PHYSKWF, IIISTOKV S? 



tiiuling its shore not fur to tlie east of this line. Further north, ultlioufj^h 

 not without insular interruptions, it spread over the entire widtli of the 

 Cordilleran helt, repeating the conditions found in the Triassic, l)utwith 

 the difference that it extended far to the south along the axis of the 

 Fiaramide geosyncline, in which rapid snhsidence had been renewed. Tn 

 this early Cretaceous sea and along its margins and lagoons the massive 

 fossiliferous rocks of the Queen Charlotte islands and Kootanie forma- 

 tions were accumulated and coal beds were produced. Volcanic activity 

 was renewed in some })laces, particular!}'' near the present seaward margin 

 of British Columbia. Sedimentation evidentl}' proceeded more rapidly 

 than subsidence in many localities and coal-producing forests, largely 

 composed of cycadaceous plants took possession of the newly formed 

 lands from time to time. 



The era of the later Cretaceous appears, however, eventualh^ to have 

 been introduced by a marked general subsidence, which, as already 

 noted, carried the Dakota sea entirely across the inland plain of the con- 

 tinent. The distribution and character of the ensuing Cretaceous for- 

 mations show that the whole southern part of what is now the mainland 

 of British Columbia soon after became and remained a land area, while 

 the sea was more graduall}^ excluded from the northern })art of the Cor- 

 dillera and continued to occupy the area of the Great plains and the 

 present position of the Laramide range. Along the margin of the con- 

 tinental plateau, however, a renewed subsidence was in the main pro- 

 gressing southward and resulted ultimate!}^ in carrying the later Cre- 

 taceous sediments into the region of Puget sound. 



The closing event of this cycle was the deposition of the Laramie 

 beds on the east and in some places to the north, with probably the 

 Puget group and its representatives on the coast, and this was followed 

 by the most important and widespread orogenic movement of which we 

 find evidence in the entire Rocky Mountain region. At this time the 

 great Laramide range, or Rocky Mountain range proper, was produced, 

 rising on the eastern side of the Archean axis along a zone that had pre- 

 viously been characterized from the dawn of the Paleozoic by almost 

 uninterrupted subsidence and sedimentation. That the pressure caus- 

 ing this upthrust of the Laramide range was from the westward is clearly 

 shown by the great overthrust faults in this range. The stabilit}' of the 

 old Archean axis, which it may be supposed had previously sustained 

 the tangential thrust from the Pacific basin, must at this time have been 

 at last overcome. As a part of the result of this, the chief belt of faulted 

 strata in the Laramide range, originally about 50 miles wide, became 

 reduced in width by one-half. How rapidly this great revolution may 

 have occurred we do not know, but it probably occupied no long tinie 



