542 



THE CRETACEOUS PERIOD 



as much as seven miles, 1 and the throw 15,000 feet. Near the na- 

 tional boundary, the displacement along what appears to be the same 

 fault crowded the Proterozoic up over the Cretaceous 2 by a move- 

 ment of equal magnitude (Fig. 457). The exact date of these faults 

 has not been determined, but was, perhaps, mid-Tertiary. 



Fig. 458. Chief Mountain. (Willis, U. S. Geol. Surv.) 



Igneous eruptions. The close of the Cretaceous was marked by 

 the inauguration of a period of exceptional igneous activity, con- 

 tinuing far into the Tertiary. During this period, great bodies of 

 igneous rock, both extrusive and intrusive, were forced up. Erup- 

 tions occurred in other lands at about the same time. 



Upper Cretaceous of Other Continents 3 



Europe. The distribution of the Upper Cretaceous strata of 

 Europe shows that extensive transgressions of the sea occurred at 

 the beginning of the period, for in some parts of the continent 

 marine Cretaceous formations overlap all older Mesozoic systems. 

 During the closing stages of the Upper Cretaceous, fresh- water beds 



1 McConnell, Geol. Surv. of Canada, Vol. II, Rept. D, p. 33, 1886. 



2 Willis, Bull. Geol. Soc. of Am., Vol. XIII, pp. 307, 331-335. 



3 The term Comanchean has not been applied outside of North America, and 

 the Cretaceous system will therefore be referred to as Upper Cretaceous. 



