58 ADAMS. 



contents — continued. 



Mineral resources — Continued. 



Stone. 



Guadalupe and Meycauayan 



stone. 



Sisiman andesite. 



Basalt. 



Prospects in the Loboo Moun- j , , 



. Gabbro. 



Limestone. 



Mineral resources. 

 Iron. 



Lanatin iron deposits. 



Iron deposits near Santa Inez 

 Copper. 



tains. 



Prospects on the Lanatin River, j Cravel 



GokL Sand. 



Coal. Clay and clay products. 



Bulacan coal field. Salt. 



Gas. Lime. 



INTRODUCTION. 



The area discussed in this report has been visited in part by nearly all 

 of the geologists who have studied the Philippine Islands since it includes 

 Manila, the capital and principal port, and a convenient starting point 

 for excursions. However, no systematic reconnaissance has been made 

 previous to this report, and the literature, which is in several languages, 

 is largely fragmentary and not readily accessible. 



The most important geologic map published is by Von Drasche, who 

 saw a considerable part of the country and drew upon the writings of 

 others and probably used data furnished him by residents of the island. 

 In addition there is a small map of Mount Maquiling by Abella and a 

 partial mapping of the tuff deposits by Centeno. 



The present reconnaissance was planned so as to make . possible the 

 correlations of the many observations of previous workers and the pub- 

 lishing of a map to serve as a guide to the understanding of the broader 

 geologic problems. The localities described by former writers have been 

 revisited with the exception of some lately studied by the members of the 

 present division of mines. 



It is to be regretted that the uninhabited and heavily wooded portion 

 of the eastern cordillera must be left unexplored, and that many in- 

 teresting areas could not be studied more in detail because the general 

 problems required all the allotted time. 



Aside from the purely scientific interest, the reasons for making this 

 reconnaissance were the need for more accurate knowledge in regard to 

 the coal deposits near Manila, the availability of structural materials 

 required in the economic development of the island, and a better under- 

 standing of the geologic conditions governing the occurrence of artesian 

 and deep-seated waters which are so necessary for the well-being of the 

 inhabitants. Large sums of money are being spent for public improve- 

 ments in this area by the Government under the direction of the Bureau 



