THE GEOLOGY OF SANTA CATALINA ISLAND. 



BY WILLIAM SIDNEY TANGIER SMITH. 



Candidate Ph. Z>., University of California. 



CONTENTS. 



PAGE. 



PLATES I III. 



I. INTRODUCTION 2 



1. LITERATURE 2 



2. GENERAL DESCRIPTION 3 



II. TOPOGRAPHY 5 



1. MAJOR FEATURES 4 



Main Ridge 4 



Types of Topography 5 



Slope of Summits 6 



Two Types of Drainage 7 



2. MINOR FEATURES 8 



Echo Lake 8 



Sea Cliffs 9 



Bays 10 



Beaches 10 



Terraces n 



III. GEOLOGY. 13 



A. ERUPTIVE ROCKS 14 



1. DIORITE 14 



Macroscopic Characters 14 



Microscopic Characters 15 



2. PORPHYRITE 19 



Occurrence 19 



Character 19 



Macroscopic Characters 20 



Microscopic Characters 20 



Analysis 25 



Inliers of Basement Rocks 25 



Porphyrite Dykes 26 



3. RHYOLITE 28 



Occtirrence 28 



Macroscopic Characters 28 



Microscopic Characters , 29 



4. ANDESITE 30 



Occurrence 30 



Macroscopic Characters 31 



Microscopic Characters 32 



Glassy Fades 35 



Basaltic Fades 37 



Analysis 41 



[ i | January 12, 1897. 



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