23,1 Merrill: Distribution of Dipterocarpaceae 13 



great continental shelves) , is the presence of great development 

 during Pleistocene times in the intermediate stress area of very 

 notable marine deeps and corresponding upthrust island masses. 



In the Philippines there is strong suggestive evidence that 

 some of our deeps, such as those connected with the Formosan and 

 Mindanao Rift systems, were formed and reformed repeatedly 

 during the Tertiary. There is even stronger evidence to show 

 that the Formosan Rift originated in the Tertiary and that move- 

 ments along this great rift during that time have maintained a 

 constant separation between Formosa and the Philippines. 

 Doctor Dickerson concludes, from a study of the Malumbang 

 strata, which is widely distributed in the Philippines, that only 

 shallow seas existed in the Philippines during the Pliocene. In 

 the Philippines the earliest geologic formations that have been 

 recognized are the Jurassic of the early Mesozoic. The Creta- 

 ceous, the Eocene, and the Oligocene formations are absent in 

 the Philippines, or at least have not been recognized by geolo- 

 gists, so far as geologic exploration of the Archipelago has 

 progressed. 



Molengraaff's 15 concise summary of our present knowledge 

 of the land and sea areas in the Malaysian region gives us the 

 clue to the cause of the biological differences between eastern 

 and western Malaysia. His very definite conclusions cannot be 

 ignored by any student of the distribution of the flora and fauna 

 of this region. 



In the Asiatic-Australian region there have been two definite 

 continental platforms now delimited by the Asiatic and the 

 Australian continental shelves, and since the early Tertiary 

 these have been separated by an area which has been constantly 

 in an archipelagic condition. The 200-meter line may be con- 

 veniently taken as delimiting these continental shelves, but the 

 average depth of the water on these shelves is only 60 meters. 

 The Asiatic shelf carries upon it all the Sunda Islands, Sumatra, 

 Java, Borneo, and the intervening smaller islands; the Austra- 

 lian shelf carries upon it the great island of New Guinea. In 

 the Pleistocene and, probably, in the immediately preceding 

 epoch Sumatra, Borneo, Java, and the islands eastward of Java 

 to and including Bali, as well as the Balabac-Palawan-Calamian 

 group in the Philippines and probably the Sulu Archipelago, 

 were connected at times with the Asiatic continent via Borneo, 

 and New Guinea was connected with Australia. 



research in the East Indian 



