96 CONTENTS OF PART II. 
Chapter III. Clastic rocks — Continued. p age . 
Volcanic sandstones arid conglomerates 126 
Field description 127 
Volcanic conglomerate on Welts Brook 127 
A r olcanic conglomerates of Ashland Township 127 
Volcanic conglomerates of New Sweden Township 127 
Volcanic conglomerates of Perham Township 128 
Volcanic conglomerates of Madawaska Lake 128 
Petrography 128 
Volcanic conglomerate on Welts Brook 128 
Volcanic conglomerates of Ashland Township 129 
Volcanic conglomerates of New Sweden Township 129 
Microscopic description 130 
Volcanic conglomerates of Perham Township 130 
Volcanic conglomerates of Madawaska Lake 131 
Sandstones and conglomerates 131 
Sheridan sandstone 132 
Fine-grained variety 132 
Coarse conglomerate variety 133 
Chapman sandstone 133 
Mars Hill conglomerate 134 
Rock structure 135 
Mapleton sandstone 136 
Winslows Hill section 136 
Petrography 137 
Field relations 137 
Sandstones of other localities 137 
Calciferous quartzitic sandstone 138 
Analysis 138 
Limestones 139 
Arenaceous limestones 140 
Aroostook limestone 141 
Previous study 141 
Structure 142 
Petrography 142 
Heavy beds of limestone 142 
Fossiliferous limestone 143 
Slates and schists 143 
Manganiferous iron slates 145 
Chapter IV. Petrography of the igneous rocks 146 
Granites 146 
Mapleton granite 146 
Dark aggregates in the Mapleton granite 148 
Drews Lake granite 148 
Dikes of the granite areas 149 
Aplite 149 
Syenite 149 
Granite-porphyry 150 
Kersantite 151 
Metamorphism caused by the granites and associated dikes 151 
Mapleton area 151 
Drews Lake area 152 
Rhyolites 152 
