AGE OF THE AEAPAHOE AND DENVER. 225 



The floras of the Middle Park and Livingston formations have already 

 been stated to resemble the Denver very closely. 



The Arapahoe formation was found by Mr. Eldridge to contain poorly 

 preserved fossil leaves at a number of localities within tin- Denver region, 

 but none determinable was collected. Bui in the course of the recent 

 collections made for Mr. Emmons by Professor Lakes, a leaf-bearing 

 stratum was found near Sedalia, south of Denver, in what are apparently 

 Arapahoe beds. This local flora contains 19 species, 3 of which arc new: 

 2 an- known elsewhere only in the flora of Carbon, Wyo.; and all of the 

 11 remaining species have been found in the Denver beds. Of the 11 

 Denver species, 7 have no other known distribution, but 5 an- found in the 

 true Laramie. 1 in the Livingston beds, and 1 on .Sand ('reek, east of 

 Denver, in beds whose exact locality is not known. This analysis brings 

 out a strong relationship to the Denver flora and also an affinity with 

 the Laramie, seemingly stronger than that of the Denver Mora for the 

 Laramie. The presence of Carbon species is in the line of the suggestion 

 made elsewhere that the beds of Carbon and some other localities in 

 Wyoming may prove to 1 f Arapahoe age. 



In his summary Mr. Knowlton distinguishes the locality of Sand ('reek 



with 10 species, tor the reason that these plants, all collected 1)Y the members 



of the Hayden survey, come from a locality where the Arapahoe rests on 

 the Laramie (see map), and where both carry fossil plants. The specimens 

 preserved in the National Museum do not satisfactorily indicate the horizon 

 from which they came. It seems probable that a part of them came from 

 the Arapahoe beds and a part from the Laramie. 



conclusions from fossil plants. — From tin- large Denver and Laramie Moras, 

 containing so tew species in common, it would appear that the two epochs 

 were separated by an interval in which the change in vegetation was 

 very important. During this interval the Arapahoe beds were deposited, 

 but present knowledge of the plant life of that epoch is too meager to be 

 of value in correlating that formation. 



The most important conclusion to be drawn from the consideration of 

 the fossil plants applies with equal force to other classes of fossils, namely, 

 that conscientious observation and record of stratigraphic facts concerning 



MON XXVII 1.") 



