WARD] NATURE AND EXTENT OF THE LARAMIE GROUP. 433 



reux, ill his new work just issued from the press on the "Cretaceous and 

 Tertiary Floras of the Western Territories."^ He here consents, in 

 harmony with the g^eiieral tendency of the time, to drop the term Eocene 

 from the title of this chapter and treat simply of the "Flora of the 

 Laramie group," without, however, surrendering his conviction that that 

 group belongs to Eocene time, which he reasserts, although he now I 

 admits that " the flora of the Laramie group has a relation, remarkably ' 

 well defined, with that of S<5zanne," to the east of Paris, where the plant 

 bearing travertines of the Lac de Killy yield, according to the M.arquis 1 

 Saporta, the oldest Tertiary flora yet discovered. He reviews the re- I 

 cently expressed views of White, Cope, and others, and seems quite j 

 well satisfied with the state of oi)inion at the date of writing with re- 

 spect to the age of the Laramie group. 



NATURE AND EXTENT OF THE LARAMIE GROUP. 



In the foregoing review of oi)inion I have sought to illustrate the 

 history of our knowledge of this remarkable formation of American 

 rocks, and to show how, as that knowledge increased, the wide fluctua- 

 tions which characterized the period of general ignorance and limited 

 information gave way to a gradual convergence of views, an equilibra- 

 tion, as it were, of ideas, which is still going on and tending steadily 

 toward the final settlement of o])iniou in harmonj' with all the facts. 



I have given special prominence to the evidence furnished by animal 

 remains and by stratigrai)liy, purposely leaving that from vegetable 

 remains, generally consistent with itself, undiscussed, because they form 

 the principal subject of this paper and can better be treated by them- 

 selves in a future place and in coiiiiectiou with other problems of greater 

 real importance than that of their geological age. 



One of the advantages of the historical method here employed is that 

 it obviates the necessity of offering any special description of the group 

 under consideration as introductory to the treatment of its flora, the 

 reader being now much better prepared to understand such treatment 

 than any preliminarv explanations of my own could have rendered him. 1 '\V6-V hX.^''*-'*^*^* — 



He perceives, from what has been said, that the Laramie group is an / i i u, L ■ 



extensive brackish-water deposit situated on both sides of the Rocky / v/vt>^ 



sentiiig some 4,000 feet thickness of strata. He can readily see that j— r^ i jv-«l£«.«. 

 when this deposit was made an immense inland sea must have existed Q 

 whose waters occupied the territory now covered by the Rocky MounE^\^ 

 ains. These waters were partially cut off from the ocean by intervening 

 land areas, through which, however, one or more outlets existed com- 

 municating with the open sea at that time occupying the territory of 



Mountains aud extending from Mexico far into the Bi-itish North i .. rvv\.^j«JtAiui. 

 American territory, having a breadth of hundreds of miles and repre- ^*'^***^ 



'\\o f<^' 



'Report of the United States Geological Survey of the Territories (Hayden), Vol. 

 VIII, 18H3, pp. 109-114. 



6 G-EOL 28 





(,.1 •('■>_» 



