126 AUSTEALASIA. 



Several of the summits in Central Borneo consist of granite and other crystal- 

 line rocks, as sufficiently attested by the débris Avashcd down and strewn over the 

 plains by the running waters. But in the regions near the seaboard nearly all 

 the hills are of sedimentary formation. Of these the calcareous rocks are very 

 prevalent, their innumerable caverns affording shelter to myriads of the esculent 

 swallow. Other deposits of various ages contain rich beds of coal and lignite, 

 and man}' parts of the island abound in thermal springs. Although surrounded 

 by a semicircle of igneous islands, Borneo appears at present to contain no active 

 volcanic centres ; but this region also had at one time its eruptive craters, and 

 the scoriae and other traces of extinct fires may still be seen here and there, as in 

 the neighbourhood of Kina-Balu and in the Montrado uplands. 



The outlines of the Bornean seaboard have frequently been modified. If there 

 was a time when it formed continuous land with Sumatra and the Malay peninsula, 

 it was also at other epochs reduced to the mere skeleton of its mountain ranges, 

 destitute of the argillaceous, shingly, and alluvial plains at present filling up the 

 spaces between its divergent chains. It was probably during these epochs that its 

 volcanic cones blazed above the neighbouring marine waters. Then also were 

 deposited the horizontal beds on which are strewn the ferruginous pebbles washed 

 down from the hills, and among which are collected the precious metals, gold, 

 platinum, quicksilver, as well as diamonds of the purest water. Gold washings 

 occur in most provinces— the British territory in the north, Sarawak, Montrado, 

 the Pontianak and Banjermassin district. The Malays and Dayaks are moreover 

 acquainted wdth numerous mineral deposits, which they jealously conceal, either in 

 the hope of retaining a monopoly of the mines or else in order to keep the for- 

 eigners from their territory. The diamond mines are usually found in pockets 

 of argillaceous soil at some distance from the auriferous beds. 



Rivers of Borneo. 



Thanks to an abundant rainfall, Borneo is watered by a considerable number of 

 broad streams flowing in all directions seawards. Nevertheless the north-west 

 slope between the main range and the coast is too narrow for the development of 

 any great watercourses. Here the most copious is the Brunei, or Borneo, which 

 falls into the estuary at the capital of the state of like name. Farther south, but on 

 the same north-west slope of the island, are the navigable rivers Rajang and 

 Lupar, besides the Sarawak, which, although of small size, is better known from 

 the town of that name situated on its estuary, the scene of so many stirring events 

 in recent years. 



One of the three largest rivers in Borneo is the Kapuas, whose catchment 

 basin lies between the two south-western mountain ranges, and which flows mainly 

 towards the south-west. The chain of large lakes which formerly marked its course 

 have been gradually filled in by alluvial deposits, and are now î-epresented only by 

 so-called danaus, such as the Sriang and Luar, periodically flooded shallow lagoons 

 occurring at intervals along the riverain plains. Before reaching the low-lying 



