THE ROCKY MOUNTAIN EEGION OF CANADA. 19 



the marine beds of the Pierre and Fox Hill groups, more than 1,700 feet in thickness, intro- 

 duces the Laramie or Daniau llora, which continues to the top of the Cretaceous, and 

 probably into the Eocene, and includes several species still surviving on the American 

 continent, or represented by forms so close that they may be varietal merely. 



Lastly : the subdivision of the Laramie group, in the last report of Dr. Gr. M. Dawson, 

 into the three members known respectively as the Lower or St. Mary River series, the 

 Middle or Willow Creek series, and the Upper or Porciipiue Hill series, in connection 

 with the fact that the fossil plants occur chiefly in the lower and upper members, enables 

 us now to divide the Laramie flora proper into two sub-floras, — an older, closely allied to 

 that of the Belly River series below ; and a newer, identical with that of Souris River, 

 described as Laramie in Dr. Gr. M. Dawson's Report on the 49th Parallel, 18*76, and in the 

 Report of the Geological Survey of Canada for 18*79, and which appears to agree with that 

 known in the United States as the Fort Union group, and in part at least with the so- 

 called Miocene of Heer from Greenland. 



From the animal fossils and the character of the flora, it would seem probable that 

 the rich flora of the Cretaceous coal fields of Vancouver Island is nearly synchronous with 

 that of the coal-bearing Belly River series of the western plains. 



It will thus be seen that the explorations already made in Canadian territory have 

 revealed a very complete series of Cretaceous plants, admitting, no doubt, of large addi- 

 tions to the number of species by future discoveries, and also of the establishment of con- 

 necting links between the different members, but giving a satisfactory basis for the know- 

 ledge of the succession of plants and for the determination of the ages of formations by 

 their vegetable fossils. 



In connection with the subjoined table it should be understood that Tertiary floras, 

 probably Miocene in age, are known in the interior of British Columbia, though they 

 have not yet been recognized in the territories east of the Rocky Mountains. 



Before leaving this part of the subject, I would deprecate the remark which I see 

 occasionally made, that fossil plants are of little value in determining geological horizons 

 in the Cretaceous and Tertiary. I admit that in these periods some allowance must be 

 made for local difierences of station, and also that there is a generic sameness in the flora 

 of the Northern Hemisphere, from the Cenomanian to the modern, yet these local differences 

 and general similarity are not of a nature to invalidate inferences as to age. No doubt so 

 long as palfeobotanists seemed obliged, in deference to authority, and to the results of 

 investigations limited to a few European localities, to group together, without distinction, 

 all the floras of the later Cretaceous and earlier Tertiary, irrespective of stratigraphical 

 considerations, the subject lost its geological importance. Bixt when a good series has 

 been obtained in any one region of some extent, the case becomes difl'erent. Though there is 

 still much imperfection in our knowledge of the Cretaceous and Tertiary floras of Canada, I 

 think the work already done is sufficient to enable any competent observer to distinguish by 

 their fossil plants the Lower, Middle and Upper Cretaceous, and the latter from the Tertiary ; 

 and, with the aid of the work already done by Lesquereux and Newberry in the United 

 States, to refer approximately to its true geological position any group of plants from beds 

 of unknown age in the west. 



The successiA'e series may be tabulated as follows, with references for details to the 

 fuller table in my memoir of 1883 ; — 



