﻿236 " smith. 



More than one geologist 4 who has made studies along the great Pacific 

 arc has remarked upon the striking similarity existing in the geology 

 along all its points in California, Alaska, Japan and the Philippines. 



A member of the United States Geological Survey, one who has had 

 abundant opportunity to study the geology both of western America and 

 portions of Asia, writes to me as follows : 



Although the Pacific lies between and seems to separate you from the more 

 familiar phases of the geology of North America, I am of the opinion that 

 geologically you are more in touch with our western coast than the man who 

 is studying the geology of the eastern United States. The ocean basins are the 

 sources of the great dynamic effects which characterize the continental margins, 

 and there is more likeness between the opposing shores of the Pacific than there 

 is between the opposite sides of the continents. I have been interested in the 

 course of my work to find that the geology of California is the geology of central 

 China, and that there is a close likeness even in the character and date of mineral 

 deposits between our Western Cordillera and the East Indies. These similarities 

 in geologic history, in orogeny, in vulcanism, and even in mineralization are too 

 close and too long continued to be fortuitous. We shall reach an understanding 

 best by regarding the ocean as the center and the continental region as the periph- 

 ery, and by recognizing that the major phenomena differ when we cross the 

 periphery from the sphere of activity of one ocean to that of another. 



I must say, after attempting to make use of the quantitative clas- 

 sification, that it is not well adapted to our Philippine rocks. I believe 

 that in their almost universal condition of decomposition here, classifying 

 them after this manner would only be misleading. It does not seem 

 justifiable, at least in many cases, to employ a system which neglects the 

 actual mineral composition and uses an altogether arbitrary standard 

 or norm. 



The papers by Mr. Eveland and myself, then, only serve as an intro- 

 duction to this region. There are many questions which we have thought 

 over and upon which we have gathered some notes, but the time is not 

 ripe for the close study which they demand for their solution. Some of 

 these are: 



1. Relation of the period of vulcanism to the deposition of the ores. 



2. Relation of the vulcanism to the physiography. 



3. Relation of amount of ejecta to elevation and subsidence. 



4. The probability of past glaciation in the highlands of north central 

 Luzon. 



In this connection I may state that there are many features, such 

 as boulders and boulder-clay, strongly resembling moraines; ponded 

 drainage; peculiarly rounded and veneered hills; valley trains, etc., 

 which have not received full treatment in the foregoing paper of this 

 number for several reasons, the chief among these being the incom- 

 pleteness of the evidence. Markings suggestive of glacial striae have been 



4 Becker, G. F. : Geology of the Philippine Islands — Extract. 21st. An. Rept. 

 V. 8. G. S. (1902), 518. 



