164 SPAKKS FEOM A GEOLOGIST'S HAMMER. 



are mostly but the higher eminences of an ancient prolon- 

 gation of the Asiatic continent that has been sunken by 

 volcanic action or wasted by the agencies of erosion. 

 Southeast of the Indo-Chinese peninsula there are no 

 soundings until we reach the line connecting Celebes with 

 Java. This is a distance of twelve hundred miles from 

 the mouth of the Cambodia river. The width of these 

 shallow soundings is seven hundred miles. From Java the 

 zone of shallow soundings extends north-northeast to a 

 point beyond Luzon, a distance of about two thousand 

 miles. Now, all around through Sumatra and Java to 

 Mindinao and the Philippines is a chain of active and ex- 

 tinct volcanoes from whose craters incalculable volumes 

 of molten matter have been ejected, even during the his- 

 toric period of our race. The island of Java alone is the 

 site of forty-seven of these volcanic vents. To supply erup- 

 tions of such magnitude has undermined the solid crust 

 throughout all the neighboring region. The southern 

 angle of the continent has sunken till its valleys lie from 

 fifty to one hundred fathoms below the level of the sea, 

 while its mountains stand even up to the chin in water. 

 The sunken area is four thousand miles in length from 

 east to west, and thirteen hundred in breadth from north 

 to south. 



This subsidence, accelerated by atmospheric and oceanic 

 erosions, has taken place during the modern epoch of geo- 

 logical history. Not only birds and insects, but reptiles 

 and ponderous quadrupeds, that once had liberty to range 

 over the continental surface, are now restricted to isolated 

 islands, whose limits are even yet becoming narrower. 

 The eastern portion of the Malay archipelago, however, 

 is separated from the western by a deep ocean channel. 



