Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/629

JAVA 601 The central ridge, in which, with the single exception of Muria, all the volcanic peaks are situated, contains a large number of other summits upwards of 6000 feet in height, and several such as Wallet, Pangerangu, Merbabu, Gun- ong Butak, G. Weliran, G. Argowulan, the Yang (Jang) mountains, G. Rante rise beyond 1)000 feet. On both the north and south sides the volcanic chain is flanked by ranges composed of Tertiary rocks ; these attain an elevation on the south frequently of between 2000 and 4000 feet, and occasionally in the Preanger Regencies of 5000 or 6000 feet. To the northern flanking range belongs the whole of the island of Madura, which has its highest point in Gunong Tambuko (1541 feet). The northern versant of Java differs from the southern in the great development of its alluvial border, which in one or two places widens out into considerable plains, and from this it naturally results that the streams flowing into the Sea of Java are both in length of course and volume of water more important than those that fall into the Indian Ocean. Their number in both cases is very great ; but none even of the northern streams are navigable for vessels of burden, and only a few for boats beyond the reach of the tide. They are all more or less obstructed by mud or sandbanks at their mouths. In the Sunda lands the river names are usually introduced by Tji, the Sunda word for river ; the equiva lent Kali is prefixed less frequently to the names in the Javanese portions of the island. The largest and in some aspects the most useful of all the rivers is the Eengawan, or river of Solo, so called from Solo, the popular name of the city of Surakarta. It is in the residency of Surakarta that it takes its rise in the plain bounded by Merapi on the W., by Lawu on the E., and by Gunong Kidul on the S., and it flows through the residencies of Madiun, Rein- bang, and Surabaya. Except for the last three months of the dry season it is navigable for large boats, and during the whole year for small ones. Next in magnitude to the Solo is the Brautas, called in its lower part the Kalimas, and by Europeans the river of Surabaya Both rivers debouch into the strait of Madura, and the rapid forma tion of alluvial deposits in the neighbourhood of their mouths gives abundant proof of their disintegrating agency. In 1818 the largest vessels were able to anchor in the road stead of Surabaya; by 1825 considerable caution had to be observed ; and it speedily became evident that the northern approach would soon be completely closed. Be tween 1850 and 1854 the lower part of the Solo river was diverted into a new channel, and a permanent fairway seemed to be secured. But the condition of the strait has again been the object of solicitude, and two different schemes have been under consideration for the removal of the lower course of the river still further to the north. " All along the north coast of Java similar accretions of land are taking place ; and steam dredgers have to be kept at work in all the important harbours. The endless disturbances produced in the original con dition of the .strata by the continued activity of the volcanic forces render the task of the geologist peculiarly difficult. The volcanic rocks for the most part appear to rest on sedimentary rocks, and these in their turn are pretty certainly supported by granite and syenite. That the sedimentary rocks should all (the modern alluvium of course being excluded) be assigned to the Tertiary period was argued by Junghuhn from the fact that in spite of planting of coffee in the districts of Probolingo and Renianeh. In 1879 the Preanger Regencies were visited by several severe shocks, and a number of persons were killed. Besides the volcanoes them selves, there are a number of striking forms of volcanic activity to be observed in the island, such as the so-called mud-volcano at Grobogan, the gas-fountains or holy-fires of Melati Derat, and the Pakaraman or Guwa Upas (Valley of Poison) in Banyumas on the Dieng mountains. Hot springs are common. their difference in composition and character they all con tain the same class of fossils ; but a few striking examples of fossils and formations that must belong to the diluvial division of the Quarternary period have been pointed out by Staring and Verbeek. Throughout the rocks remains of vertebrates are exceedingly scarce ; but of invertebrates there is a great profusion. 1 In keeping with its geological structure, Java appears in general to be in the matter of economic minerals the poorest of the great islands of the archipelago. 2 Coal is very common, in thin strata and small " pockets," both in Java itself and in Madura and the lesser islands, but it has hitherto been found impossible to turn it to any consider able account. A variety of clays fit for bricks, earthen ware, and porcelain, a peculiar kind of clay (ampo) eaten as a dainty by the natives, good limestone and marble, petroleum, and sulphur have been more or less regularly worked. Salt is obtained from the mud wells of Kuwu and Solo (Saniarang), and saltpetre at Sutji in the depart ment of Gresik. Climate. Java being situated but a short distance from the equator, with the wide expanse of the Indian Ocean extending to the south, the climate is one of tropical heat and moisture. At Batavia, the only place where a long series of meteorological observations is available, the greatest maximum temperature of the air between 1866 and 1878 was 96 08 Fahr., in November 1877, and the lowest minimum 66 02, in September of the same year. The mean temperature during the same period was 78 69. Taking the monthly means we find January 77 48, February 77 52, March 78"24, April 79 34. May 79 59, June 78 83, July 78 25, August 79 14, September 79 35, October 79 50, November 79 23, December 77 86. It is this long unbroken continuity of high tem peratures which proves trying to the European constitution, for the new-corner seldom feels himself much oppressed by the heat. The maximum daily temperature occurs in January, June, and July at 2 o clock and in the other months at 1 o clock P.M. The highest maximum of barometric pressure recorded between 1866 and 1878 was 30 inches in July 1877, and the lowest minimum 29 64 inches in December 1870. In the ten years 1866-1875 the dill erence be tween the highest dail} 7 mean and the lowest was only 295 of an inch. Java is situated in the region of the south-east trade wind, and that is the prevailing direction of the wind during one, half of the year, from April to October. During the other half of the year a north-west or west wind (the physical continuation of the north-east trade wind) blows with nearly equal steadiness. The former period is known as the dry season or east monsoon, and the latter as the rainy season or the west monsoon. The distinction between the dry and the rainy seasons is most marked in the eastern portion of the island ; and indeed when we come as far west as Batavia it cannot be said that there is any part of the year altogether free from rain. During the dry season the well-known phenomenon of land and sea breezes is very distinctly exhibited; during the rainy season, through obvious causes, the alternation becomes much less regular. ] See Staring, " Sur 1 existence du terrain diluvien a Java," in Archives Neerlandaiscs, 1867, and " Voorkomen van dil. gronden op Java," in Vers. of Kon. Akad. van Wet., Afdeel. Natuurk., 1865; Verbeek, " Geologie van Java " in Tijdschr. van het Aardk. Genoot., part i. ; Lorie, Bijdrage tot de Kennis der Jav. cnqiliefyestcenten, Rotterdam, 1879; Martin, Die Tertiarschichten auf Java nach den Entdeckungen von Fr. Junghuhn, Leyden, 1879 ; " Sur les volcans de 1 ile de Java et leurs rapports avec le reseau pentagonal," in Comptes Rendus, torn. Ixxix. pp. 1058-1061. There has as yet been no regular geological survey of Java ; and much new light may be expected from the labours which the Government has at last deter mined to prosecute. From Verbeek and Fannema s " Nouv. faits geol. observes a Java," in Arch. Neerland., 1881, we learn that the exist ence of granite and other pre-Tertiary rocks, the absence of which has long been regarded as one of the cliief points of difference between Java and Sumatra, is now ascertained beyond all dispute. a See Verbeek, De Mijmretten in Ned. Ind., Batavia, 1879. xii r. -- 76