TRIASSir 7.> 



out the entire series. The tuffs are occasionally calcareous, and there 

 are some thin and prohably irregular beds of limestone, with infreijuent 

 layers of argillite. Tlie most complete section so far obtained is one on 

 the Thompson river, showing a total thickness of lo.oDO feet; another 

 near Nicola lake gives a probable minimum of 7,500 feet, and in both 

 places more than nine-tenths of the whole is of volcanic origin. 



The Nicola formation, with the characteristics above noted, is well de- 

 veloped in the central parts of the Interior plateau of British Columbia, 

 and it probably extends fiir to the north in the same belt of country be- 

 tween the Coast and Gold ranges, but in the general absence of paleon- 

 tological evidence, can not there as yet be separated, even locally, from 

 the Paleozoic.'^ 



To the west of the Coast ranges, and now entirely separated from the 

 Nicola formation by the granitic mass of these ranges of later age, Triassic 

 rocks are again found largely developed in the Queen Charlotte islands 

 and on Vancouver island. They were described and identified in the 

 Queen Charlotte islands in 1878, and in 1885, when again found cover- 

 ing large areas in the northern part of Vancouver island, were defined 

 as the Vancouver series.f 



These rocks closely resemble those of the Nicola formation, with which 

 they may probabl}^ at the time of their deposition have been continuous. 

 The series is built up for the most part of volcanic materials, now in 

 the state of altered diabases and felsites, but amygdaloidal, agglomeratic, 

 or tuffaceous in character. Ordinary sedimentary materials, such as 

 argillites, limestones, and felsites, are, however, more abundant than in 

 the Nicola formation. These probably recur at several different hori- 

 zons, but in the northern part of Vancouver island they are known to 

 form an important zone, with a thickness of about 2,500 feet.;|: Marine 

 fossils are abundant in some of these beds. 



This group is of great thickness, but no trustworthy figures can yet 

 be given for it. It is associated often with the very similar rocks of the 

 Carboniferous period, already referred to as existing in the same oro- 

 graphic belt, and it yet remains to draw a distinct line between the two 

 series. Following the coastal region northward, rocks pretty clearly 

 referable to this formation have been noted in several places among the 

 Alaskan islands as far up as Lynn canal. 



To the north of the 56th degree of latitude, it would appear that the 



* Annual Report, Geol. Surv.' Can., vol. iii (N. S. ), p. 33 B. 



t Report of Progress, Geol. Surv. Can., 1878- 79, p. 49 B. Annual Report, Geol. Surv. Can., vol. 

 ii (N. S.), p. 7 B et seq. The rocks named the Sooke series, in 1876, may probably also be included 

 in the Vancouver series. Report of Progress, Geol. Surv. Can., 1876-'77, pp. 98-102. 



I The same zone is probably represented in the southern part of the Queen Charlotte islands. 



XII— Bum,. Geoi.. Soc. Am., Vol. 12, 1900 



