UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 4, No. 1, pp. 1-32, Pis. 1-4 ANDREW C. LAWSON, Editor 



THE GEOLOGY OF THE UPPER REGION 



OF THE 



MAIN WALKER RIVER, NEVADA. 



BY 



D wight T. Smith. 



CONTENTS. 



Page. 



Introduction 2 



Physical Features of the Region 3 



Distribution of Formations 4 



The First Ridge 2 



Sing-ats'-e Eidge 4 



The Third Ridge 7 



Whirlwind Mountain 8 



The Mid-valley Buttes 9 



Unconformities 9 



The Bedrock Complex and the Tertiary 9 



The Tertiary and the Quaternary 11 



Relative Age and Unconformity of Igneous Rocks 12 



Structure 12 



The Bedrock Complex 12 



The Tertiary 13 



Relief of pre-Tertiary and Tertiary Surfaces as compared with the 



Present Relief 15 



Explorations beyond the Region mapped l(i 



Description of the Igneous Rocks 17 



The Granitic Rocks 17 



The Porphyrite 23 



The Hornblende Andesite 23 



The Later Andesite 25 



The Rhyolite 25 



The Basalt 26 



The Schists 28 



Sequence of Igneous Rocks 28 



Ore Deposits 28 



Geology of Deposits 28 



The Deposits in Particular 29 



An Occurrence of Native Copper s 32 



