



PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



GEOLOGICAL SOCIETY OF WASHINGTON 



The 258th meeting was held May 8, 1912, President Stanton in the 

 chair. The following informal communication was presented: The 

 General Custer Vein in Idaho, J. B. Umpleby. 



REGULAR PROGRAM 



Some phases of Philippine geology (illustrated by lantern slides) : War- 

 ren D. Smith, Chief of Division of Mines, Philippine Islands. For 

 our present knowledge of the geology of the Philippine Islands we are 

 indebted chiefly to four men — Abella, former chief of the Spanish Mining 

 Bureau; Becker, first American geologist to visit the islands; McCaskey, 

 the second chief of the American Mining Bureau, and Iddings, who has 

 worked on Philippine rocks and who visited the islands in 1910. The 

 igneous rocks are mainly diorite, representing the plutonic type, and 

 pyroxene andesite the extrusive type. Leucite-bearing rocks have been 

 found in one locality, Masbate, but this is an unusual development. 

 Metamorphic rocks are represented by schists and gneisses, which are 

 probably metamorphosed sedimentary and igneous formations of Ter- 

 tiary or Mesozoic age. Of the sedimentary rocks there are none that 

 we know positively to be older than Eocene. Most of the sediments 

 are Miocene and later. Coral and orbit oidal limestones are wide-spread. 

 Some red cherts containing uncertain fragments of sponges and radiolaria, 

 and possibly to be correlated with similar material of Jurassic age in the 

 Moluccas have been found in northern Luzon. 



Coal, oil, iron, gold and copper are the principal economic deposits of 

 the islands. Coal of a sub-bituminous grade, in which the fixed carbon 

 is usually less than 50 per cent, is widespread. One seam 1| feet thick 

 having 82 per cent of fixed carbon has been found in Mindanao. What 

 appear to be large deposits of bessemer iron ore exist in Luzon, and pig- 

 iron is being produced by crude processes by the natives. A long-known 

 and fairly good deposit of copper ore (largely enargite) occurs in northern 

 Luzon, but fuel and transportation difficulties delay development. A 

 deposit of the native metal exists in Masbate, but this is also undevel- 

 oped. There are several stamp mills and gold dredges operating now 

 in the islands and the industry has a bright future. Oil seepages to the 

 number of at least half a dozen have been found on Cebu, Leyte, and 

 Tayabas Peninsula, some of the oil being paraffin oil of light gravity. 

 The possibility of the existence of commercial quantities has not been 

 tested. 



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