MINDANAO AND SULU : II. PHYSIOGRAPHY. 347 



work of estuaries affords easy communication by boats between the many 

 settlements on the plain. The true delta runs back as far as the junction 

 of the two main branches at Tumbao. The valley above this, for 30 

 kilometers or so, is not so wide, because the low Silik hills come down 

 fairly close to the river on the north side ; the latter then makes almost a 

 right-angled bend to the north. To the southeast of this point there is 

 a wide, low tract, 50 or 60 kilometers across, containing two bodies 

 of water, marked on the map as Lakes Liguasan and Buluan. These 

 are little more than swamps, their size varying with the rainfall. This 

 great tract is gradually draining as the land slowly rises. 3 However, 

 it could be artificially drained should this island ever become extensively 

 colonized. 



From this point to the northward the valley plain continues with 

 varying width. Some low hills appear to the northwest at the junction 

 of the Kabakan and the Eio Grande, but toward the sea there is an 

 extensive tract of low, forest-covered land without the high mountain 

 range usually shown on the old maps. This position, which is about 160 

 kilometers from the mouth of the river, is the farthest locality I reached 

 in traveling up the valley. From this point I turned off to the east, 

 following up the Kabakan Eiver. Mr. Ickis, who made the trip from 

 Cagayan, in Misamis, to Sevilla, reported extensive open country on either 

 side of the river in that vicinity. 



It seems reasonably certain that the region to the south of the Eio 

 Grande was once separated from the northern part by an arm of the sea 

 which extended from Cotabato to Sarangani Bay. The existence of raised 

 coral reefs on the south of the river points to this with a fair degree 

 of conclusiveness. The stretch of country east of Lake Liguasan is 

 underlain by loose sandstone which probably is quite recent. The rocks 

 of the Matutan Eange, a very interrupted line of volcanic stocks, are 

 andesites which have poured over the country in rather recent times. 



The largest settlements of the Maguindanao Moros are to be found at 

 the lower end of the Grande Eiver plain. Cotabato, a town of about 

 1,000 civilized 4 inhabitants is situated about 10 kilometers, by river, 

 from the mouth. Although Cotabato is behind both Zamboanga and 

 Davao at the present time, it has in some respects a more favorable 

 geographic situation than either. Any town situated at the mouth of a 

 navigable river draining an interior like that of central Mindanao pos- 

 sesses great advantages over those which are not so situated; and, there- 

 fore, if Mindanao is ever opened to colonizers, Cotabato should become 

 the metropolis. 



3 The evidences for very recent and very considerable elevation in Mindanao 

 are abundant. 



* Philippine Census ( 1903) . 

 99514 4 



