362 me. J. b. scrivenor on the [June 1913^ 



XIII. Tertiary and Recent Changes in the Peninsula. 



Erom the evidence in the Archipelago of the existence of Eocene 

 rocks, some containing granite-pebbles, we must conclude that, after 

 the granite had solidified, rapid denudation of superincumbent 

 deposits (which have now disappeared entirely) brought the granite 

 and the rocks of the two antielinoria to light. The only record of 

 Tertiary deposits known so far in the Peninsula is- afforded by the 

 Coal Measures in Selangor ; these may be Miocene, and of them 

 I need say no more now. 



Biological evidence, as shown by Dr. A. R. Wallace in ' Island 

 Life-' 1880 (p. 362), points to the Peninsula and Archipelago having 

 formed one mass of land during some part of the Tertiary Era, 

 and the shallowness of the sea which surrounds the islands of the 

 Archipelago, and borders the Peninsula and Siam, shows that no 

 very great elevation would be required to restore these conditions 

 as far as the Straits of Macassar, between Borneo and Celebes. In 

 the Peninsula itself, however, there is evidence that a period of 

 elevation is now actually in progress. This evidence is the existence 

 of old sea-beaches inland. One well-preserved beach can be seen 

 at the foot of Gunong Geriang, near Alor Star ; another in the flat 

 country between Telok Anson and the sea. But more than this, 

 there is evidence showing that the Peninsula, not so very long ago, 

 was itself an island, or group of islands, formed of what are now 

 the mountain-ranges. The low country to the west of the Kedah- 

 Singgora Range, without an) r important stream, can only be 

 regarded as a plain of marine denudation. The Kedah River 

 comes down from the hills that once formed part of the island 

 or island-group. Better evidence than this is that adduced by 

 Mr. H. N. Ridley, who shows that the difference between the pre- 

 sent floras of Lower Siam and the Peninsula south of Kedah Peak 

 is sufficient to suggest that the latter was separated by sea from 

 the land on the north. 1 



This combined geological and botanical evidence adds an 

 interesting chapter to the history of this part of the world, of which 

 we have not yet seen the end. After the destruction by sub- 

 mergence of the land-connexions that allowed the faunas of Borneo, 

 Java, and Sumatra to migrate from the north, the subsidence con- 

 tinued until the Peninsula became an island. Subsidence then 

 gave place to elevation, the Peninsula came into being again, and 

 there is 1 in progress a gradual approach to the old conditions of an 

 united Peninsula and Archipelago. 2 



1 H. N. Ridley, 'An Account of a Botanical Expedition to Lower Siain ' 

 Journ. Straits Branch Asiat. Sue. No. 59 (Aug. 1911) pp. 29, 30. 



2 In the paper on 'The Geology & Mining Industries of UluPahang' I 

 have endeavoured to put forward an explanation for the course of the Pahang 

 River. As may be seen from the sketch-map accompanying that paper, the 

 Pahang River suddenly turns at right angles, and flows through the Main 

 Gondwana Outcrop. The suggested explanation is that the Pahang River once 

 flowed on southwards, and emptied itself into the Straits of Malacca near the 

 month of the present Muar River, in Johore, but was captured by a small 

 river that cut back through the Main Gondwana Outcrop {pp. cit. pp. 7-9). 



