CONTENTS OF PART IT. ( .)7 
hapter IV. Petrography of the igneous rocks — Continued Page. 
Rhyolites — Continued . 
Rock of the main mountain mass 153 
Macroscopic description 1 53 
Microscopic description 1 53 
Analysis 1 55 
White type _ 1 56 
Perlitic type . . . . 157 
Macroscopic description 157 
Microscopic description . _ _ _ 157 
Rhyolite breccia 158 
Macroscopic description 158 
Microscopic description 159 
Vesicular lava 159 
Macroscopic description 1 00 
Microscopic description 100 
Trachytes 101 
Hedgehog trachyte 1 01 
Trachyte of Chapman Township 102 
Macroscopic description 1 02 
Microscopic description 102 
Analysis 103 
Doubtful trachytes 10-1 
Quoggy Joe quartz-trachyte 104 
Macroscopic description 104 
Microscopic description 165 
Analysis .• 106 
Discussion of analysis 166 
Classification 107 
Quartz-trachyte of Township 9, Range 3 168 
Andesites 168 
Augite-andesite 169 
Macroscopic description 169 
Microscopic description 169 
Analysis 171 
Hornblende-andesite 172 
Microscopic description 172 
Southern Mapleton andesites 173 
Castle Hill andesites 174 
Macroscopic description 174 
Microscopic description 174 
Andesite ash beds 175 
Diabase 1 75 
Aroostook Falls diabase 175 
Analysis , 1 76 
Discussion of analysis - . , 177 
Mars Hill diabase 177 
Normal type 177 
Microscopic description 177 
Glassy type 1 78 
Analysis - - - 178 
Discussion of analysis 179 
Teschenites 179 
Field appearance , 1 79 
Bull. 165 7 
