SUBMERGED PLATFORMS OF THE PHILTPPINES 521 



Barrier of Australia. Hence not only does the absence of shore cliffs in 

 the Philippines testify against the abrasion of platforniS;, on which so 

 much weight is laid in the Glacial-control theory, but the submergences 

 of different members of the Philippine group by different amounts and -at 

 different dates testify to local subsidences and not merely to a universal 

 rise of ocean level. 



THE SUBMERGED PLATFORMS OF THE PHILIPPINES 



In view of the absence of shore cliffs, the submarine platforms w^hich 

 are to be expected in association with new fringing reefs, and which are 

 well developed in certain parts, but not in all parts, of the Philippines, 

 and which, furthermore, are sometimes imperfectly rimmed by reefs that 

 do not reach the sea surface, may as above noted be much better explained 

 as submerged and more or less aggraded reef plains than as abraded plat- 

 forms cut on still-standing islands when the ocean was lowered in the 

 Glacial period. The intermittent development and the varying depths 

 of the platforms are strongly confirmatory of this view. For example, 

 the long island of Palawan, which stretches 300 miles southwestward 

 toward Borneo, is surrounded by an extensive submarine platform with a 

 width of some 30 miles along the northwestern coast, where it is imper- 

 fectly rimmed by a discontinuous marginal reef that rises to depths of 

 10 or 20 fathoms. Opposite the middle of the island the platform sinks 

 to depths of 50 or 60 fathoms, which is greater than can be accounted for 

 by the Glacial-control theory; this part of the island coast is extraordi- 

 narily embayed, fringing reefs are almost wanting, and delta flats are 

 small. If observation on the ground should discover signs of a moderate 

 emergence along this part of the coast of later date than that of the. sub- 

 mergence to which the embayments are due, then the submergence must 

 have been for a time even greater than it is now. Farther south, in the 

 neighborhood of Balabac Island, between Palav^an and Borneo, the plat- 

 form has a depth of only 25 or 30 fathoms, many isolated reef patches 

 reach the sea surface, and the shore of Balabac has fringing reefs from 

 two to three miles wide. Farther north a large part of the island of 

 Luzon has a comparatively simple shoreline and no submerged platform ; 

 the lowland plains of this island seem to be the physiograpliic contem- 

 poraries of the submerged platform of Palawan. 



These unlike features of the Philippines are much better explained by 

 subsidence, varying in date, rate, place, and amount, than by any other 

 process: northern Luzon seems to have stood almost stationary, while 

 Palawan was downwarped. The frequent recurrence of depths of about 

 40 fathoms on the margin of many submerged platforms is, like the depth 



