It is the privilege of the President of this Society, in his address, to bring to the notice of his fellow-members some subject possessed of more or less general interest, and preferably, I think, some subject that he has made particularly his own. On such an occasion a wider outlook upon various geological fields becomes admissible than in the case of papers presented to the Society, which, as a rule, should be devoted to original and unpublished observations. It has thus appeared to me that it may be of interest and utility at this time, to collect and review the main facts so far ascertained respecting the composition of the geological column of what may be called the Rocky Mountain region of Canada, including the province of British Columbia and the Yukon district—this region being identical with that part of the western Cordillera comprised in the Dominion of Canada. . . .