Stromatolites of the Belt Series in Glacier National Park and Vicinity, Montana

127 S tratigraphy—Continued Introduction 127 Stromatolite zones—Continued Previous investigations 127 Ravalli group—Continued Page Present investigation 127 Grinnell argillite 136 Area of investigation 128 Collenia undosa zone 1 136 Acknowledgments 129 Piegan group 137 Classification of stromatolites 129 Siyeh limestone 137 General 129 Collenia symmetrica zone 1 137 Previous classifications 130 Conophyton zone 1 138 Pres * ent classification 131 Collenia multiflabella zone 138 Generic distinction 131 Missoula group 139 Specific characteristics 131 Collenia undosa zone 2 139 Gross form of colony 131 Collenia symmetrica zone 2 139 Nature of the laminae 132 Conophyton zone 2 140 Size of colony 132 Types 132 Ecology 141 Key to the identification of stromatolites in the Belt Modern environments 141 series 132 Origin of stromatolites 146 Descriptions of genera and species 132 Paleoecology 147 Genus Cryptozoon Hall 132 Collenia frequens zone 147 Genus Collenia Walcott 133 147 Newlandia lamellosa Genus Newlandia Walcott 134 Collenia undosa zones 147 Genus Conophyton Maslov 135 Collenia symmetrica zones 148 Stratigraphy 135 Conophyton zones 148 General 135 Collenia multiflabella zone 148 Stromatolite zones 136 Conclusions 149 Ravalli group 136 Altyn limestone 136 Selected bibliography 149 Collenia frequens zone 136 Index 153