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UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



It appears positive that the Fort Union group cannot be separated from 

 the Colorado Lignitic, or rather that they are both united under the Laramie 

 group into a continuous formation. Dr. Hayden has remarked it in the same 

 report when he says that the Lignitic group descends northward along the 

 east base of the Laramie Range, and reappears on its other side about ten 

 miles south of the Union Pacific Railroad. It is therefore continuous. 



