Part 17

_Geology._--It is a popular belief that the islands of Japan consist for the most part of volcanic rocks. But although this conception might reasonably be suggested by the presence of many active and extinct volcanoes, Professor J. Milne has pointed out that it is literally true of the Kuriles alone, partially true for the northern half of the Main Island and for Kiushiu, and quite incorrect as applied to the southern half of the Main Island and to Shikoku. This authority sums up the geology of Japan briefly and succinctly as follows (in _Things Japanese_, by Professor Chamberlain): "The backbone of the country consists of primitive gneiss and schists. Amongst the latter, in Shikoku, there is an extremely interesting rock consisting largely of piedmontite. Overlying these amongst the Palaeozoic rocks, we meet in many parts of Japan with slates and other rocks possibly of Cambrian or Silurian age. Trilobites have been discovered in Rikuzen. Carboniferous rocks are represented by mountain masses of _Fusulina_ and other limestones. There is also amongst the Palaeozoic group an interesting series of red slates containing Radiolaria. Mesozoic rocks are represented by slates containing _Ammonites_ and _Monotis_, evidently of Triassic age, rocks containing _Ammonites Bucklandi_ of Liassic age, a series of beds rich in plants of Jurassic age, and beds of Cretaceous age containing _Trigonia_ and many other fossils. The Cainozoic or Tertiary system forms a fringe round the coasts of many portions of the empire. It chiefly consists of stratified volcanic tuffs rich in coal, lignite, fossilized plants and an invertebrate fauna. Diatomaceous earth exists at several places in Yezo. In the alluvium which covers all, the remains have been discovered of several species of elephant, which, according to Dr Edmund Naumann, are of Indian origin. The most common eruptive rock is andesite. Such rocks as basalt, diorite and trachyte are comparatively rare. Quartz porphyry, quartzless porphyry, and granite are largely developed." Drs von Richthofen and Rein discuss the subject in greater detail. They have pointed out that in the mountain system of Japan there are three main lines. One runs from S.W. to N.E.; another from S.S.W. to N.N.E., and the third is meridional. These they call respectively the "southern schist range," the "northern schist range," and the "snow range," the last consisting mainly of old crystalline massive rocks. The rocks predominating in Japan fall also into three groups. They are, first, plutonic rocks, especially granite; secondly, volcanic rocks, chiefly trachyte and dolerite; and thirdly, palaeozoic schists. On the other hand, limestone and sandstone, especially of the Mesozoic strata, are strikingly deficient. The strike of the old crystalline rocks follows, in general, the main direction of the islands (S.W. to N.E.). They are often overlain by schists and quartzites, or broken through by volcanic masses. "The basis of the islands consist of granite, syenite, diorite, diabase and related kinds of rock, porphyry appearing comparatively seldom. Now the granite, continuing for long distances, forms the prevailing rock; then, again, it forms the foundation for thick strata of schist and sandstone, itself only appearing in valleys of erosion and river boulders, in rocky projections on the coasts or in the ridges of the mountains.... In the composition of many mountains in Hondo (the main island) granite plays a prominent part.... It appears to form the central mass which crops up in hundreds of places towards the coast and in the interior. Old schists, free from fossils and rich in quartz, overlie it in parallel chains through the whole length of the peninsula, especially in the central and highest ridges, and bear the ores of Chu-goku (the central provinces), principally copper pyrites and magnetic pyrites. These schist ridges rich in quartz show, to a depth of 20 metres, considerable disintegration. The resulting pebble and quartz-sand is very unproductive, and supports chiefly a poor underwood and crippled pines with widely spreading roots which seek their nourishment afar. In the province of Settsu granite everywhere predominates, which may be observed also in the railway cuttings between Hiogo and Osaka, as well as in the temples and walls of these towns. The waterfalls near Kobe descend over granite walls and the _mikageishi_ (stone of Mikage), famous throughout Japan, is granite from Settsu.... In the hill country on the borders of Ise, Owari, Mikawa and Totomi, on the one side, and Omi, Mino and Shinano, on the other, granite frequently forms dark grey and much disintegrated rock-projections above schist and diluvial quartz pebbles. The feldspar of a splendid pegmatite and its products of disintegration on the borders of Owari, Mino and Mikawa form the raw material of the very extensive ceramic industry of this district, with its chief place, Seto. Of granite are chiefly formed the meridional mountains of Shinano. Granite, diorite and other plutonic rocks hem in the winding upper valleys of the Kiso-gawa, the Saigawa (Shinano river) and many other rivers of this province, their clear water running over granite. Also in the hills bordering on the plain of Kwanto these old crystalline rocks are widely spread. Farther northwards they give way again, as in the south, to schists and eruptive rocks. Yet even here granite may be traced in many places. Of course it is not always a pure granite; even hablit and granite-porphyry are found here and there. Thus, for instance, near Nikko in the upper valley of the Daiya-gawa, and in several other places in the neighbouring mountains, a granite-porphyry appears with large, pale, flesh-coloured crystals of orthoclase, dull triclinic felspar, quartz and hornblende." "From the mine of Ichinokawa in Shikoku come the wonderful crystals of antimonite, which form such conspicuous objects in the mineralogical cabinets of Europe." (Rein's _Japan_ and Milne in _Things Japanese_.) The above conditions suggest the presence of tertiary formations, yet only the younger groups of that formation appear to be developed. Nor is there any sign of moraines, glacier-scorings or other traces of the ice-age.

The oldest beds which have yielded fossils in any abundance belong to the Carboniferous System. The Trias proper is represented by truly marine deposits, while the Rhaetic beds contain plant remains. The Jurassic and Cretaceous beds are also in part marine and in part terrestrial. During the whole of the Mesozoic era Japan appears to have lain on or near the margin of the Asiatic continent, and the marine deposits are confined for the most part to the eastern side of the islands.

The igneous rocks occur at several geological horizons, but the great volcanic eruptions did not begin until the Tertiary period. The existing volcanoes belong to four separate arcs or chains. On the south is the arc of the Luchu islands, which penetrates into Kiu Shiu. In the centre there is the arc of the Izu-no-Shichito islands, which is continued into Hondo along the Fossa Magna. In North Hondo the great Bandai arc forms the axis of the island and stretches into Yezo (Hokkaido). Finally in the east of Yezo rise the most westerly volcanoes of the Kurile chain. The lavas and ashes ejected by these volcanoes consist of liparite, dacite, andesite and basalt.

Structurally Japan is divided into two regions by a depression (the "Fossa Magna" of Naumann) which stretches across the island of Hondo from Shimoda to Nagano. The depression is marked by a line of volcanoes, including Fuji, and is in part buried beneath the products of their eruptions. It is supposed to be due to a great fault along its western margin. South and west of the Fossa Magna the beds are thrown into folds which run approximately parallel to the general direction of the coast, and two zones may be recognized--an outer, consisting of Palaeozoic and Mesozoic beds, and an inner, consisting of Archaean and Palaeozoic rocks, with granitic intrusions. Nearly along the boundary between the two zones lie the inland seas of south Japan. Towards the Fossa Magna the folds bend northwards.

North and east of the Fossa Magna the structure is concealed, to a very large extent, by the outpourings of the volcanoes which form so marked a feature in the northern part of Hondo. But the foundation on which the volcanoes rest is exposed along the east coast of Hondo (in the Kwanto, Abukuma and Kitakami hills), and also in the island of Yezo. This foundation consists of Archean, Palaeozoic and Mesozoic beds folded together, the direction of the folds being N. by W. to S. by E., that is to say, slightly oblique to the general direction of this part of the island. Towards the Fossa Magna the folds bend sharply round until they are nearly parallel to the Fossa itself. (P. La.)

Secular Movement

It has been abundantly demonstrated by careful observations that the east coasts of Japan are slowly rising. This phenomenon was first noticed in the case of the plain on which stands the capital, Tokyo. Maps of sufficiently trustworthy accuracy show that in the 11th century Tokyo Bay penetrated much more deeply in a northern direction than it does now; the point where the city's main river (Sumida or Arakawa) enters the sea was considerably to the north of its present position, and low-lying districts, to-day thickly populated, were under water. Edmund Naumann was the discoverer of these facts, and his attention was first drawn to them by learning that an edible sea-weed, which flourishes only in salt water, is called Asakusa-nori, from the place (Asakusa) of its original provenance, which now lies some 3 m. inland. Similar phenomena were found in Sakhalin by Schmidt and on the north-east coast of the main island by Rein, and there can be little doubt that they exist at other places also. Naumann has concluded that "formerly Tokyo Bay stretched further over the whole level country of Shimosa and Hitachi and northwards as far as the plain of Kwanto extends;" that "the mountain country of Kasusa-Awa emerged from it an island, and that a current ran in a north-westerly direction between this island and the northern mountain margin of the present plain toward the north-east into the open ocean."

_Mineral Springs._--The presence of so many active volcanoes is partially compensated by a wealth of mineral springs. Since many of these thermal springs possess great medicinal value, Japan may become one of the world's favourite health-resorts. There are more than a hundred spas, some hot, some cold, which, being easily accessible and highly efficacious, are largely visited by the Japanese. The most noteworthy are as follows:--

Name of Spa. Prefecture. Quality. Temp., F°.

Arima Hiogo Salt 100 Asama Nagano Pure 111--127 Asamushi Aomori Salt 134--168 Atami Shizuoka " 131--226 Beppu Oita Carbonic Acid 109--132 Bessho Nagano Pure or Sulphurous 108--113 Dogo Ehime Pure 70--110 Hakone Kanagawa Pure, Salt or Sulphurous 98--168 Higashi-yama Fukushima Pure or Salt 117--144 Ikao Gumma Salt 111--127 Isobe " " Cold Kusatsu " Sulphurous 127--148 Nasu Tochigi Sulphurous 162--172 Noboribetsu Ishikari " 125 Shibu Nagano Salt 98--115 Chiuzenji Shizuoka Carbonate of Soda and Sulphur 114--185 Takarazuka Hiogo Carbonic Acid Cold Ureshino Saga " 230 Unzen Nagasaki Sulphurous 158--204 Wagura Ishikawa Salt 180 Yamashiro " " 165 Yunoshima Hiogo " 104--134

_Climate._--The large extension of the Japanese islands in a northerly and southerly direction causes great varieties of climate. General characteristics are hot and humid though short summers, and long, cold and clear winters. The equatorial currents produce conditions differing from those existing at corresponding latitudes on the neighbouring continent. In Kiushiu, Shikoku and the southern half of the main island, the months of July and August alone are marked by oppressive heat at the sea-level, while in elevated districts a cool and even bracing temperature may always be found, though the direct rays of the sun retain distressing power. Winter in these districts does not last more than two months, from the end of December to the beginning of March; for although the latter month is not free from frost and even snow, the balminess of spring makes itself plainly perceptible. In the northern half of the main island, in Yezo and in the Kuriles, the cold is severe during the winter, which lasts for at least four months, and snow falls sometimes to great depths. Whereas in Tokyo the number of frosty nights during a year does not average much over 60, the corresponding number in Sapporo on the north-west of Yezo is 145. But the variation of the thermometer in winter and summer being considerable--as much as 72° F. in Tokyo--the climate proves somewhat trying to persons of weak constitution. On the other hand, the mean daily variation is in general less than that in other countries having the same latitude: it is greatest in January, when it reaches 18° F., and least in July, when it barely exceeds 9° F. The monthly variation is very great in March, when it usually reaches 43° F.

Meteorology.

During the first 40 years of the _Meiji_ era numerous meteorological stations were established. Reports are constantly forwarded by telegraph to the central observatory in Tokyo, which issues daily statements of the climatic conditions during the previous twenty-four hours, as well as forecasts for the next twenty-four. The whole country is divided into districts for meteorological purposes, and storm-warnings are issued when necessary. At the most important stations observations are taken every hour; at the less important, six observations daily; and at the least important, three observations. From the record of three decades the following yearly averages of temperature are obtained:--

F°.

Taihoku (in Formosa) 71 Nagasaki (Kiushiu) 60 Kobe (Main Island) 59 Osaka (Main Island) 59 Okayama (Main Island) 58 Nagoya (Main Island) 58 Sakai (Main Island) 58 Tokyo (Capital) 57 Kioto (Main Island) 57 Niigata (Main Island) 55 Ishinomaki (Main Island) 52 Aomori (Main Island) 50 Sapporo (Yezo) 44

The following table affords data for comparing the climates of Peking, Shanghai, Hakodate, Tokyo and San Francisco:--

Mean Longitude. Latitude. Temp., F°.

Peking 116° 29´ E. 39° 57´ N. 53 Shanghai 121° 20´ E. 31° 12´ N. 59 Hakodate 140° 45´ E. 41° 46´ N. 47 Tokyo 138° 47´ E. 35° 41´ N. 57 San Francisco 122° 25´ E. 37° 48´ N. 56

Mean Temp. of Hottest Month. Hottest Month.

Peking July 80 Shanghai " 84 Hakodate August 71 Tokyo " 79 San Francisco September 63

Mean Temp. of Coldest Month. Coldest Month.

Peking January 22 Shanghai " 26 Hakodate " 28 Tokyo " 36 San Francisco " 49

Rainfall.

There are three wet seasons in Japan: the first, from the middle of April to the beginning of May; the second, from the middle of June to the beginning of July; and the third, from early in September to early in October. The dog days (_doyo_) are from the middle of July till the second half of August. September is the wettest month; January the driest. During the four months from November to February inclusive only about 18% of the whole rain for the year falls. In the district on the east of the main island the snowfall is insignificant, seldom attaining a depth of more than four or five inches and generally melting in a few days, while bright, sunny skies are usual. But in the mountainous provinces of the interior and in those along the western coast, deep snow covers the ground throughout the whole winter, and the sky is usually wrapped in a veil of clouds. These differences are due to the action of the north-westerly wind that blows over Japan from Siberia. The intervening sea being comparatively warm, this wind arrives at Japan having its temperature increased and carrying moisture which it deposits as snow on the western faces of the Japanese mountains. Crossing the mountains and descending their eastern slopes, the wind becomes less saturated and warmer, so that the formation of clouds ceases. Japan is emphatically a wet country so far as quantity of rainfall is concerned, the average for the whole country being 1570 mm. per annum. Still there are about four sunny days for every three on which rain or snow falls, the actual figures being 150 days of snow or rain and 215 days of sunshine.

Wind.

During the cold season, which begins in October and ends in April, northerly and westerly winds prevail throughout Japan. They come from the adjacent continent of Asia, and they develop considerable strength owing to the fact that there is an average difference of some 22 mm. between the atmospheric pressure (750 mm.) in the Pacific and that (772 mm.) in the Japanese islands. But during the warm season, from May to September, these conditions of atmospheric pressure are reversed, that in the Pacific rising to 767 mm. and that in Japan falling to 750 mm. Hence throughout this season the prevailing winds are light breezes from the west and south. A comparison of the force habitually developed by the wind in various parts of the islands shows that at Suttsu in Yezo the average strength is 9 metres per second, while Izuhara in the island Tsushima, Kumamoto in Kiushiu and Gifu in the east centre of the main island stand at the bottom of the list with an average wind velocity of only 2 metres. A calamitous atmospheric feature is the periodical arrival of storms called "typhoons" (Japanese _tai-fu_ or "great wind"). These have their origin, for the most part, in the China Sea, especially in the vicinity of Luzon. Their season is from June to October, but they occur in other months also, and they develop a velocity of 5 to 75 m. an hour. The meteorological record for ten years ended 1905 shows a total of 120 typhoons, being an average of 12 annually. September had 14 of these phenomena, March 11 and April 10, leaving 85 for the remaining 9 months. But only 65 out of the whole number developed disastrous force. It is particularly unfortunate that September should be the season of greatest typhoon frequency, for the earlier varieties of rice flower in that month and a heavy storm does much damage. Thus, in 1902--by no means an abnormal year--statistics show the following disasters owing to typhoons: casualties to human life, 3639; ships and boats lost, 3244; buildings destroyed wholly or partially, 695,062; land inundated, 1,071,575 acres; roads destroyed, 1236 m.; bridges washed away, 13,685; embankments broken, 705 m.; crops damaged, 8,712,655 bushels. The total loss, including cost of repairs, was estimated at nearly 3 millions sterling, which may be regarded as an annual average.