222 GEOLOGY OF THE DENVEE BASIN. 



below that at which the fresh-water mollusks were found. In describing 



the Judith River beds it is stated that Messrs. Weed and Stanton have 



found these same brackish-water species on Judith River, above fresh- water 



fauna. This fact shows, then, that these brackish-water forms occur above 

 the stratigraphic break at the buse of the Livingston, and hence they are 

 not competent to decide whether strata containing them are Laramie or 

 post-Laramie, the main question under discussion m this section. 



EVIDENCE OF FOSSIL PLANTS. 



Historical statement. — 'Idle tv])ical 1 Vnver beds of Table Mountain contain 

 one of the largesl and most fully described fossil floras known in this 

 country. Nevertheless, until quite recently, this flora has Keen of little 

 value in discussing the age of the formation containing it, or even the 

 question as to the separation of the Denver and Laramie. In 1889, while 

 describing the " Denver Tertiary formation," the writer gave facts showing 



that while the fossil plants collected at (iolden formed a large part of the 

 SO-called " Laramie flora," it was impossible to ascertain from the published 

 descriptions, from the Labels accompanying specimens in the National 

 Museum, from catalogues, or other published sources, whether the larger 

 part of the species described come from the Laramie coal measures or from 

 the Denver beds. It was then evident that until a very thorough revision 

 of both old and new material, from the Laramie and Denver alike, had been 

 completed, no safe conclusions could he drawn from the fossil floras upon 

 the question of distinguishing the two formations. 



This revision has now been nearly completed, as appears in the sec- 

 tion by Mr. Knowlton, in- Chapter VII, and it is unnecessary to repeat much 

 of the detail showing how the published data concerning the Laramie and 

 Denver floras became so lamentably inaccurate. Hut this history of the 

 fossil plants is so applicable in its moral to the present condition of other 

 fossil evidence that the leading facts will be given. 



More than 1 (ill species of fossil plants from the vicinilx of (iolden were 

 described by the late Leo Lesipieretix, and assigned to the " Laramie flora." 



These plants were collected during several years, by many persons, chiefly 

 by Prof. Arthur Lakes, of Golden, and Professor Lesquereux himself, and 



