234 The Philippine Journal of Science i9i6 



An unnamed lake about equal in size to Lake Leonard Wood 

 is shown upon several maps of Mindanao near the head of Tagun 

 River in Davao district, east-central Mindanao. The surround- 

 ing country is unexplored, and no details concerning the lake 

 are available. 



Lakes Munay, Dapao, and Nonugan are small bodies of water 

 in the vicinity of Lake Lanao. Lake Munay has an area of 

 1 square kilometer and lies at an elevation of 700 meters; 

 Lake Dapao has an area of 2 square kilometers and is 628 

 meters above sea level; Lake Nonugan has an area of 1 

 square kilometer and is 768 meters above sea level. According 

 to Smith these lakes occupy local depressions on the surface of 

 the basalt flows which cover the region in which they are found. 



Smith observed two lakes, Malanao and Balut, near Cotabato 

 and another, Lake Butig, in southeastern Davao, each of which 

 seemed to him to occupy structural valleys, or synclines, in the 

 locally folded sedimentary rocks. While these lakes are small 

 and unimportant, they are worthy of note because of the unique 

 origin ascribed to them. Nowhere else in the Philippines have 

 lakes resulted from the folding of the bedded rocks. 



A small lake called Majubdam was encountered by Father San- 

 chez on the slopes of Mount Maniayao above and to the north 

 of Lake Mainit; its area is 0.1 square kilometer. 



LAKES OP MINDORO 



Lake Naujan, near the northeastern coast of Mindoro, is the 

 only known lake on this incompletely explored island. Lake 

 Naujan covers an area of about 70 square kilometers ; in outline 

 it is elongated from north to south, its surface dimensions being 

 7 by 14 kilometers. The Director of the Coast and Geodetic Sur- 

 vey estimates its elevation as 20 meters above sea level and its 

 greatest depth as 15 meters. The outlet is to the north through 

 Lumangbayan River. No large stream flows into the lake. 



Lake Naujan is probably related in its origin to volcanic 

 activity, although it does not appear to be a crater lake. The 

 eastern shore is precipitous, but to the west the land rises grad- 

 ually through vegetation-covered shallow water and swamps. 

 The outlet has cut a fairly deep valley around the base of a hill 

 which is probably of volcanic origin. Mr. A. L. Day, who spent 

 a season on Lake Naujan collecting zoological specimens, found 

 a number of hot springs and other evidences of solfatarism on 

 its eastern margin. 



