CONFIGURATION OF THE ARCHIPELAGO 52l 



far from 45 degrees to the vertical. Extending southwest and at abont 

 right angles to this line are the two long arms of the Palawan-Cnyo-Min- 

 doro gronp. South of this and parallel to it, but separated by a consid- 

 erable stretch of sea, is the Sulu chain. The long axes of these groups 

 have a northeast-southwest direction. 



On the north we have the largest single land-mass, the island of Lu- 

 zon; in the middle a larger number of much smaller islands, and to the 

 south the second largest and more compact land-mass, the island of 

 Mindanao. 



A glance at a map of the archipelago will impress one with the most 

 important single physiographic feature in connection with the whole 

 archipelago, namely, the enormous length of coastline — 11,511 miles in 

 extent. This is due in part to the submergence of dissected islands — a 

 condition of the whole land-mass comprising the archipelago. In addi- 

 tion to the great number of small islands, we find the larger islands lib- 

 erally supplied with indentations of varying size, all of which increase 

 the length of coastline proportionally. 



It has appeared to the writer that there has been an elevation of the 

 west side of the archipelago and a corresponding sinking of the coast on 

 the east, both of which still are persisting. This belief is borne out by 

 the raised beaches and coral reefs in places on the west coast of Lu2on, 

 the generally shallow condition of the mouths of the rivers debouching 

 west, and by the presence of drowned rivers on the east coast — notably 

 the Paracale Eiver. As yet sufficient time has not elapsed, since accurate 

 measurements have been made along the coast to enable us to say very 

 definitely whether there has been much vertical movement, nor how much, 

 nor in what direction. E. E. Frisbie, of the United States Coast and 

 Geodetic Survey office in Manila, has noted a probable subsidence of the 

 coast at Manila amounting to .31 foot in nine years. ^ United States 

 Army engineers at Corregidor noted a slight elevation during a part of 

 this period. Aside from the differential movement, there undoubtedly 

 has been a general subsidence at times of the whole archipelago.^ That 

 there has been a corresponding and a very general elevation is borne out 

 by the finding of fossil specimens of lowland vegetation at an elevation 

 of 5,000 feet in north central Luzon. 



It is the writer's belief that deeper water prevails on the eastern coast- 

 line than on the western. That this certainly is true a little distance out 

 from the land is shown by the soundings of the German survey ship 



2E. R. Frisbie: Proceedings of Philippine Society of Engineers, Manila, 1911, p. 36. 

 3 Fragments of corals have been brought in drill cores in the Batan coal fields from 

 mucb greater depths than corals are accustomed to grow. 



