1889. J NEW YORK ACADEMY OF SCIEXCES. 29 



between the testimony of the plant and animal remains, and 

 would have refrained from making the statement quoted above, 

 which has done much to produce and prolong confusion in the 

 minds of geologists, where none exists in the geological record. 



Dr. Hayden primarily considered all of his Laramie (Laramie 

 and Fort Union) as Tertiary, but his latest conclusion was that 

 the whole mass was of a transitional character, — beds of passage 

 between the Cretaceous and Tertiary. It is easy to see that this 

 result was inevitable, after he had united an Upper Cretaceous 

 with a Tertiary formation under one name. The typical locali- 

 ties and representatives of the Laramie group are, according to 

 Dr. Hayden, as follows:—!, Placer Mt., N. M.; 2, Caflon City, 

 Oolo. ; 3, Fort Union or Lignite group, Dakota, Montana, and 

 Wyoming; 4, Bitter Creek series, Wyoming; 5, Bear Eiver group, 

 western Wyoming; 6, the Judith River beds, Montana, which he 

 provisionally placed below the Fort Union series, but considered 

 their age doubtful. 



Of the strata exposed in these localities, Nos. 1, 2, 4, 5, and 6 

 are now known to be Lower Laramie and Cretaceous; while the 

 Fort Union group has nothing in common with these, and, as 

 will be shown further on, has been proved to be Eocene. 



Of the Judith River and Fort Union beds, Mr. Meek, as early 

 as 1872, says (Hayden's Annual Report, p. 460):— "That the 

 Judith River beds may be Cretaceous, I am, in the light of all 

 now known in this region of the continent, rather inclined to 

 believe; but it would take strong evidence to convince me, that 

 the higher fresh-water Laramie series [Fort Union] of the Up- 

 per Missouri is more ancient than the Lower Eocene. That 

 they are not is certainly strongly indicated by the modern affini- 

 ties of their molluscan remains, and also by the state of preser- 

 vation of the latter." 



Mr. Leo Lesquereux, in the annual reports of Dr. Hayden, by 

 whom he was employed for many years, and especially in his 

 " Tertiary Flora," * has written much in regard to the Fort 

 Union and Laramie groups. In the introduction to tiie latter 

 work, ho discusses the Lignite formation of North America at 

 length, and treats, first, of the " areal distribution"; second, 

 "stratigraphy and capacity of combustible mineral," and third, 

 *'its age indicated by its geological distribution and its fau- 

 na." In this comprehensive paper he summarizes the obser- 

 vations made by himself and others; and Dr. Hayden claims, 

 in his letter of transmission, that he settles the question of the 

 age of the Lignitic group, which he regards as one and indivis- 

 ible, and proves it to be all Tertiary. 



' Report of the Geological Survej' of the Territories, Vol. VII. 



