129 



paleozoic age, and in the ensuing 2'>ei"io(l, the Triassic, we take up the- 

 third great division of geologic time, the Mesozuic. 



The development of the Triassic rocks in Eastern Canada is very 

 limiteil, certain small areas in Nova Scotia, New Brunswick and 

 Prince Edward Island, in all of only a few square miles in extent, com- 

 prising all that is present known of the formation between the Atlantic 

 and the piairie section. Small areas have been recognized in the Rocky 

 Mountain district, and on the Pacific coast, in Queen Charlotte Islands 

 and in Vancouver, beds supposed to be of this age have been found under - 

 hing the Cretaceous and coataining characteristic fossils. 



The Cretaceous or third division of the Mesozoic is, however, largely 

 developed in that ]>ortion of the Dominion lying to the east of the 

 Rocky Mountains as well as in British Columbia. It both places it is 

 remarkable for the j)resence of immense beds of coal which at times 

 almost rival in tliickness the gi'eatest beds of Nova Scotia, The great 

 abundance and variety ot fossils in these localities clearly indicate the 

 horizon of these beds, while the presence of such great seams of coal on 

 either side of the Rockies renders this formation of the e:reatest econ- 

 omic importance. The newer Tertiary formations are sparingly developed 

 in Canada, a few localities in the North- West Territories closely asso_ 

 ciated with the Cretaceous and for some years almost inseparable, having 

 of late been judged to belong to this period of time. But the great 

 thickness of formations which are found in England and France, and 

 which there complete the geological record, are, in so fi\r as yet known, 

 almost absent from this portion of the American continent. 



Throughout the long interval of the many millions of years which 

 elapsed between the beginning of the fossilifei'ous rocks aud the close 

 of the Tertiary many eras of subsidence and elevation of the earth's 

 crust must have taken place, and are evidenced very plainly by the 

 varying chai-acter of the sediments. Thus conglomerates and coarse 

 grits are supposed to represent shallow water and beach deposits, while 

 fine slates represent deposition of sediment under deeper and quieter 

 conditions. From the obsei-vation of these peculiarities some authors 

 have developed the theory of geological cycles, by which is meant a 

 regular periodical recurrence of the physical conditions of the earth's 



