277 



Where Do the Lance Creek ("Ceratops") Beds Belong, 



in the Cretaceous or in the Tertiary? 



By Oliver P. Hay. 



CONTENTS. 



PAG 



1. Historical Resume 277 



2. Necessity for accurate correlation of the primary divisions of the geological column 



in the different continents 279 



3. The primary divisions are not usually indicated by great unconformities 280 



4. The principal divisions of geological history are based on fossil organisms 283 



5. The value of plants as indices of geological dates 286 



6. Completeness of record of animal life as compared with that of plant life 288 



7. The beginning of the Eocene in Europe and America 289 



8. Relationships of fauna of Lance Creek epoch to those of Puerco and Torrejon .... 290 



Fishes, tailed amphibians, C'hampsosaurus 296 



Crocodiles, turtles 297 



Dinosaurs 299 



9. Relationships of Lance Creek fauna to that of the Judith River epoch 295 



10. Conclusions 303 



Historical Resume. 



Ever since the beginning of our knowledge of the geology of the West- 

 ern plains and the Rocky Mountains there have existed contentions re- 

 garding the various deposits to which the names Laramie and Fort Union 

 have been applied. These contentions have concerned the grouping of the 

 various beds, the geological horizons to which the deposits of different 

 basins and of different levels should be referred, and the members to 

 which the names Laramie and Fort Union respectively should be re- 

 stricted. Up to about the year 1896 certain deposits in the Judith River 

 basin and others in Montana, Wyoming, Colorado and New Mexico were 

 all regarded as the products of a single geological epoch and were all 

 called Laramie. Although as early as 1860, or even earlier, some geolo- 

 gists, especially Dr. F. V. Hayden and Professor Leo Lesquereux, basing 

 their opinion on the fossil plants, held that all or the greater part of the 

 deposits in question belonged to the Tertiary, the prevailing opinion up to 

 1896 was that the Laramie, taking the term in its widest sense, was the 

 uppermost portion of the Cretaceous. It may be said, however, that Pro- 

 fessor Cope in his great work "The Vertebrata of the Tertiary Forma- 

 tions of the West" referred the Laramie, as well as the overlying Puerco 



