10 CONTENTS. 



CHAPTER V. DESCRIPTIVE GEOLOGY OF MINES AND PROSPECTS Continued. Page. 

 The known earlier andesite veins Continued. 

 Montana Tonapah vein system Continued. 



Midway workings 179 



Later andesite in shaft 179 



Typical early andesite in shaft 179 



Tonopah rhyolite-dacite in shaft 179 



Formation exposed by drifting 179 



Veins in the Midway 180 



Tonopah Extension mine 181 



Contact of earlier and later andesites. .'. 181 



Veins in the earlier andesite 182 



Veins in the Tonopah rhyolite-dacite 183 



Other exploratory workings, wholly or partly in early andesite 184 



West End workings 184 



Outcrop of West End fault 184 



Rhyolite intrusion along fault 184 



Character of andesite above 220-foot level 185 



Character of andesite on 220-foot level 186 



Correlation of andesites in West End and Fraction workings 186 



Extension of correlation to the Wandering Boy and to Gold Hill 186 



The West End andesite probably earlier andesite 187 



Contact between earlier and later andesites 187 



Place and character of contact 187 



Nature of similar contacts elsewhere 187 



Tonopah rhyolite-dacite 188 



Earlier andesite at bottom of shaft 188 



MacNamara workings 189 



Later andesite at surface 189 



Character of andesite on 200-foot level 189 



Correlation of MacNamara and West End andesites 189 



Contact of earlier and later andesites 190 



Tonopah rhyolite-dacite and included veins 190 



Explorations on veins at the contacts of the Oddie rhyolite 191 



Wingfleld tunnel 191 



Boston Tonopah shaft 192 



M iriam shaft 193 



Desert Queen shaft 193 



Shafts at the unmineralized contact of the Oddie rhyolite 193 



Hi-lmont shaft 193 



Rescue shaft 194 



Explorations on veins at the contact of the Tonopah rhyolite-dacite 194 



Mizpali Extension shaft 194 



I>ater andesite at top of shaft 194 



Rhyolite and rhyolite-dacite in shaft 195 



Veins at contact of Tonopah rhyolite-dacite 195 



