42 THE ROYAL SOCIETY OF CANADA 



beds could only have been formed during the final retreat and when 

 the sea margin had withdrawn from nearly all of the area now within 

 the boundaries of Canada. 



Although there seems to be proof of marine inclusions in the 

 Lance beds it must be assumed that the area, at that time a salt 

 marsh, must have been bordered by surfaces above the sea and pos- 

 sibly considerably elevated to give the slope necessary for the trans- 

 portation of the sandy material found. It is also clear that we now 

 consider the deposits on these land areas to be of Tertiary age while 

 the low-land formations may be Cretaceous. The Lance beds may 

 thus without violence to our theories represent a deposition in a low- 

 lying area subject to inundation from a sea still bearing a Cretaceous 

 fauna bordered by land areas bearing Tertiary flora; the various 

 fluctuations in level being reflected in alternating beds of apparent 

 Cretaceous and Tertiary ages. 



The correlation of this formation with deposits of the same time 

 will naturally be made with the earlier Tertiary continental deposits 

 of the interior called Paskapoo on account of the plant impressions 

 preserved or with the marine Cretaceous deposits in the Gulf region 

 whose presence at this time is indicated in the modified Fox Hills 

 fauna found in the Cannon Ball formation in the upper Lance. 



Nothwithstanding the presence of an early Tertiary flora in the 

 beds immediately above the Edmonton, i.e. the lower part of the 

 Paskapoo, it seems evident that their deposition was accomplished 

 at a time when the sea still bore Cretaceous invertebrates and dino- 

 saurs lived on the lowlands bordering the northward extension of 

 the gulf waters. The upper part of the Paskapoo formation and the 

 Porcupine Hills beds are no doubt Tertiary, but they cannot be sep- 

 arated from the underlying freshwater beds that may have been 

 formed at the close of the Cretaceous. 



The correlation suggested in the above paper and indicated on 

 the plates showing the extent of the sea at several periods is again 

 illustrated by its application to the areal geology as far as known in 

 Plate XL The northern part of the Cretaceous plateau is not well 

 explored and the areal geology is mostly conjectural, but the sug- 

 gestions of the possible mapping provide many problems for future 

 study. 



