Since an Encrinurus had been described from the Southern Kitakami mountains by Sugiyama in 1941, additional occurrences of Silurian trilobites were reported from Gionyama of Kyushu, Mt. Yokokura of Shikoku, Hitoegane of the Hida plateau and other places and Kobayashi and Hamada have published a monograph on Silurian Trilobites of Japan in 1974. Recently additional trilobites amplified the Japanese fauna besides Silurian cephalopods from Mt. Yokokura. All of these fossils are in a range from Wenlockian to Ludlovian, if not from middle Wenlockian to middle Ludlovian. Encrinurus and other fossils reveal affinities to the fauna of the Mongolian geosyncline on one side and to eastern Australian one on the other. The Silurian cephalopods indicate the faunal connection from Japan to Bohemia through South China and Turkestan.
This paper describes the effects of the drainage basin characteristics on river runoff and chemistry of river water. The drainage basin characteristics influence the amount of water yield and chemistry of river water. The drainage basin characteristics are composed of topographic condition, rock and sediment type, vegetation and land use. Most variable characteristic of Iceland is permeability of rock. Iceland is on the Mid-Aelantic Ridge and active volcanic zones run across the island. The Tertialy strata which are almost impermeable are exposed at northern west and east coast of Iceland. Icelandic rivers are divided into three groups by the pattern of runoff variation and chemical conditions. “Spring-fed rivers” : The amount of runoff and chemical conditions are very even all year round and unaffected by the amount of rainfall. This type rivers are mainly founded in the central zone that is highest permeable area. “Direct runoff rivers” : The variations of runoff and chemical conditions are very much dependent on the variation of rainfall. These variations are very anomalous. This type rivers are found in the areas of the impermeable basaltic rocks. “Glacier rivers” : The amount of runoff varies annually. The amount of runoff is very large in summer and is very little in winter. The most typical characteristic of this type rivers is the high concentration of suspended sediment.
The purpose of this study is to clarify bases of development of viable dairy farming system through an intensive fieldwork by synthesizing many farming elements : farm household, management, dairy cattle, land use, settlement pattern, landownership, and dairy facilities and equipment. The study area is Oyaharakaitakuchi, Naganohara Town, Gunma Prefecture, which is located at the northern foot of Mt. Asama, 150km northwest of Tokyo, and is a part of the volcanic slopes in northern Kanto District. With few opportunities of non-agricultural employment, the study area is characterized by specialization in highly productive commercial farmings : vegetable growing and dairy farming, according to land conditions. Viable dairy farming in this area has developed since the early 1960's and the viable dairy farms account for about 70 percent of the total farms in the area, showing higher concentration than in other areas. The viable dairy farmers in the study area have increased family members engaged in agriculture, enlarged area of forage crops, introduced large-scale dairy facilities and equipment, and kept large dairy herds with large-scale arable land. The most specialized group of dairy farms keep 45 dairy cows on an average and attach much importance to save expenditure and to improve milk quality in keeping dairy cattle. Milking cows account for only 70 percent on an average of the total dairy cattle kept by viable dairy farms, and the rest are calves and heifers for renewal of milking cows. Though percentage of the total milking cows in much delivered cows is only 10 percent, advanced registration cows account for about 80 percent. Development and cosolidation of arable land have been promoted with the advancement of keeping large dairy herds. Arable land has been enlarged by land reclamation and conversion of forestland to arable land, because potential land to be reclamated was more easily available than in suburban and outer suburban zones in the Tokyo metropolitan area. In the course of land development, there have been changes in landscape in terms of spatial patterns of settlement, roads, landownership and land use : for example, scattered and isolated land plots have been consolidated so that each farm may own fewer number of larger land plots near the farm household and may simplify land use pattern. The viable dairy farms in the study area are relatively highly dependent on self-supplied feed, although those in other areas more or less depend on purchased feed. The viable dairy farms in the study area use arable land predominantly for forage crops to produce self-supplied feed, which accounts for about 60 percent on an average of the total feed requirement, and the percentage of the total self-supplied feed in silage feed is about 80 percent. Therefore, ratio of the feeding cost to the value of sold milk is only about 40 percent. But ratio of the net income to the gross income still remains to be about 30 percent because loan repayment for dairy facilities and equipment is higher than in other areas. As a conclusion the development of viable dairy farming with large dairy herds in the study area has been mainly supported by availability of sufficient labor force and arable land, reflecting the geographical features of the area.
The Hohi Area (130°50'431°35' E, 33°00'33°30' N) has been intensely surveyed for geothermal resources by the joint team under the auspices of the NEDO. Geologically, the Area is mainly composed of Neogene volcanics, with subordinate local lacustrine sediments. The ages of the volcanics were measured by the K-Ar method as well as the fission track method, the most of the latter leaving some problems in connection with statistics. The ages by both methods of thermally altered volcanics are problematic. The reliable 114 K-Ar ages of unaltered rocks, which cover the range of 0.32±0.055.3±0.3 (106y), are divided into six stages according to volcanic activity. They are the Recent Volcano, Shibayakata, Kusu, Nakatsue, Yabakei, and Usa stages. The character of each stage is described and the distribution of the stratigraphic units are figured in a geological map as Fig. 3. The Yabakei Welded Tuff (W in Fig. 3) is a characteristic unit covering the plateau of 300km2 in area. The Welded Tuff occurs with intimate association with pumice deposits and rhyolite lava beds, all of them being 0.91.3 (106y) in age. This acidic volcanic group, named Hidjudai Acidic Complex ', appears to be a divider of later and earlier series of the Hohi volcanics. Before the Hidjudai complex erupted, the volcanic activity of the Area had been rather extinct in early Kusu stage, and local in the Nakatsue stage. Consequently the complex covers the Yabakei and Usa series unconformably. In succession to the Complex, the vollcanic activity became very intense in the central part of the Hohi Area in the Shibayakata stage, and then became less active in the Recent Volcano stage.
The paper presented distribution maps of climatic water balance components in the southwestern part of Japan. The water balance was evaluated by means of bookkeeping procedures based on the Thornthwaite's system (1948). According to the concept of Russell's climatic years (1934), potential evapotranspiration, water surplus, water deficit and number of dry months were annually evaluated and averaged for a period of sixteen years from 1967 to 1982. The distribution maps of the four components were made by using the mean annual values at 415 stations. The maps show precise regional differences among plains and basins and provide basic data, for example, for the studies of vegetation and land use.
Two fine vitric tephra layers of middle Holocene age are recognized in peaty surface soil on Mt. Tide. The lower one is identified as the Kikai-Akahoya ash (K-Ah, about 6, 300y.B.P.) on the basis of type, refractive index, and major element chemical composition of volcanic glass shards and 14C age. The upper one is called the Azuma ash (Az) and has some similarities to Towada-Chuseri ash (To-Cu, about 5, 400y.B.P.), although further inspection is necessary. Az can be seen at many localities on the Tide and Asahi Mountains. These tephras, especially Az, would be useful in chronological study of slope formation in these areas.