HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



13 



this formation, at least on the basis of the 

 original definition by King. Some phases of 

 this history will be set forth in the following 

 pages. 



One of the first to take up the study of the 

 Laramie from both the geologic and the pale- 

 ontologic sides was Charles A. White. In the 

 first paper in which he employed the term 

 Laramie i7 the use was relatively unimportant 

 and the term was not defined. He gave two 

 generalized sections — one of the Green River 

 region, in which he placed the Laramie in its 

 proper position between the Fox Hills and the 

 Wasatch beds, and within the larger grouping 

 of post-Cretaceous, which also includes the 

 lower part of the Wasatch; and the other of the 

 upper Missouri River region, in which the 

 Laramie was not included but its place was 

 taken by the Judith River "group," while the 

 post-Cretaceous was made to include this and 

 a portion of the overlying Fort Union. 



White's reasons for regarding the Laramie as 

 post-Cretaceous were set forth in the fifth of 

 his "Paleontological papers" 4S published in the 

 same volume as the paper just cited. He said 

 that all who had examined the fossils from the 

 Dakota, Colorado, and Fox Hills deposits as 

 they are developed in southern Wyoming and 

 adjacent parts of Utah and Colorado, whether 

 vertebrate or invertebrate, would not question 

 their Cretaceous age. The fossils of the Green 

 River and Bridger strata were said to disclose 

 equally conclusive evidence of their Tertiary 

 age. He went on to say that the two groups 

 of beds between the Fox Hills below and the 

 Green River above are the Laramie and 

 Wasatch, and that somewhere within these 

 vertical limits must come the line between 

 Cretaceous and Tertiary. He then continued: 



With a few doubtful exceptions, none of the strata of 

 the Laramie group were deposited in open- sea waters; 

 and with equally few exceptions, none have yet furnished 

 invertebrate fossils that indicate the Cretaceous rather 

 than the Tertiary age of the group. * * * Again, the 

 brackish and fresh water types of Mollusca that are afforded 

 by the Laramie and the lower portions of the Wasatch 

 group are in most cases remarkably similar, and some of 

 the species of each group respectively approach each 

 other so nearly in their characteristics that it is often 



« Catalogue- of the invertebrate fossils hitherto published from the 

 fresh and brackish water deposits of the western portion of North 

 America: U. S. Geol. and Geog. Survey Terr. Bull., vol. 3, pp. 607-614, 

 May 15, 1877. 



48 idem, pp. 625-629. 



85344—22 2 



difficult to say in what respect they materially differ. 

 Moreover, they give the same uncertain indication as to 

 their geological age that all fossils of fresh and brackish 

 water origin are known to do. 



It is in view of the facts here stated, and also because 

 I believe that a proper interpretation of them shows the 

 strata of the Laramie group and the base of the Wasatch 

 to be of later date than any others that have hitherto 

 been referred to the Cretaceous, and also earlier than the 

 Eocene epoch, that I have decided to designate those 

 strata as post-Cretaceous, at least provisionally. 



In the annual report of the Hayden Survey 

 for 1876, published in 1878, White presented 

 in a lengthy paper the results of his field 

 studies in Colorado for the years 1876 and 

 1877. He still retained the term post-Cre- 

 taceous for the Laramie and in an instruc- 

 tive table (p. 22) showed that he regarded it 

 as the equivalent of the Laramie of King, 

 the Point of Rocks group of Powell, and the 

 Lignitic of Hayden. He defined it' as follows : 



The fact that this series passes insensibly into the Fox 

 Hills group below and into the Wasatch group above 

 renders it difficult to fix upon a stratigraphical plane of 

 demarcation, either for its base or summit. I have there- 

 fore decided to regard this group as essentially a brackish- 

 water one, referring all' strata below that contain any 

 marine Cretaceous invertebrate forms to the Fox Hi.Us 

 group, beginning this series with those strata that con- 

 contain brackish' and fresh water forms, and ending it 

 above with those strata in which the brackish-water 

 forms finally cease. Thus defined, the whole series seems 

 to form one natural paleontological group, as well as to 

 be a sufficiently distinct stratigraphical one, for which I 

 have adopted the name of Laramie group of King. 



The term post-Cretaceous was also employed 

 by Ehdlich 49 in his report on the White River 

 area of Colorado, and by Peale 50 in his work 

 in the Grand (now Colorado) River region. 



The application of the term Laramie was 

 carried farther and farther afield, until ulti- 

 mately it was made to include a vast area in 

 the Rocky Mountain region. When the term 

 was first proposed by King no type locality 

 was mentioned but it was expressly stated to 

 include the lignite-bearing beds lying con- 

 formably above the Fox Hills along the Front 

 Range in northern Colorado and along the 

 west side of the range in eastern and central 

 Wyoming. The term was immediately 

 accepted, though with reservations as to the 

 age represented, by the members of the Hayden 



« U. S. Geo!, and Geog. Survey Terr. Tenth Ann. Bept., for 1876, 

 pp. 77, 109, 1878. 

 » Idem, p. 181. 



