,342 GEOLOGICAL SURVEY OF THE TERRITORIES. 



To my opiuion, this fact is of groat weight in discussing the question 

 of the age of these formations. For the presence of deep marine species 

 iu strata overlying remq^ns of more recent ones indicates a local sub- 

 sidence which should be considered as an exceptional case, unimportant 

 indeed iu comparison to the persistence of general characters. Beds of 

 lignite of Eocene age mny have been formed at a higher level or before 

 this supposed local subsidence. And, of course, as resulting from it and 

 from a subsequent upheaval, fucoidal remains mixed with Cretaceou* 

 shells ; and Cretaceous saurian bones, too, with brackish mollnsks and 

 dicotyledonous leaves of the Eocene, would be in a position, if not ex- 

 actly normal, at least easily explainable. 



Professor F. B. Meek's letter furnishes another point of evidence on 

 the same question, in his remarks on a peculiar species of plant which 

 he describes, and of which he sent me numerous specimens. It is that 

 fucoidal plant, Ilalhncnites, which has been mentioned already as one of 

 the essential characteristic species of the Eocene. He writes that he 

 found it at Coalville, at least 1,000 feet below well-marked Cretaceous 

 beds; that it ranges also through most of the Cretaceous beds of Bear 

 Eiver, and through the whole of the Bitter Creek series, nearly up to the 

 Black Butte bone-level ; that he saw it too at Carbon and in the Creta- 

 ceous beds of Fort Steele. The range of this species is indeed from the 

 base of the Lignitic to its upper strata, those of Carbon and of Evans- 

 ton, and, therefore, we have at Bear Creek and Coalville shallow marine 

 plants and lignite-beds under Cretaceous remains. These last character- 

 istic documents, or the remains of Cretaceous age, are local, merely in 

 isolated patches ; the others are recognized over the w^hole extent and 

 the whole thickness of the Lignitic formations. The question is, there- 

 fore, reduced to this: Shall we admit as Cretaceous all these land forma- 

 tions bearing from top to bottom evident Eocene characters, on account 

 of some isolated Cretaceous deposits locally spread over them ; or shall 

 we consider the whole as presenting general characters positive enough 

 to force its separation into a new group and call it Eocene ? In this case 

 we should have to consider the abnormal disposition of Cretaceous re- 

 mains as resulting from local disturbances which are observable every- 

 where in this central basin, both by repeated undulations, pierced here 

 and there by eruptive rocks, bearing irrevocable marks of the diversified 

 action of the forces which have modified its surface. 



As 1 have not visited the localities. Bear Eiver and Coal Creek, where 

 the abnormal distribution of the strata has been remarked, the above 

 arguments may be considered objectionable. But how can we dispose 

 of an evidence, forced by comparison between our Eocene strata and 

 those of the Carboniferous epoch, where, as remarked before, we recognize 

 facts similar to those now under discussion ? We do not and cannot call 

 the coal measures either Devonian or Permian, on account of some fossils 

 mixed iu their strata, and identical to species of these different formations. 

 Would it be rational to admit that the Eocene shells and Eocene plants 

 under the strata bearing Cretaceous fossil-remains may be so-called 

 Eocene colonies, decended into the Cretaceous, that the lignite-beds 

 underlying them represent an escaped member of the Eocene, bearing, 

 as it does, in its flora, its compounds, &c., Eocene characters ; and that 

 these Eocene members have become of Cretaceous age by the only reason 

 that some Cretaceous fossils are seen over them ? As legitimate would 

 it be, I think, to adaiit our present epoch as Cretaceous from the animals 

 of Cretaceous types brought up by deep soundings from the bottom of 

 our seas. But this subject has to be considered under another point of 

 view. 



