218 COMPENDIUM OF GEOGRAPHY AND TRAVEL 



interior. In the beginning of the Diluvial period these 

 gulfs began slowly to give place to dry land ; a strip of 

 flat land was formed along the foot of the mountains, and 

 gold, diamonds, and platinum, swept down by running 

 water, were here deposited. The seas became shallower 

 and retreated, and the present period commenced." 



From the above sketch, the general configuration of 

 Borneo of the present time can be gathered. We find a 

 skeleton mountain formation in which the mountains, 

 although arranged in chains, are not continuously elevated, 

 but more or less separate and insular in nature ; a hill- 

 land of Tertiary age surrounding it, and in turn bordered 

 by a dry plain land, which merges imperceptibly into 

 vast swamps and morasses, through which large and tor- 

 tuous rivers find their way to a shallow sea. This rough 

 outline does not, of course, hold equally good for all 

 localities. Thus in British North Borneo the land is 

 more elevated, and the older rocks in close approxima- 

 tion to the sea, and the formation in Brunei and in the 

 western promontory of the island is likewise irregular. 

 It is in the southern and eastern portions that the char- 

 acters mentioned are most apparent. Here we have four 

 main basins, drained principally by the Kapuas, Barito, 

 Koti, and Kayan rivers, and separated from each other 

 by mountain chains. 



The Tertiary beds of which the hill and lower lands 

 are composed have been separated into Eocene, Oligocene, 

 and Miocene. Dr. Posewitz states that " all four stages 

 of the Eocene are developed in Borneo. The first or 

 breccia stage, consisting of conglomerates and sandstones, 

 is up to the present only known in West Borneo. The 

 second, or sandstone stage, is of great thickness and wide 

 development ; it yields the Indian coal, and consists of 

 quartz, sandstones, shales, and coal seams. The third, or 



