JAVA 
113 
Besides the true volcanoes there are many hill ranges 
and lesser mountains in Java; and skirting the southern 
shore there is a great range of low mountains about 3000 
feet in height, formed of basalt, trap, and sometimes of 
limestone. . This latter appears to be of Miocene age, as 
it contains shells and corals allied to those of the 
European Miocene, as well as others similar to those 
which now live in Eastern seas, three out of twenty-two 
being living species. 
The rivers of Java, especially on the north side, are 
almost innumerable, but from the form of the island 
they are of comparatively small size, and a few only 
are navigable for boats. Their rapid flow and perennial 
supply of water are excellently adapted for irrigation, to 
the practice of which much of the fertility of the country 
is due. The largest and most useful river of the island 
is that usually called the Solo Biver, from its passing the 
native capital of that name. It has its source in one of 
the low ranges of hills towards the southern side of the 
island, and after a tortuous course of 310 miles empties 
itself into the sea by two mouths opposite the western 
end of Madura. Except for three months, from August 
to October, it is navigable by large boats, and at all times 
by small ones. It would even be accessible to ocean 
vessels but for the bar at its mouth. The next largest 
river is the Brantas, or river of Surabaya. This also 
rises near the southern coast, on the west side of the 
Semeru mountain, and after receiving many affluents, 
enters the sea by two mouths, one of which passes the 
town of Surabaya and contributes to form its harbour. 
In the west of Java the Chi Tarum (Chi, or Tji as it is 
usually written, being the Sundanese word for river) and 
the Chi Manuk are the most important rivers, but they 
