FAUNAL MIGRATIONS AND DIASTROPHISM 399 



As I read the evidence from the vertebrates it is to this effect : 



( 1 ) From the Belly Eiver to the Lance there is a considerable lapse in 

 time, but they represent the same faunal facies and they indicate that 

 there was no great migration movement intervening, and hence no great 

 upheaval, eitlier continental or universal. There was undoubtedly a con- 

 siderable local uplift along the Rocky Mountain ridges and extensive 

 recession of the sea from the plains to eastward of them. 



(2) Bet\\'een the Lance and the Paleocene there is a somewhat smaller 

 lapse in time, but a very marked change in fauna ; but they do not repre- 

 sent the same facies, and while a great migration movement is probably 

 indicated by the extinction of the Dinosaur phyla and incoming of cer- 

 tain groups of placental mammals (Creodonta, Condylarthra, etcetera) 

 its extent remains a little uncertain. 



(3) Between the Paleocene and Eocene a great migration movement 

 intervenes, the progressive orders of placental mammals, of turtles, and 

 perhaps other groups appearing simultaneously in Europe and North 

 America. The lapse of time between the uppermost Paleocene and lowest 

 Eocene is slight. 



If, therefore, we are to use diastrophic criteria as the basis of our geo- 

 logic classification, the dividing line between Cretaceous and Tertiary 

 should be drawn either between the Lance and the Paleocene or between 

 the Paleocene and Eocene. It should not be drawn between Belly River 

 and Lance. 



It is perhaps apropos to recall that the late Professor Cope was for a 

 long time of the opinion that the Paleocene should not be included in the 

 Tertiary, but distinguished along with the Lance and associated faunae 

 a-s post-Cretaceous. Doct(?r Hay has also expressed the opinion that it 

 might be better to include the Puerco and perhaps also the Torre j on in 

 the Cretaceous. 



Conclusions 



The question to my mind shapes itself thus : Does the evidence con- 

 clusively support the present classification ; and, if not, is it sufficiently 

 conclusive to warrant our changing it? I have indicated what I regard 

 as the weight and trend of the vertebrate evidence. Without entering 

 into any detailed criticism of the stratigraphic and paleobotanic evidence* 

 a task for which others are far more competent, I may say that to me it 

 appears to be inconclusive because it does not allow for the characteristics 

 of epicontinental formations nor for the varying facies of faunas and 



