CAMBRIAN GEOLOGY AND PALEONTOLOGY 



II 



No. 12.— CAMBRIAN FORMATIONS OF THE ROBSON 



PEAK DISTRICT, BRITISH COLUMBIA AND 



ALBERTA, CANADA 



By CHARLES D. WALCOTT 



(With Plates 55-59) 



CONTENTS PAGE 



Introduction 328 



Geological section 329 



Location of the section 330 



Lower Cambrian 330 



Middle Cambrian 330 



L'pper Cambrian 330 



Ordovician 331 



Nomenclature 331 



Changes in names 331 



New names 332 



New formation names 334 



Stratigraphic section from Robson Peak north-northwest to Moose Pass. . 336 



Ordovician system 336 



Cambrian system 2>2>7 



Upper Cambrian 2>2i7 



Middle Cambrian 2i2>7 



Lower Cambrian 338 



LTnconformity by erosion 340 



Pre-Cambrian 340 



Summary of Robson district, stratigraphic section 341 



Summary of Mount Bosworth section, stratigraphic section 342 



Comparison of Robson section with Bosworth section 342 



Comparative stratigraphic sections 343 



Robson district 343 



Mount Bosworth section 343 



Smithsonian Miscellaneous Collections, Vol. 57, No. 12 



2>27 



