Vol. 69.] GEOLOGICAL HISTORY OF THE MALAY PENINSULA. 357 



namely, that of the Gondwana coast-line advancing from 

 west to east, has been adopted, in order to explain the occurrence 

 of the glacial rocks in Perak and the Rhaetic horizon in Pahang. 

 It will be interesting to see how far future work supports it. 



XI. The Growth of the Malay Peninsula. 



Starting from the late Palasozoic climatic horizon given by the 

 glacial rocks, one can now form some idea of the history of this 

 part of the globe. The time was that which saw the beginning 

 of the Productus deposits of the Salt Range and the beginning of 

 the Gondwana System in Peninsular India. Prior to the advent of 

 glacial conditions, the site of the Malay Peninsula had been covered 

 by a sea in which calcareous deposits (the Raub Series) were being 

 laid down. These may have been in part time-equivalents of the 

 beds which underlie the boulder-beds in the trans-Indus section of 

 the Salt Range. But for this possibility they must be regarded as 

 older than the Productus Beds. Submarine eruptions had occurred 

 over part of the floor of this sea, and were continued into later 

 times. 



The advent of glacial conditions coincided with the advance of 

 the coast-line of Gondwanaland to the site of the Malay Peninsula. 

 The constitution of the glacial deposits gives some idea of the 

 surface of this portion of Gondwanaland. It was partly formed of 

 stanniferous granitic rocks (the Palasozoic Granite), tourmaline- 

 granite being common, and of rocks metamorphosed by the Palaeozoic 

 granite-magma. Some of the rocks forming this part of Gondwana- 

 land evidently held quantities of corundum, both as pure massive 

 corundum (now found as boulders), and as granular corundum in 

 the tourmaline-corundum rocks of Kinta. 



The glacial deposits were succeeded by tho littoral Malayan 

 Gondwana rocks, deposited as the coast-line moved slowly eastwards 

 until, at the least, Rhaetic times were reached. 



Then the record is broken, until the intrusion of the Mesozoic 

 Granite in late Mesozoic times ; and the intrusion of this granite 

 was made possible by earth-movements which gave rise to the 

 present main structural features of the Peninsula. 



Most of the literature dealing with the Peninsula mentions the 

 great granitic axis, and it would not be surprising to find that this 

 axis is regarded as the dominant structural feature. The key to 

 the structure, however, is found, not in any granitic range, but in 

 the Main Range Poothills of Pahang, built up of Gondwana rocks. 

 This range of foothills is composed of the eastern limb of one 

 great anticline and the western limb of another. The one is the 

 Main Range Anticline, the other the Benom Anticline, and they 

 are the framework of the Peninsula : although it is evident that, on 

 both sides of the country, less notable disturbances have admitted 

 smaller granite-intrusions. 



The Main Range Anticline has been studied in detail in Perak and 

 Pahang. It should strictly be described as a shattered anticlinorium, 



