356 SMITH. 



1903, was 3,165 millimeters. This was exceeded in only two other places 

 in the Philippines, namely, at Borongan, east coast of Samar, and Ma- 

 sinloc, west coast of Luzon. 



Prom the fragmentary notes we have on this portion of the country I 

 infer that the rocks of this cordillera are much the same as those in the 

 cordillera of Luzon. I do not expect to find the rocks of Mindanao any 

 older than those of other parts of the Islands, but possibly somewhat 

 younger. 



Figure 4 gives a provisional idea of the main tectonic lines, to which 

 is added the hydrography as we now know it. 



LAKES. 



There are in all thirteen lakes known in Mindanao. In order of size 

 they are: Lanao, Liguasan, Buluan, Linao, Mainit, Kadagan, Malanao, 

 Leonard Wood, Balut, Dapao, Butig, and Munay. 



Lake Lanao. — This has already been referred to under another head. 



Lakes Liguasan and Buluan are simply the remnants of a greater 

 body of water which formerly occupied all the central low country. 

 Lieutenant Van Horn, United States Army, made an exploring .trip 

 in 1902 from Cotabato across the Tiruray table-land to Makar and 

 back by way of the valley between Mounts Malibatu and Matutan. He 

 was of the opinion that the Eio Grande once flowed through Lakes 

 Liguasan and Buluan along the depression now followed by the trail 

 through Talik and Tambatu. This, I think, is very probably correct. 

 These lakes are very shallow, being little more than swamps. Lieutenant 

 Van Horn in his manuscript report to the Adjutant-General says : 10 



Our route was through the Buluan Eiver connecting the two lakes. The 

 entrance to the river from lake Buluan was not more than a meter wide on 

 account of being choked up by floating islands of grass, but it widened out to 

 about forty meters for about 5 kilometers. It was hard to distinguish the river 

 from the numerous esteros. After 7 kilometers we came to some solid ground 

 on the left bank where there was a tiangi or market. After this we could see 

 no solid ground on either bank until I reached the Rio Grande. Buluan river 

 is very swift, so swift in the channel we came down that vintas must go up by 

 another route. In one place we passed over a small fall about three-quarters of 

 a meter in height, the turn and the bottom being very sharp and we going so 

 fast that our vinta was forced through the high grass on the bank about 9 meters. 

 Entered Lake Liguasan about 1 P. M. The lake was very much the same as 

 the surrounding country, a few patches of open water, large floating islands, 

 and the rest covered with lily pads and water cabbages. A small channel 

 was made by boats cutting their way through. The character of the lake changes 

 with every wind. 



Lakes Linao and Kadagan. — These two lakes are not much more 

 than marshy areas where the Agusan Eivef has spread out over a large 

 tract of low ground. There are three lakes marked on the latest map 



10 Van Horn, Lieut. E. C. MS. Report to Adjutant-General, United States 

 Army, Philippines Division, January, 1902. 



