The discussion of the various opinions which have been put forth from time to time during the last half century as to the age and geological position of the different members of the peculiar series of rocks known among geologists generally by the term “Quebec group,” would be an undertaking too great for the limits of an ordinary paper. It is, moreover, to a great extent rendered unnecessary in this place from the fact that the history has already been given with considerable completeness in several publications, among which may be chiefly enumerated papers by Dr. T. Sterry Hunt and Professor Jules Marcou, as well as by the writer, who, in the volume of the Geological Survey of Canada, just issued (1887–888), has gone into the subject with some detail. This course was deemed advisable, and in fact almost necessary, owing to the variety of statements, many of . . .