74 a. :\r. dawson — rocky mountain region in can ad a 



Triassic sea extended eastward, without important interruption, across 

 the entire Cordilleran region, as marine fossils like those of the Van- 

 couver group have been found not only on the Stikine (in the trend of 

 the Nicola formation), but also on the Liard, Peace, and Pine rivers in 

 the Laramide range.^ In the last named range, however, there is no 

 evidence of contemporaneous volcanic action, which, it is probable, did 

 not extend so far to the eastward. 



Following the Laramide range southward from the occurrences last 

 alluded to, there is a considerable interval in which no Triassic rocks 

 have been recognized, after whicli, in the vicinity of the 49th parallel, 

 a series of red sandstones and shales, with buff magnesian grits, three or 

 four hundred feet thick, is found. This caps a number of the higher 

 mountain ridges and was assigned b}^ me in 1875 to the Triassic. It is 

 believed to represent the northern extremity of the deposits of the Tri- 

 assic Mediterranean that occu})ied so large a part of the Western states 

 and which must have been separated from the open sea b}^ land barriers 

 of some width. t 



Cretaceous 



Apart from the beds capping the Nicola formation, to which allusion 

 has been made, no strata distinctly referable to the Jurassic have been 

 found in the Rocky Mountain region of Canada. Wherever their rela- 

 tions have been determined, the Cretaceous rocks lie unconformabl}^ on 

 the Nicola and Vancouver formations, and it seems probable that this 

 unconformity represents the greater part of the Jurassic period. It is 

 proper, however, to state that the lower measures here included in the 

 Cretaceous are still by some authorities called Jurassic; but it is be- 

 lieved that the paleontological evidence, when compared with the best 

 recognized general standards (and not merely with local isolated devel- 

 opments to which a Jurassic age happens to have been assigned), is 

 overwhelmingly in favor of the Cretaceous reference.^ 



There is in the region here treated of an important Earlier Cretaceous 

 series of rocks, mostly of marine origin, the distribution of which shows 



* Annual Report, Geo). Surv. Can., vol. iii (N. S.), p. niB. Ibid., vol. iv, p. lit 1). Rt-port of 

 Progress, Geol. Surv. Can., 1875-'76, p. 97. Bull. Geol. Soc. Am., vol. v, p. 122. 



t Geology and Resources of 49th Parallel, 1875, p. 71. Trans. Royal Soc. Can., vol. i, sec. iv, p. 14.3 

 et seq. 



JCf. Wliiteaves : Mesozoic Fossils, vol. i, part iv, 1900. 



In a late article in the Journal of Geology (Chicago), vol. viii, pp. 240-258, Mr W. N. Logan 

 groups the Jurassic beds found at the summit of the Nicola group {not at Nicola lake) with parts 

 of the Queen Charlotte and Kootanie formations, here described as Earlier (^retaceous, and which 

 we have found no reason to separate from the rest of tliat series, calling the whole Jurassic By 

 eo doing lie gives a large part of the area of the Earlier Cretaceous sea to the Jurassic, in a man- 

 ner which I believe to be incorrect (cf. Am. Jour. Sci., vol. xx.^viii, p. 121). 



