feudal lord of Kagoshima, contrary to the expectation of some difficulty and hindrance in such a powerful clan.
The author analyzed these circumstances from many old documents and presented proper interpretation and also revealed that the INO's party changed its character and increased its importance after INO was appointed as an official of the Tokugawa Government in 1804.View full abstractDownload PDF (2401K) -
Ken'ichiro TAKENAGA1968 Volume 77 Issue 1 Pages 37-55
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe purpose of this paper is to classify low-altitude erosional surfaces in Japan and also to investigate the characteristic features of the granite mountains.
Mt. Suzugamine at the western part of Hiroshima city is consisting only of granite. The geomorphic surfaces of Mt. Suzugamine are classified roughly into two, Higher-Setouchi surfaces and Lower-Setouchi surfaces. Yamada surface of the Plio-Pleistocene in origin and Piedmonttreppen belong to the former and gentle slope remnants of early-middle Pleistocene and “Kannon surface” of middle-late Pleistocene belong to the latter. Neither marine terraces nor tephra are found in this area. As a result, it is difficult to correlate these with the geomorphological surfaces elsewhere which have already been well examined.
The gentle slopes were formed by the removal of deeply weathered granitic top soils about 50 m in thickness and the climatic change seemed to be less active.
Landforms were modified even in Würm glacial period as was seen in the “Kannon surface”. The agencies which formed the initial gentle slope is similar to one which formed “Kannon surface”.
Suzugamine mountains, which consists of granite, is characterized by gentle slope, box valley, earth fall, block stream, wide-opening valley and inward-opening valley. I should like to propose to term such geomorphology “granite topography”. It may be seemed that downwarping movement toward the Inland Sea (Setonaikai) has lasted down to the Pleistocene period, on the ground that the upper streams running down northward were captured by the ones running down southward.View full abstractDownload PDF (3595K) -
[in Japanese]1968 Volume 77 Issue 1 Pages 56-58
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
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[in Japanese]1968 Volume 77 Issue 1 Pages 59
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSDownload PDF (186K) -
[in Japanese]1968 Volume 77 Issue 1 Pages Plate1-Plate2
Published: February 25, 1968
Released on J-STAGE: November 12, 2009
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