28 TRANSACTIONS OF THE | NOV. 4^ 



tion contained in the Eeport of the Exploration of the Fortieth 

 Parallel, Vol. I., " Systematic Geology," p. 348 et seq. 



Since the publication of Mr. King's report in 1878, much has 

 been written upon the Laramie group by Dr. Hayden, Mr. Leo 

 Lesquereux, Dr. C. A. White, Prof. J. J. Stevenson, Prof. L. F. 

 Ward, and myself. The Tertiary character of the Fort Union 

 flora was recognized by all; whereas the vertebrates and moUusks 

 of the true Laramie of King (the Lower Laramie of Hayden) 

 are so distinctly Cretaceous m their affinities that the Laramie 

 came to be considered by most, as it was asserted by some, to be 

 a formation intermediate in age between Cretaceous and Ter- 

 tiary. Hayden in his later reports and maps designated it as 

 Post-Cretaceous, 



Much undeserved discredit has also fallen upon the remains of 

 plants, as criteria of the age of strata, and much mischief and 

 confusion have followed the error of Dr. Hayden in uniting with 

 the Laramie the totally distinct and independent Fort Union 

 formation. 



Prof. E. D. Cope, in the concluding paragraphs of his discus- 

 sion of the age of the Laramie and Fort Union groups,' suppos- 

 ing them to be parts of one formation, says: "I have alluded 

 but cursorily to the opinions of Mr. Lesquereux and Dr. New- 

 berry as based upon the study of the extinct flora. The former 

 has, as is well known, pronounced this whole series of forma- 

 tions to be of Tertiary age and some of the beds as high as 

 Miocene. The material on which this determination is based is 

 abundant and must be accepted as demonstrated beyond all 

 doubt. I regard the evidence derived from the mollusks in the 

 lower bed?, and the vertebrates in the higher, as equally conclu- 

 sive that the beds are of Cretaceous age. There is then no alter- 

 native but to accept the result that a Tertiary flora toas contem- 

 poraneous ivith a Cretaceous faiina, establishing an uninterrupted 

 succession of life across what is generally regarded as one of the 

 greatest breaks in geologic time. The circumstance of the dis- 

 covery of a Mesozoic Dinosaur, Agathaumas sylvestre, with the 

 cavities between its bones stuffed full of leaves of Eocene plants, 

 would prove this proposition to be true had no other fossils of 

 either kind ever been discovered elsewhere." 



The locality where the bones and leaves referred to above were 

 found is Black Butte Station, and the horizon the Laramie for- 

 mation near its base. If Prof. Cope had not accepted Mr. 

 Lesquereux's conclusion in regard to the age of the deposit, and 

 had recognized the fact that there are no Tertiary plants in the 

 true Laramie, he would have seen that there is no discrepancy 



' '• Geological Survey of the Territories," Vol. II., p. 40. 



