We may say that the terrestrial climate has been rather unstable during the period since the beginning of Quaternary up to the present. The so-called Milankovitch's solar curve basing on his summer curve has been used by many researchers in order to explain the Quaternary glacial and interglacial alternation. His another curve, the winter curve, suggests a latitudinal insolation difference which brings about a change of latitudinal temperature gradient in winter as in the case of summer. Therefore, the change of winter atmospheric circulation may possibly create a new glacial or interglacial period, though he did not mention such circulation regime. The minimum temperature period showed in his summer-half-year solar curve corresponds to the greatest temperature gradient in his winter curve at the middle and the high latitudes in northern hemisphere. If a meridional circulation type previals in winter, precipitation and temperature patterns in northern hemisphere become favorable to form new continental glaciers in the specified regions. The author has criticized these considerations with the view point of recent researches concerning the global radiation, the atmospheric general circulation and also the meteorological events.
The Far East monsoon regime is a consequence of the interaction of both planetary and regional factors. When the westerlies over the Eastern Hemisphere are weak in winter, the stational trough of the planetary wave, which is located normally in the neighborhood of the Japanese islands, tends to retreat in the Japan Sea side, producing the monsoonal climate, that is to say, the lower air temperatures in the south-western Japan and more snowy winter in the Hokuriku District. On the contrary, when the westerlies become stronger, the trough moves across the Japan Island to the Pacific side, resulting the non-monsoonal winter climate, warm winter in the southwestern Japan, less snowy in the Hokuriku District and more rainy in the Pacific coast. In summer, the trough, which is normally located farther west in the Japan Sea, moves westwards or eastwards, corresponding to the weaker or stronger westerlies, and produces hot-dry summers or cool-rainy summers in Japan. In other words, the winter and summer monsoons in the Far East change their vigor in contrast with the intensity of the prevailing westerlies throughout the year, and this is the reasons why the cold-snowy (warm-less snowy) winters correspond to hot-dry (cool-rainy) summers, and the curve of 11-year running means of the annual means of wind speeds at the summit of Mt. Fuji (3782m) changes opposite to those of the annual amplitude of air temperatures at various points in the central Japan. Through the rhythm of the decade means of summer air temperatures in the north-eastern Japan and the running means of the amount of January precipitations on the Japan Sea coast, a significant trend of long-term change is noticable, which must be attributed to the north-southward displacement of the climatic zone. The northward shift or the southward retreat of the climatic zone generally appears in company with the weak or vigorous state of the prevailing westerlies. Consequently, in the case of Japanese climate, the effect of the Far East monsoons on the winter climate, for instance, the lowering or rising air temperatures due to the change of the Far East monsoon, objects to the effect influenced by the north-southward displacement of climatic zone, while, in summer, both effects cooperate with each other. However, in the estreme cases of the displacement of the climatic zone, the global effect exceeds the regional effect of the Far East monsoons, producing the extreme case of“Little Climatic Optimum” with warm-less snowy winters and hot-dry summers and the extreme case of“Little Ice Age”with cold-snowy winters and cool-rainy summers. It is beyond question that the most favorable condition for the accumulation of snow and ice must be the extreme case of“Little Ice Age”distinguished with much snowfalls, lower air temperature in all seasons, and rainy summers associated by the reduced durations of sunshine. The climate in the first half of XV Century, for instance, is estimated to be the extreme case of“Little Ice Age”from the various records of decuments. In accord with the estimation, the 14C dating test on the wood which was discovered by Horie (1968) in the outwash deposit of Shirouma Kitamata (1620M) gives 520±80 years B. P. Howeve, the duration of extreme period of“Little Ice Age”is not so long as far as it concerns within historical times. The climate of (warm-winter)-(cool-summer), which is caused by the predominant westerlies and distinguished with the intensified activities of Lows in the surroundings of the Japan Island, is also favorable, to a certain exextent, for the accumulation of snow.
In the present paper, the geohistorical succession of the vegetation in Japan (chiefiy Honsyu) during the Würm Glacial Age is researched into from the plant fossil records (remains and pollen) and geochronological evidences. Moreover, some preliminary considerations on the climatic change during the above mentioned age are given based on the results of research in the geohistorical succession of the vegetation. Some noticiable facts are as follows; 1) At the times of about 12, 500y. B.P. (in radiocarbon years), the vegetation indicating a somewhat warmer climatic condition appeared in some areas, such as Oomi in Kinki District and Niigata in Chubu District. 2) At the times of about 18, 000y. B. P. (in radiocarbon years), the typical vegetation now distributed in the subarctic or subalpine zone in Japan occupied the lowland of the northern part of Honsyu. It indicates that the coldest episode appeared at this term in Japan. This term may be referred to the Maximum Würm glacial. 3) During the term of the Würm Glacial Age older than 21, 000y. B.P. (in radiocarbon years), the vegetation was characterized by the forest, composed chiefly of the plants now distributed in the subalpine zone and intermingled with the plants now distributed in the montane zone. It indicates that the climate in this long term was affected more by the somewhat humid condition than the climatic condition in the subarctic or subalpine zone. Especially, at the short term of about 25, 000y. B.P. (in radiocarbon years), the vegetation was composed chiefly of the plants now distributed in the temperate or montane zone in Japan. It indicates that the minor warm episodes appeared in the times of about 25, 000y. B.P. The appearance of the same episodes may be expected in the somewhat longer term of about 40, 000y. B.P. (in radiocarbon years).
In present paper some fossil forms of frozen ground phenomena such as earth hummocks (Fig. 1), sorted patterned grounds (Figs. 3 & 4), festoon: vertical stones (Figs. 4 & 5), involutions (Figs. 7 & 8), and ice-wedge casts (Fig. 6) are described. The zonal distribution of active frozen ground phenomena and related environments are tabulated from some literatures as well as the results of our own survey on them in Japan (Table 1). Paleoclimate of the last glacial period in the esatern part of Hokkaido is considered after distribution of fossil frozen ground phenomena comparing with distribution of active ones. Volcanic ash layers and river terraces are surveyed to determine tephorochronologically the age of phenomena. The main results are as follows. All kinds of frozen ground phenomena, even earth hummocks, carry involution structures in cross section (Fig. 2). Stratified sediments such as volcanic ash layers clarify involution structures. In Japan, the southern limit of active earth hummocks coincedes approximately with +6°C mean annual isotherm. Therefore, buried earth hummocks and small-scale involutions do not indicate ancient cold climate in eastern Hokkaido where present mean annual temerature is nearly+6°C. Festoon, a kind of involution, can easily be found in fine sediments overlying river terrace gravels. Because of prevention of dense vegetation cover gravels do not reach the ground surface to form sorted patterned ground in most cases although some fossil sorted patterned grounds are found. Vegetation profited by warmth in summer sets the limit of sorted patterned grounds on nearly 0°C mean annual isotherm in central Japan and on a isotherm of somewhat lower than 0°C in Hokkaido. Some large-scale involutions (Fig. 8) may be cross sectios of palsas. Ice-wedge casts, indicators of ancient permafrost, are also found in the lowlands of eastern Hokkaido. Based on Péwé's observation decreasing of temperature at the time should be estimated as 12°-14°C. In this region ice-wedge casts indicating the maximum coldness are buried by a markable layer (Erimo Volcanic Sand: Spfa; 32, 200 14C yr.B.P.). It is, therefore, concluded from chronological studies of river terraces and volcanic ash layers that in this region the maximum decreasing of temperature precedes the maximum lowering of sea level observed all over the world in 18, 000-20, 000yr.B.P.
In this paper, the authors report the existence of permafrost at Mt. Taisetsu, Hokkaido, and disdiscuss the climatic significance of permafrost there from a viewpoint of the Quaternary palaecolimatology. Many researchers have observed that patterned grounds, especially sorted circles well developed on many gentle slopes and small depressions at Mt. Taisetsu. And recently it was reported that the networks of fissures of the ground which are similar to large scale ploygons on permafrost in Alaska were found at some places at Mt. Taisetsu. Those sorted circles and nets of fissures suggest the existence of permafrost which is believed to be either relict or recent. By our on-the-spot investigations at Mt. Taisetsu, permafrost was found on one of flat summits (2, 150m) by boring tests and geophysical methods. The maximum depth of the active layer was nearly 2m and the maximum depth of the lower limit of this permafrost was estimated to be 15m or larger. Its frozen soils consisted of weathered fine sands and gravels derived from an andesite bedrock, which are considered as frost-action products. Large sorted circles were form ed on the surface of permafrost. The mean annual temperature and degree-days in this area were calculated as -3.1°C and 2, 400 degree-days by extrapolations on the basis of meteorological data in Asahikawa. The estimated temperature and degree-days suggest that this area has the same climatic conditions as those in central Alasak, where discontinuous permafrost is distributed. Introducing the Popov's theory about the formation of an ice-wedge, we estimated the palaeo-temperature of the surface of the extended permafrost to be -7°--8°C (mean annual temperature) during a past colder period than present. Comparing the estimated chronology of the permafrost with the chronology of permafrost in Alaska and Siberia, and considering the field observations of fossil ice-wedge casts and polygons in Hokkaido, we may conclude that the permafrost at Mt. Taisetsu formed at the last ice age, after then gradually has become smaller, adapting itself to the present climatic conditions.
Geomorphology of terraces and related features around Sapporo and several other districts in Hokkaido have been compared. The cause of geomorphic change in the last Glacial Age and its relation to climatic change are briefly discussed and reviewed. In that Age nearly same fluvial geomorphic changes occurred in these places. The large accumulation in the valley and piedmont region is found to have occurred once. Alluvial fan and aggradational terrace of the substage were already in dissectional phase at the time some what earlier than 30, 000 14C years B.P. The cause of the accumulation may be of climatic origin, but the correlation between climatic records and geomorphological events in these regions is not clear.
This paper describes the results of investigation on the relation between the climate and soil geographical characteristics of the northern Hokkaido. In order to make clear the effect of climate on the soil formation, heat balance climatological methods have been applied. The results obtained are summarized as follows. 1) In the northern Hokkaido, the annual value of the net radiation is in the range from 32 to 35 kcal/cm2·yr and monthly maxima (7±0.5kcal/cm2) appear in the early temperate season (May-July). Judging from the close relation between the net radiation and latent heat flux and annual summations of daily mean temperature (>10°C), it is concluded that the net radiation is a fundamental element which reveals the thermal condition of the environment. 2) The atmospheric humidity is estimated quantitatively by the radiative dry index, that is the ratio of the net radiation to the amounts of heat required to evaporate all of the annual precipitation. Because of the remarkable local variation of the annual value of precipitation, considerable discrepancies of figures among meteorological observatories are noted, though the annual value of heat balance components is almost constant throughout the area. 3) The area where the annual mean value of the radiative dry index is less than 0.5 coincides very well with the zone of weakly podzolized soils. The climate of this area differs apparently from that of the continental zone of podzolic soils which were described by MA et al (1958) and BOROBUEV (1963). Generally speaking, the climate of the northern Hokkaido is warmer but more humid than that in the far eastern districts of continental Asia. 4) Seasonal dynamics of the hydro-thermal condition is controlled by the thawing and water deficit (precipitation minus potential evapotranspiration) during the eary temperate season. Judging from the occurrence of high annual precipitation, prolonged thawing season and scanty net radiation in the late temperate season, it is concluded that the leashing out water regime is continued almost through the year in the podzolic zone of Hokkaido unless the low permeable layer in the profile prevents the deep percolation of excess water. However, in the central and southern seaboards of the Okhotsk where dry climate during the early temperate season is evident, the downward movement of water through the profile is strongly reduced during the period from April to July. Consequently, the water regime in the area tends to become the periodical leaching out water regime. The main reason of the soil geographical zoning in the northern Hokkaido might be attributed to the cool-humid climate and its local or seasonal variation as described above. 5) It should not be overlooked that the formation and composition of catenary associations on flats and depressions of terraces or subdued terrains are also affected by the cool-humid climate and poor internal drainage of the sediments. 6) Furthermore, one has to point out the influence of the climate as it is highly probable that the main soil parent materials on uplands and hills, such as consolidated tuffaceous clays and slope sediments, were made under the cryopedological processes occurred during the past cold and humid ages.
In this paper, the outline of the meteorologic and the oceanographic investigation on the drift ice formation in the Sea of Okhotsk is given. The main factor which affects the ice formation in the Sea of Okhotsk is the existence of a thin mixing layer of very low salinity less than 100m in thickness on the surface of the Sea. The origin of this low salinity water is considered to come from the inflow of large amount of water from Siberia. According to FUKUTOMI mean total amount of ice in the Sea of Okhotsk is approximately 120×103m3 in winter.
BLAKISTON was the first who studied scientifically the distribution of mammals and birds in Hokkaido and in north-eastern part of the Main Land. He insisted from the zoological point of view that Hokkaido was once a part of Asiatic Continent. According to him Tsugaru Strait is an important line of demarcation of animal distribution in northern Japan (BLAKISTON, 1883). However, HATTA (1913) did not agree with BLAKISTON when he investigated Reptilian and Amphibian fauna of Sakhalin comparing with those of Hokkaido. For example the snake of Sakhalin is Vipera berus which occurs in northern part of Eurasian Contient while the snakes of Hokkaido are those which are very common in the Main Land. Therefore, he pointed that Soya Strait between Sakhalin and Hokkaido is zoogeographically more important than Tsugaru Strait. There has been a confusion concerning the origin of animals in northern Japan. Recently Salamandrella keyserlingii which is a continental salamander has been found in Hokkaido. The pika and continental lizard, Lacerta vivipara have been also captured in Hokkaido. From this HATTA's opinion seems to be denied. BLAKISTON did not mentioned why the deer and the raccoon dog which are inhabitants of the Main Land are found in Hokkaido. Recently paleontological as well as geological studies of Japan has been much advanced and it has been ascertained that in ancient glacial period either Soya Strait or Tsugaru Strait disappeared as a result of the lowering down of the sea level. Either BLAKISTON's theory or Hatta's opinion is recognizable when we take into account ancient geological changes of northern Japan. However, we shall pay attention to the migration of animals by means of drift ice which has sometimes brought the fox from Kurile to Hokkaido.
From the study of fossils the present status of mammals in Japan is considered to have appeared since the Diluvian epoch of Quaternary. Most of the present mammals in Japan show close relation to those of the Asiatic Continent and the distribution pattern shows that there occurred animal interchange between the both areas in ancient times. Prototype of mammalian fauna of Hokkaido seems to have been constructed up to Post-glacier period after the isolation of Hokkaido from the neighbouring areas. At present, mammalian fauna of Hokkaido includes 19 sp. and 34 subsp. belonging to 34 genera, 14 families, 6 orders (see Table 1). The characteristic of mammalian fauna of Hokkaido is consisted in a mixed existence both of northern cold zone species and of southern temperate zone species including some great sphere ones. There are many marine animals which are rare in the Main Island. The existence of many northern cold species in Hokkaido and South-Kuriles shows close faunal relation to Sakhalin and Primorskii. Three genera of the vole, namely Clethrionomys, Aschizomys and Eothenomys; two species of the shrew, namely Sorex minutissimus and Sorex hosonoi; two species of the squirrel, namely Sciurus vulgaris and Sciurus lis; and two species of the hare, namely Lepus Brachyurus and Lepus timidus are very similar respectively in all aspects. However, no phylogenetic study of the animal has been made, though the matter is very interesting. The occurrence of Crocidura dsinezumi, Sorex minutissimus and Ochotona hyperborea in Hokkaido is particular. Their ecological and zoogeographical studies are necessary. More species of mammals in Kuriles may be added in future.
Recent archeological investigations in Hokkaido have shown that while the prehistoric culture in the southwestern part of the island was closely related with that in the northern part of Honshu throughout the Jomon and epi-Jomon Periods, those in the central and northeastern parts of the island comprised various elements quite alien from Japanese Jomon culture. In succeeding Satsumon Period and historic times, the cultures in Hokkaido have been relatively homogeneous, with the exception of the Okhotsk Coast area which was temporarily occupied by the Okhotsk Culture from the end of the epi-Jomon through the Satsumon Periods. Human skeletal remains excavated so far in Hokkaido were reviewed separately for the three prehistoric cultural areas: the southwestern, the northeastern and the Okhotsk areas. Those from the Jomon sites in the Southwest were found to be closely related in morphological features as well as in metric characteristics with the skeletal remains of the Jomon population in Honshu. Those from later periods in the Southwest, however, showed gradual change to a form more closely resembling the modern southwestern Ainu. On the other hand, the skeletal remains from the Northeast were found to have been very close morphologically to the modern northeastern Ainu since the beginning of the Jomon Period. Skeletal remains derived from the Okhotsk culture area, as represented by the Moyoro shell-heap materials, were found to resemble northern neighbours such as the Sakhalin Ainu, the Gilyak and the Ul'chi. It was tentatively concluded from the above findings and some distance analysis that the form of the Hokkaido Ainu proper was best represented by the modern Ainu in the northeastern part of the island exclusive of the Okhotsk Coast area. Craniological materials collected mainly from the northeastern part of the island by KOGANEI (1893) were analyzed by Mahalanobis' distance method for the purpose of seeking morphological proximity among fifty populations in northern Eurasia, Far East, Oceania, and North America. Among other things, unexpected resemblance was detected between the Ainu and the prehistoric human remains from Alati-Sayan highland in Siberia (ALEKSEEV, 1961). Further developments in archeology and paleoanthropology in Siberia and Hokkaido are needed before any conclusion can be drawn from this interesting finding.
In this paper, the author discussed man's adaptation to the cold and formation of the northern Mongoloids in the light of human adaptability to the climatic conditions. It is widely known that the mammals generally show several adaptations to the climate, among which the most effective factors seem to be the light and the temperature. For instance, in the field of mammalian ecology, the rules proposed by GLOGER, BERGMANN and ALLEN are generally accepted, and they can be also applied on microevolution of the human populations to some extent. Thus, it is said that the Caucasoids have adapted to the cold and moist climate with low radiation of ultraviolet rays, and the Negroids to the environment with high temperature and excessive radiation of ultraviolet rays. In parallel to this, the Mongoloids are regarded as having adapted to the very low temperature and dry weather. However, adaptation in this direction has likely occurred in or just after the latest stage of the Upper Paleolithic, because the Mongoloids from this stage such as the Upper Cave Men show almost no evidence of adaptation to the extremely cold temperature. In this respect, the modern Mongoloids living in the arctic areas may be regarded as the people who acquired their adaptability to the cold in relatively recent stages of evolution. On the other hand, we can find some other populations who retain more or less archaic characters of the Mongoloids in peripheral areas of the Asian and the American Continents, and even in the sub-arctic areas. For instance, the Ainu has so far been attributed their origin to the Caucasian stock. Several recent findings on their blood composition, dermatoglyphics and dental characteristics, however, show close affinity to the Mongoloids. On the other hand, the Ainu still shows unique characteristics in quite rich beard and body hairs, relatively thin subcutaneous fat, partially projected facial bones, etc., and these characteristics do not show high degree of adaptability to the cold climate. On the basis of these fact, it is quite likely that the Ainu might be one of branches of the Mongoloid stock who has less experience to live under the extremely cold environment, and still retains some archaic characters compared with the neighbouring populations. Naturally, this hypothesis should be checked by several other data from the fields of anthropology, prehistory, geology, and other related sciences.
The study of the language or foklore of the tribe may suggest what kind of the climate their ancestors experienced in the past. The author has tried to discover this from a study of the Ainu language and its oral tradition. The Ainu language, like English or Japanese, does not have many different morphemes for snow or ice when compared with Eskimo or Manchu. In some of “Yukar” legends of the Ainu, the serpent is thought to be a kind of taboo among the ancient Ainus. The snake was an alien creature, inhabiting no single category of the Ainu configuration of nature (sky, mountains, land, and water), but forever acrossing the boundaries between them. It is thus inferred that the ancient Ainus had some contact with snakes, animals that can hardly survive in the absence of a warm summer. From this we may venture to guess that the ancient Ainu people may have lived in a mild climate, or that the original Ainu culture might have dedeveloped in a land with a snowy winter and a warm summer. Ice and icebergs were not a feature of their world. The regions which the Ainus inhabited were sub-frigid at their coldest and there is no evidence that the Ainus had come from a very cold land such as the arctic regions.