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The rate, mode and time of soil creep were observed by depths using the combination of a strain probe method and a white-sand marker method. The latter method has an advantage to know the total dislocation by depths while the former indicates the time of movement at each depth. Application of the combined method associated with temporal measurement of soil moisture to valley-head slopes covered by natural forest in Sendai, northeastern Japan, in humid temperate climate which was not expected to induce effective freeze-thaw action, revealed the following characteristics of soil creep. The rate of soil creep, which differs considerably from place to place, ranges from almost zero to several centimeters per year, which contains rates several times higher than previously reported ones. The dislocation often occurs synchronously at different positions in the slope in every season. The movement in B and BC horizons, which show almost the same dislocation within the same horizon and abrupt change of displacement at the boundaries of soil horizons, indicates a slide-type movement characterized by micro-slip planes at the boundaries of soil horizons. In contrast, the flow-type movement, in which dislocation is accumulating upward, is dominant in A horizon. This shows the significance of soil horizons in the occurrence of soil creep and suggests the importance of soil creep in soil-horizon differentiation on hillslopes.

29歳,女性。2002年6月,歯科医院にて左下顎智歯周囲炎を治療中,左頬部の腫脹が出現し,急速に両側頚部に拡大してきたため同日当科紹介受診。初診時,左頬部から両側頚部にかけて腫脹し,触診にて握雪感を認めた。CTで上咽頭から上縦隔に広範囲に皮下気腫がみられ,縦隔内にもガス像を認めたため,歯科治療に使用したエアシリンジによる皮下気腫および縦隔気腫と診断した。予防的にレボフロキサシンを投与し6日目には腫脹は消退した。歯科治療により顔面から頚部の皮下気腫が生じることがあることを知っておく必要があると考える。

Tephrochronology-assisted studies of the development of hillslopes, which are segmented by a convex break of slope in northeastern Japan, revealed that lower slope segments began to develop in the early Holocene by consumption of upper segments which mostly developed in the late Pleistocene. Detailed distribution surveys of present-day rapid regolith slides, which were induced by heavy rain in the hills composed of semiconsolidated sandstone and siltstone of the Neogene, showed remarkable concentration of slide heads on lower segments where regolith was distributed not so unequally. Radiocarbon dating suggested that time frequency of regolith slides on lower segments is several times higher than on upper segments in the same hills. On the other hand, in the hills where considerably thicker regolith such as saprolite was maintained on their upper portion, upper segments are also extensively affected by rain-induced regolith slides. Time frequency of regolith slide occurrence on headmost walls in upper segments with thick saprolite is almost as high as that on lower segments of the hills composed of semiconsolidated sedimentary rocks. The spatially and temporally differential occurrence of regolith slides in combination with slow mass movements of creep-type allowed a hypothesis which explains the morphological development of hillslopes in a framework of climatic and hydrogeomorphic change in the late Quaternary. The hypothesis implies that such information of hillslope morphology will be useful in the reconstruction of paleohydrologic environment and its change.

Any riparian forest stands on landforms which are formed, maintained and altered by fluvial processes. Activity of fluvial processes is therefore the matter of principal concern in the study of riparian vegetation. Fluvial processes in the broad sense (Leopold et al. 1964) include both stream action, that is fluvial processes in the narrow sense, and mass-movements, that is customarily classified as hillslope processes (Carson & Kirkby 1972). Although relatively frequent events of flood provide fluvial sediments, mass-movements which occur less frequently bring about alteration of landforms and substrata of not only valley sides but also valley bottoms in upstream watersheds.

Debris-flows, which are a type of mass movement initiated on hillslopes or in channels by either intense rainfall, snowmelt, or rapid runoff, can cause substantial damage and loss of life, particularly in mountainous and hilly areas. Therefore, assessment of debris-flow hazards is imperative for disaster prevention and watershed management in montane environments.

Large-scale landform transformations for various purposes of land developments have been recently active in Japan. They have required the researchs from the viewpoint of anthro-ogenic geomorphology which contains both man-made and man-induced landforms and p related phenomena in its scope. This paper reveals the recent trends of the change in types of landform utilized and estimates the magnitude of man-made landforming processes in the intensely developed lands in Japan. Because the statistics showing the actual states of landform transformation have not been sufficiently prepared yet, the estimation of magunitude of artificial landforming processes in this study progresses inevitably in a felicitous combination of selected detailed surveys and effective generalization. First, landform modification types and magnitude are investi-gated with the aid of very large-scale scheme drawings etc. at the small number of typical development sites for each purpose and in each type of landform. The area of develop-ment and the volume of artificially-removed earth provide the simple indices of landform-modification magnitude. The greater volume between artificially cut material and filling one is used to represent the volume of artificiallyremoved earth in the site because most of earth cut from higher location is usually applied for filling in the lower location within the same development site except for ones in the flat lowlands and the reclaimed lands. The normal depth of surface disturbance is defined as the average of the ratio of the above volume to area of the site for both every development purpose, e. g. residential, industrial, agricultural, etc., and every geomorphic location which is classified into the follwing four intermediate-scale geomorphic units: the lowlands (Holocene alluvial and coastal plains), the terraces (mostly of late-Pleistocene age), the hills (mostly composed of early-Pleistocene and/or Neogene de-posits with mid-Pleistocene cover in part) and the mountains. The areas for several pur-poses of development sites, which are usually provided with administrative districts, are also retotalized according to these geomorphic units. The normal depth of surface disturbace and the total area of development, both of which are arranged according to the development purposes and the intermediate-scale geomor phic units, are applied for the estimation of the total volume of artificially-removed earth. Some results of the estimation are as follows: 1. The land development for various purposes became very active around 1960 and has been advanced with distinct decrease in the mid-1970's. The trends correspond well with changes in the national-scale socio-economic activity. 2. The rapid increase of intense land-developments since 1960 has proceeded in concurrent with the remarkable changes in locational condition of landform for residential, agricultural, and industrial sites from the lowlands and terraces to the hills, and further to the mountains in the case of agricultural development. For instance, more than 40% (in area) of the newly-developed residential sites are located in the hills. Moreover very extensive area of golf courses, which may exceed the total area of residential development, has been developed during the same period and most of them are located in the hills. 3. The increase of development area and the changes in its locational condition of landform to the hills have caused distinct rise of artificially-removed earth volume. The total volume of earth removed artificially during 20 years since 1960 in Japan may reach the order of 1010m3, which means 1 or 2×103m3 of earth material has been removed an-nually from every1km2 area.

The alluvial plain along the lower Nakama River on Iriomote Island can be divided from the shore landward into the following four sections: 1) a section consisting of the estuary, the coast of which is occupied by mangrove forests with Avicennia marina and Sonneratia alba constituting the seaward fringe; 2) a section of the delta covered with mangrove forests, dominated by Bruguiera gymnorhiza and/or Rhizophora stylosa, but also with some Kandelia candel but not including Avicennia marina or Sonneratia alba; 3) a section consisting of low, flat mounds composed of estuarine deposits formed during the Holocene transgression and covered with Pandanus tectorius thickets; 4) a section of a floodplain on which Barringtonia racemosa forests are prominently distributed.This paper, as the second part of a study on vegetation-landform relationships on this alluvial plain, deals mainly with detailed descriptions of the relationships in the third and the fourth sections mentioned above. In those sections, natural levees have developed along the Nakama River and its branches, and mixed forests of Machilus thunbergii and Mallotus paniculatus are found there. They are distinguishable from Barringtonia racemosa forests which compose a swamp forest in the back swamps and the Pandanus tectorius thickets on the flat mounds of the estuarine deposits. Colluvial slopes are occupied by other Barringtonia racemosa forests including Cyclobalanopsis miyagii.Close correspondence between the areal extent of landform units and plant communities is found both in small-scale and in micro-scale. The landforms of the area were outlined in the course of deposition during the Holocene transgression and have been differentiated by the processes that followed. The arrangement of the plant communities on this alluvial plain can be interpreted in terms of both present and historical land-forming process types.

The growth behavior of two transplantable osteosarcomas, spontaneously occurring and a carcinogen, 4-hydroxyamino-quinoline 1-oxide (4-HAQO), induced in Fischer 344 rats are described. The transplantability of those neoplasms was more than 80% and their doubling time ranged from 2.8 to 5 days. At the present time, the tumor occurring spontaneously is in the 17th generation and the 4-HAQO induced one is in the 14th generation. In spontaneously occurring osteosarcoma, numerous osteoid formation was observed but by serial transplantation osteoid formation decreased and disappeared by the 10th generation. On the other hand, in 4-HAQO induced osteosarcoma, osteoid formation was maintained by serial transfer and pulmonary metastasis occurred in animals receiving subcutaneous transplantation. These results provide a useful experimental model for studying tumor cell differentiation in forming osteoid and pulmonary metastasis.

The previously circulated views on the stratigraphy of terrace deposits along the southeastern coast of the Kii peninsula are amended and the periods of slope instability in the same area are discussed in this paper.Sequence of coastal terraces with stratigraphy of terrace deposits is summarized in Fig. 6. Sealevel change including crustal movement, which may be continuous uplift with tilting to the north, as shown in Fig. 7 is derived from the sequence. Three major transgressions in the middle and late Pleistocene are noticeable. The Shingu Gravel indicates the development of alluvial fan in the age just prior to the maximum of the regression which precedes the transgression exhibited with the Kumanoura formation.Old debris-flow deposits are laid on a part of dissected piedmont gentle slopes and colluvio-fluvial deposits fill small valleys dissecting the terraces. Stratigraphic relation of such slope deposits to terrace deposits suggests the periods when a lot of slope deposits are produced, namely the periods of slope instability. Increase of fluvial deposits as the Shingu Gravel may also reflect such a condition. The periods of slope instability in the area seem to coincide with the ages of low sealevel.

On May 16th, 1968, many slope failures occurred in the southeastern part of Aomori prefecture by the severe shock of the Tokachi-oki earthquake after a heavy rainfall of 160-210mm in preceding three days. Most of slope failures were concentrated in the small tributaries of the Asamizu River which had suffered the heaviest rainfall.Each failure site is composed of erosional part, runway of collapsed materials and depositional part of them. According to the form of its erosional part, each failure is classified into “seauper” or “plane” type. The former is situated in the small shallow depression excavated in the upper gentle slope of valley side dissecting the uplands and the latter on steeper straight slope. Runways are varied in length, but at this time, slope failures are characterized by long-distance transportation of detrital mass in proportion to its volume. The runways on slope surfaces and narrow valley floors are not eroded and covered with a little debris.Rapid stream of mud with large blocks soaked by water as the result of the shock of the earthquake flew down through the runways and spread over the paddy fields in the valley plain like a sheet or deposited in the lower part of V-shaped valley. Materials connected with these slope failures are, from the upper to the lower, black surface soil, brown subsoil, yellowish brown volcanic ash with yellow pumice grains and greyish white clayey pumice, but underlying coase pumice was not disturbed. The permeability and liquidity of these tephras, as well as their distribution, are the basic factors of the event.

On May 16th, 1968, at 09:49, an earthquake (Tokachi-oki Earthquake) with the magnitude of 7.8 occurred on the Pacific side of Tohoku and Hokkaido. Many of artificial embankments such as railroad basements, highway constructions and earth-fill dams were severely damaged. The connecting slopes to bridges were subsided in many cases, but the bridges were undamaged.On the alluvial lowlands, especially newly reclaimed or graded lands for factory areas around urban districts of Hakodate, Aomori, Mutsu and Hachinoho, there occurred many cracks, depressions and sand-jetting.It is characteristic of this earthquake that some steel-concrete buildings on the terrace surface collapsed.Land falls and landslides in the valleys dissecting the uplands to the west of Hachinohe City were the most disasterous accidents, in which the earthquake acted as a trigger after a heavy rain amounting 160mm in three days.

In the course of study of hill landform, it seems necessary to investigate not only the initial surface of the hill which is shown as accordant-height summits and is conceived to indicate a baselevel of erosion in an earlier age, but the processes of destruction or modification from initial surface into the present relief, the processes suggested, in the shapes of present valleys and slopes.In the hilly land shown in Fig. 1, situated to the south of Sendai, there are two levels of accordant-height summits, HI and HII Levels. The Levels cut the Miocene Formation in the major part, and, in the minor part HI Level is underlain with weathered round gravel bed of the middle or lower Pleistocene. Above the summits of HI and HII Levels, protrude some peaks grouped into HI. Theose Levels are surrounded by a lowlying hill surface, HIII originated from the denudation surface formed prior to the fall of Yellow Pumice. Characteristic gentle slopes and shallow valleys were formed over whole area shown in Fig. 1, when the TI terrace formation proceeded. That terrace is correlated to the last low sea level by NAKAGAWA et al. (1960). Those slopes and valleys are in the surface forms continuous not only to TI but to the higher Levels especially to HI and they cut Yellow Pumice Bed, Such landforms, judged from their geological and morphological features, seem to be mainly formed with a kind of mass-movement on the valley-sides. Gentle slopes here may be Cryopediment by WAKO (1963). Through the formation of such geomorphological elements, Coarsetexthred landscape (COTTON, 1963) was arranged over the whole area, later some parts are reduced into Fine-textured landscape (COTTON, op. cit.) through the V-shaped valley formation. The Coarse-textured landscape is preserved better where the local baselevel is high. Throughout those processes, geological structure has continuously influenced the lartdform development and certain tectonic, movements took place even after the formation of TI surface.

A valley-head area, where a stream is elongating towards watershed, is composed of the following five micro-landform units: Crest slope, Side slope, Head hollow, Head floor, and Channelway; which is followed with Bottomland (Fig. 1). The conclusion is drawn from the study on landscapes of some hill-lands in eastern Japan (Fig. 2) and may be applicable to the whole hilislopes with adequate soil and vegetation cover in humid temperate zone.Hydrological conditions and present geomorphic processes prevailing in each micro-landform unit are listed in Tab. 2. The conditions and processes are inducible from characteristic surface features and soil morphology of each unit. The induction is supported with knowledge in slope hydrology, especially with facts and theories concerning throughflow (Fig. 3).These processes are considered to be not generative but modificatory agent to a valley-head. Somewhat catastrophic processes such as large landslide (with about 103m3 of debris), which is also provoked with throughflow, may be concerned with outbreak of a new valley-head. It is suggested with morphological and stratigraphic evidences in some micro-landform units.The extent and proportion of each unit in a valley-head area may reflect the total morphogenetic condition of the area. Especially interzonal comparison of the distance between the headmost divide and the point of Channelway initiation (modified 10 of Horton) must be significant from a climato-geomorphological viewpoint.

On several coastal terraces along the northeastern margin of Kitakami Massif, it is observed that a certain tephra deposit was transported on slope surfaces and then buried by the younger tephra. The lowermost horizon of the covering younger tephras is stratigraphically settled at the upper part of Takadate Volcanic Ash and Haehinohe Pumice.Such disturbed layer showing active movement of materials on the former slope surfaces is not observed in other horizons of the tephra sequence in the area.From this fact, it is surmised as follows : there existed some conditions that caused slope-instability concurrent with Upper Takadate Ash fall and preceding Haehinohe Pumice fall. Slopes were disturbed in different periods in accordance with their topographic sites.Upper Takadate Ash, covering the deposits of the coastal terrace of about 10m a.s.l, partly includes angular boulders splitted from the stacks on former abrasion platform and is partly varied in mxied deposits of clayey ash and breccia. There is organic clay directly overlain with Haehinohe Pumice of which C-14 age was dated to 12700±270 yrs. B.P. This clay is abundant in pollens of Picea. These data may suggest the age and environment in the period of slope-instability.

Several types of slope deposits were observed in undulating lands near the northern margin of Kitakami Massif. Stratigraphic relations of the deposits were investigated tephrochronologically. The radiocarbon ages of several tephra layers have already been known. The processes by which the slope deposits were formed were studied from their facies, their relations to landforms and lithology, and paleoenvironmental data including pollen analysis. As the result, the following four periods were discerned as 'periods of slope instability' when mass-movements on slope surfaces were more active than at the other periods.The period I: It is earlier than the late Pleistocene and might be warmer. Piedmont gentle slopes composed of removed materials of granodiorite were built at the foot of the mountains of the same rock.The period II: It is the cooler late Pleistocene when gentle slopes composed of screes were formed, smoothly continuing to or covering terrace surfaces.The period III: It is the latest Pleistocene and is subdivided into the subperiod III-1 about 30, 000 years B. P. and the subperiod III-2 about 15, 000 or 20, 000 years B. P.. Palynological data suggest colder climate of those days which is concordant to common knowledge. The same landforms as those of the period II were formed during the subperiod III-1, and derasional valleys were configurated through the subperiod III-1 and III-2. Those shallow concave valleys were terraced and flat-floored valleys were excavated in the Holocene. The morphological evidence suggests the intensification of fluvial action at about the time of the Pleistocene-Holocene boundary. Rocks were deeply weathered on the summits of the residual mountains and tali were formed at the foot of steep slopes during the period III.The period IV is in the Holocene and was the least unstable among the four periods of slope instability.