STILLE'S conception of phases seems to be widely accepted in Japan as well as in Europe. There are, however, many different opinions about the intensities and durations of the bretonic, sudetic and asturic phases, the main phases of the Variscan (Hercynian) orogeny, which have been proposed by STILLE in 1920. These phases in Germany do not always mean very short and intense earth-movements as analyzed by BUBNOFF (1931). Many phases have been reported in Japan; for example, more than ten phases in the Cretaceous period (MATSUMOTO, 1967). That means that the rate of the occurrence of the phases is one per 5 million years on the average. We need precise age determination to correlate the phases among different continents. The cycles of the events in the orogenic zones are good means to correlate the orogenies among different continents. There are, however, some confusions about the conceptions of the orogenic cycles in Japan. The conceptions of the KRAUS's cycle (1927), KOBAYASHI's cycle (or series) (1941), STILLE'S geotectonic cycle (1924) and BUBNOFF'S great cycle (1959) must be distinguished with each other. In Europe we can easily recognize the Paleo-, Meso-and Neo-europe. Therefore the Caledonian, Variscan and Alpine Ära (STILLE, 1928) can be easily distinguished. However, we cannot separate the strata of the Variscan geosyncline into two similar cyclic series of sedimentation to each other; the Caledonian and Variscan cyclic series of sedimentation. The cycles of the events, for example the cycles of the sedimentary facies, must be studied to correlate a orogenic cycle in a continent to another cycle in another continent. There are too many phases in the world. We cannot correlate the cycles only by the phases. Moreover, the end of an orogenic cycle in an orogenic zone is not usually contemporaneous with the beginning of the “next” cycle in the adjacent orogenic zone. Cycles are usually overlapped in age. Angular unconformities are generally thought to show short and intense earthmovements. Some angular unconformities in Japan, however, do not mean the short and intense earth-movements. They have been probably formed by local, but secular earthmovements with the coordination of the regression and transgression which covered the wide area of East Asia. Besides the angular unconformities, the sedimentary facies-change, deformation of strata, and metamorphism and granite-intrusion are used for the recognition of the phases. However, we need precise and comprehensive study to determine the age and intensities of the phases. According to such data for the sedimentary facies-change, the deformation of strata and the age and the metamorphism and others, KOBAYASHI'S (1941) Akiyoshi and Sakawa series of oronization can be recognized in Japan, although there are some opponets. The oldest strata in the Chichibu geosyncline is those of the Silurian. Submarine volcanism was intense during the Devonian and early Carboniferous period. The Akiyoshi series of earth-movements occurred principally in the northern part of the geosyncline during the late Paleozoic and early Mesozoic time, and the Sakawa series principally in the southern part during the late Mesozoic time. The Akiyoshi series of earth-movements began at least in the Permian, was intense in the Triassic and continued to the Jurassic period. The duration of the orogenic cycle from the Silurian to the Jurassic (from the beginning of the geosyncline to the end of the series of the earth-movements) is clearly different from that of the Variscan cycle in Europe. Therefore, we cannot correlate two cyles in view of the duration. Were orogenic cycles produced by the particular agencies for the continents, or produced by one agency which formed an orogenic cycle in one continent earlier and migrated to another continent forming another cycle later ? Such questions, however, remain unsolved.
The Tone River is running through the Kanto Plain which is the largest plain in Japan. Now, the river pours into the Pacific Ocean directly, but in former days the river poured into the Tokyo Bay. According to the construction from 1594 to 1809, the Tone River was jointed to the lower reaches of the Kinu River and became to pour into the Pacific Ocean. We can divide the river basin in the plain into the middle reaches and the lower reaches by the artficial joint place. There are distinct regional differences on the geomorphology and flooding between the middle reaches and the lower reaches. (1) Both the middle and lower reaches were covered with sea water in the transgression which was occured in the middle part of the Alluvial Epoch and the marine layer deposited thick. After that the sea-level was stable for a time, and the peat bog layer deposited. After that the middle reaches was deposited by sand, silt and clay by the Tone River and the lower reaches by the Kokai and Kinu Rivers. But the beginning time of the deposition of the Tone River was faster than that of the Kokai and Kinu. And the marshy land has remained till the comparatively recent time in the lower reaches. (2) The deposition of sand, silt and clay in the middle reaches was big partly because the ground subsidence has been continued partly because the sand, silt and clay which were transported by the Tone River were much in quantity. And the depth of the layer 11 m thick in the Otone Village. On the other hand, the deposition of sand, silt and clay in the lower reaches was few partly because the ground subsidence was smaller, partly because the quantity of sand, silt and clay which was transported by the Kokai and Kinu Rivers was little, partly because the age which the Tone River began to pour into the area was recent. And the depth of the layer is only 1.3 m at Ryugasaki and 0.8 m at Odome. (3) Due to the big deposition of sand, big natural levees had been developed along the former main stream of the Tone and ist distributaries in the middle reaches. So, the nearer to the river the land is, the higher it becomes. When we have floods, the flood water overflows from the river course to the adjacent area. On the other hand, due to the small deposition of sand, there are few natural levees along the river course in the lower reaches. The ground level is horizontal. When we have floods, the flood water flows down slowly on the plain along the river.
The article analizes the data on the petroleum resources, especially their tectonic control in Szechuan which were published before. The author researches for the recent state of Szechuan oil field that has been in progress.