HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



25 



2J riiik'S southwest of Norton, Colo.: 



Platanus sp. 



Fieus denveriana Cockerell. 



Populus sp. 



Hicoria antiquora? (Newberry) Hollick. 



Palm rays, gen.? 



Salix angusta? Alex. Braun. 



Ficus denveriana Cockerell. 



Populus sp.? 



Magnolia? 



Lauras? sp., fragments. 



Fraxinus eocenica Les^uereux. 

 Half a mile southeast of Ramah oil prospect, Colo. : 



Lygodium kaulfusii Heer. 



Anemia lanceolata Knowlton. 



Myrica like M. torreyi, but without teeth. 



Ficus sp. cf. F. denveriana Cockerell. 



Laurus sp. 



Populus sp. cf. P. nebrascensis Newberry. 



On bringing the named forms together we 

 have the following list : 



Pteris undulata. 

 Lygodium kaulfusii. 

 Anemia. 



Hicoria antiquora? 

 Salix angusta? 

 Populus nebrascensis. 

 Ficus planicostata. 

 Ficus deijveriana. 

 Platanus haydenii. 



Platanus raynoldsii. 

 Platanus rhomboidea. 

 Vitis olriki. 

 Cissus lobato-crenata. 

 Laurus socialis. 

 Laurus wardiana? 

 Magnolia? 

 Fraxinus eocenica? 

 Viliurnum marginatum. 



As this list stands, and on the assumption 

 that the determinations have been correctly 

 made, no one familiar with the several floras 

 of the Denver Basin would hesitate, I think, 

 to pronounce this a distinctly post-Laramie 

 flora. If we eliminate the six species of which 

 the ideatification is questioned and confine 

 attention to positively determined forms, it 

 follows that only two species from this list — 

 Ficus planicostata and F. denveriana — have 

 been admitted into the Laramie flora as set 

 forth in the present work. As may be seen 

 by consulting the description (p. 131), Ficus 

 planicostata is a wide-ranging form that oc- 

 curs in the Montana, Laramie, Wilco.x, and 

 Denver formations and the beds at Black 

 Buttes, Wyo., while F. denveriana. (see p. 138) 

 is essentially a Denver species, and the evi- 

 dence of its presence in the Laramie consists 

 of a single more or less imperfect leaf from 

 Popes Bluft', near Colorado Springs, the iden- 

 tification of which is properly cjuestioned. 



A further analysis might be made of the 

 forms not specifically named in the above 

 lists; but this is not deemed necessary, as it 

 can be confidently asserted that their affini- 



ties undoubtedly lie with post-Laramie rather 

 than with Laramie species. 



It will thus be seen that, as now under- 

 stood, the plants do not lend support to the 

 suggestion that these beds are of Laramie 

 age, and they have not been included in the 

 present work. If it should idtimately be 

 shown that these horizons are really in the 

 upper part of the Laramie and not in post- 

 Laramie beds, such a result would help to 

 break down the marked distinction now be- 

 lieved to exist between the flora of the Lara- 

 mie and that of overlying beds, but this is a 

 contingency which the writer is not now pre- 

 pared to recognize.*" 



LANCE FORMATION. 



The age and proper allocation of what is 

 now very generally known as the Lance 

 formation has been one of the most active 

 of the storm centers about which the Laramie 

 controversy has been waged. As viewed in 

 retrospect, it appears that much of the dis- 

 cordance that arose was due to the varying 

 weight attached to the several available kinds 

 of paleontologic criteria, as will be made 

 plain in the following exposition. 



The most marked or conspicuous paleonto- 

 logic characteristic of the Lance formation is 

 undoubtedly the presence of the huge dino- 

 saurian reptiles that have been found in it at 

 so many localities, and it is beyond c|uestion 

 that this characteristic did much to direct and 

 stimulate investigation of the formation, which 

 might otherwise have been long delayed. 



The fi.rst collection of remains of the group 

 of horned dinosaurs known as the Ceratopsia 

 was made by F. V. Hayden in the vicinity of 

 Judith River, Mont., about 1855, but the dis- 

 tinctive characters of the group were not dis- 

 covered until more than 30 years later. The 

 material collected by Hayden, consisting of 

 isolated teeth, was described by Joseph Leidy, 

 who tentatively regarded it as of Jurassic 

 (Wealden) age. A fuller discussion of the 

 Judith River problem will be found on page 77. 



The ne.\t in order of discovery was the cele- 

 brated Agathavriuas sylvestris Cope, found in 



89 Since the foregoing pages were written it has heen demonstrated 

 by Lee that the Scranton coal and the beds at a number of locahties on 

 Sand Creek and Coal Creek, east of Denver, are of post-Laramie age. 

 This determination has an important bearing on the age of the beds 

 east of Colorado Springs mentioned in this chapter. The discovery 

 made by Lee is explained on page 1(13. 



