162 AUSTEALASIA. 



crater, is encircled by a diadem of lofty peaks, such as the Raun (11,000 feet) on 

 the south-west, Kendeng on the north-west, Kukusan on the north-east, Merapi 

 and others on the south-east, often collectively known as the Gunong Ijen, or 

 " Isolated Mountain." The waters that collect on this plateau were formerly 

 confined in a lacustrine basin, but now escape northwards through a gorge 

 between Kendeng and Kukusan. The crater of Raun at the time of Junghuhn's 

 visit had a circuit of about three miles and a depth of no less than 2,400 feet, 

 being the deepest of any yet explored in Java. But all these encircling volcanoes 

 are now extinct or quiescent except Merapi, whose crater, like that of Kelut, is 

 flooded by a freshwater lake, which, during eruptions, is changed to steam and 

 precipitated in the same way on the surrounding district. During the outburst of 

 1817, houses and inhabitants were swept away, and the strait flowing between 

 Java and Bali contracted by the formation of new land. The south-eastern head- 

 land of Java, formerly an island, has thus been joined to the mainland by showers 

 of scoriae, while the extinct Baluran (4,300 feet), at the north-east extremity, is 

 separated only by a sill 50 feet high from the Gunong Ijen sj^stem. 



The island of Madura, close to the north coast, has a somewhat irregular 

 surface of limestone rocks, the highest of which, Tambuku, at the east end, has an 

 elevation of little over 1,500 feet. As in Java itself, Yerbeek's survey shows that 

 in Madura there is no trace of triassic, Jurassic, or chalk formations. 



Although the igneous are far less extensive than the sedimentary rocks in Java, 

 this island receives its characteristic aspect from its forty-five consj^icuous volcanoes 

 with their lateral cones, lavas, and scoriae. As the mariner approaches its shores, 

 his gaze is irresistibly attracted by these lofty symmetrical cones, towering above 

 the wooded plains, now purpled in the solar rays, now of a pale blue, standing out 

 against the deeper azure of the sky, at times surmounted by a wreath of white 

 vapours, at sunset flushed with pink like the snowy Alpine peaks. At different 

 epochs, but especially during later tertiary times, all these burning mountains 

 have taken part in the transformation of the island ; even during the historic 

 period more than twenty of them have contributed greatly to modify the profile 

 and contours of the land, transforming what was before a chain of separate 

 islands, like the Lesser Sundas, into one continuous insular mass stretching from 

 Bali to Sumatra. This action of the underground agencies appears also to have 

 been aided by a process of slow upheaval, which is still going on ; in many places, 

 the beach and coral reefs have thus been raised twenty, thirty, and even fifty feet 

 above the present sea-level. 



Rivers of Java. 



Owing to the position of the volcanic ranges, lying for the most part much 

 nearer to the Indian Ocean than to the inland seas, the northern are far more 

 extensive than the southern fluvial basins, scarcely any of which are navigable. 

 The north-western plains about Batavia are watered by numerous streams, the 

 largest of which is the Tarum, which rises on the slopes of the southern volcanoes, 



