ILLUSTRATIONS. 



Plate I. 



Metamorphosed porphyritic rock, showing outlines of feldspars which have been 

 replaced by secondary silica. (Photomicrograph by Martin.) 



Plate II. 



Characteristic topography in the Benguet district. (Photograph by Photo 

 Supply Ck).) 



Plate III. 



Geologic cross-section along the line A-B of the geologic map. 



MAP. 



Geologic map of the Benguet mining region. 



TEXT FIGUEES. 



Fig. 1. Ideal section through the Benguet region east and west. 

 2. Aalborg kiln for lime burning. 



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