HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



17 



and Denver plants have sliown tliem to be 

 essentially Tertiary in type. 



In 1892 Cross "" briefly reviewed the rela- 

 tions of the Arapahoe and Denver formations 

 of the Denver Basin and also enumerated 

 additional localities in the Huerfano Basin, 

 Gunnison County, the Yampa River region, the 

 Animas River region, Middle Park, and else- 

 where, in which identical or similar strati- 

 graphic relations had been suggested. He 

 discussed at length the conflicting paleonto- 

 logic evidence of the age of the lake-bed 

 deposits and concluded as follows: 



The writer wishes to advocate the restriction of the term 

 Laramie, in accordance with its origins,! definition, to 

 the series of conformable beds succeeding the marine 

 Montani Cretaceous, and the grouping of the post-Laraniie 

 lake beds described, with their demonstrated equivalents. 

 in another series to which a comprehensive name shall 

 eventually be given. * * * The question as to 

 whether the series shall be referred to the Creticeous or to 

 the Eocene can not be finally settled until the various 

 conflicting elements of the evidence have been adjiisted 

 on a basis of further and more exact information. 



Later in the same year Cross "' published an 

 article on the post-Laramie beds of Middle 

 Park, as an amplification of the previous brief 

 notice. In this article he showed that the 

 large area referred to the "Lignite" or Laramie 

 was occupied by a thick series of mainly 

 andesitic rock resting unconformably on marine 

 Cretaceous beds, with no evidence that the 

 Laramie had ever been present. These beds, 

 which he called the Middle Park beds, were 

 correlated with the Denver on account of the 

 lithologic similarity and the identity of the 

 contained flora. 



The publication of the Denver Basin mono- 

 graph by Emmons, Cross, and Eldridge "^ 

 was delayed until 1896, and in many ways the 

 delay was perhaps of advantage, for it per- 

 mitted the incorporation and discussion of 

 many important facts that had in the meantime 

 been made available regarding the strati- 

 graphic and other relations of the determined 

 or supposed correlatives of the formations 

 here under discussion. The Laramie, Arapa- 

 hoe, and Denver formations of the Denver 

 Basin were, of course, described in detail, and 

 the unconformable relations between the 

 Laramie and overlying Arapahoe were espe- 



wCro-SS, Whitman, Post-Laramie deposit.? of Colorado: .'ira. Jour. 

 Soi., 3d ser., vol. 44, pp. 19-42, 1892. 

 5" Cross, Whitman, Colorado S;i. So-. Pro-., vol. 4. pp. 192-21.3. 189.2 

 M U. S. Geol. Survey Man. 27, 1896. 



cially made plain. The magnitude of the time 

 interval represented by the unconformity was 

 insisted upon as of major importance in Rocky 

 Mountain geology. 



The Arapahoe and Denver formations were 

 in this monograph referred to the Cretaceous 

 out of deference to the views of the vertebrate 

 paleontologists, as it had been found that the 

 vertebrates appeared lo be much more nearly 

 allied to Mesozoic than to Cenozoic types. 

 The lithologic and stratigraphic relations of 

 these formations, as well as a very full dis- 

 cussion of the several lines of palcontologic 

 evidence, are given by Cross, who prepared this 

 portion of the volume. In the light of sub- 

 sequent development it has been found that 

 many of his queries and adumbrations have 

 had a wide and increasingly important appli- 

 cation. 



For ten years after the publication of the 

 Denver Basin monograph little active work 

 was prosecuted in this region, though investi- 

 gations in adjacent or more remote areas were 

 found to have a more or less direct bearing on 

 the problem here involved. In 1907 A. C. 

 Veatch,"^ from studies in Carbon County, ' 

 Wyo., was led to question the validity of the 

 current application of the term Laramie. He 

 endeavored to prove that Carbon, Wyo., was 

 intended by King to be the type locality for the 

 Laramie. In this vicinity Veatch discovered 

 that in the supposedly continuous Laramie 

 section there is a profound unconformity 

 similar to that found by Cross in the Denver 

 Basin, and as the beds at Carbon studied and 

 described by the members of the King Survey 

 are all above this break he contended that the 

 name should properly be applied only to these 

 beds and not to the beds that are conformable 

 to the Cretaceous section. Veatch further 

 held that the delimitation of the Arapahoe 

 and Denver constituted a virtual redefinition 

 of the Laramie. 



Replies to this paper were made by Cross "* 

 and Peale,"^ and it is sufficient to state that 

 the view advocated by Veatch has not been 

 adopted. Cross especially reviewed the facts 

 relating to the application of the term, hold- 



M On the origin and definition of the geologic term Laramie: Am. Jour. 

 Sci., 4th ser., vol. 24, p. 18, 1907; expanded under the same title in .lour. 

 Oeology, vol. 1.5, p. 526, 1907. 



"Cross, Whitman, The Laramie formation as the Shoshone group: 

 Washington Acad. .Sci. Proc, vol. 11, pp. 27-4.5, 1909. 



» Feale, A. r., Oil the application of the term Laramie: .\m. Jour.Sei., 

 4th ser., vol. 28, pp. 45-38, 1909. 



