CONTENTS. 



Page. 



LETTER OF TRANSMITTAL 19 



OUTLINE OP PAPER 21 



INTRODUCTION 25 



Location 25 



Topography 25 



Discovery 25 



Development 26 



Treatment of ores 28 



Water supply 28 



Fuel and power 28 



CHAPTER I. GENERAL GEOLOGY 30 



Description of the rock formations 30 



Pre-Tertiary limestone and granite 30 



Tertiary lavas 31 



Andesi tes 31 



Earlier andesite (hornblende-biotite-andesite) 31 



Appearance 31 



Original composition 31 



Present altered condition 31 



Location 32 



Later andesite (biotite-augite-andesite) 33 



Appearance 33 



Composition and alteration 33 



Location 34 



Relation to earlier andesite 35 



Distinction from earlier andesite 35 



Rhyolites and dacites 36 



Interrelation of rhyolites and dacites 36 



Simultaneous eruptions 36 



Heller dacite 37 



Location 37 



Age of Heller dacite 38 



Nature of Heller dacite 38 



Microscopic characters 39 



Fraction dacite breccia 39 



Location 39 



Thickness 39 



Conditions of eruption 39 



3 



