Stevenson.] r±i'± [June 18, 



derful. There would be room for wonder if tlie upper flora were not very 

 different from tlie lower one, since the length of time represented by the 

 Middle Cretaceous must have been enormous. Its rocks are limestones, 

 fine shales, and very fine grained sandstones. These certainly were not 

 deposited in haste. What changes in the vegetation were going on 

 during this great period, we have no means of ascertaining, for not a 

 leaf remains to tell the story. We know only that great changes did 

 take place during the interval, since after its close the forms are different 

 from those prevailing before its beginning. But it is very difficult to see 

 how this difference in character is an argument to show that the rocks 

 are Tertiary and not Cretaceous. 



But the plants of this group are insufficient witnesses. Their testi- 

 mony is as bad as that of the Dakota plants. The fucoid, Halymenites 

 major, which Mr. Lesquereux does regard as diagnostic of the Tertiary,* 

 is not a Tertiary fossil. It is Cretaceous or nothing, for whenever it is 

 associated with a marine fauna, whether in New Mexico, Colorado, or 

 Utah, that fatma is Cretaceous. Mr. Lesquereux acknowledges this as 

 satisfactory evidence in one part of the series — why not in the other ? 

 The land plants are in some instances so eccentric in their range as to be 

 of little service. In the Rocky Mountain region there are found seven 

 species which occur also at Nanaimo. Their distribution in the Rocky 

 Mountain region is as follows, according to Mr. Lesquereux : 



Sequoia Langsdorfii, A. Br. Lower Eocene, Upper Miocene. 



Salisburia polymorpJia, Lesqx. , Upper Miocene. 



Satal Qrayana, Lesqx., Lower Eocene. 



Populus mutaMUs, A. Br., Lower Eocene. 



Cinnamomum Reeri, Lesqx., Dakota Group. 



Andromeda Qrayana, Lesqx., Lower Eocene, Upper Eocene. 



Diospyros lancifolia, Lesqx,, Upper Eocene. 



So in the Rocky Mountain region we find the Nanaimo species floating 

 about from the base of the Cretaceous to the top of the Miocene. No 

 doubt the distribution of these species shows that the Nanaimo beds and 

 the Rocky Mountain beds are on the same horizon, and that they are both 

 Lower Eocene as Mr. Lesquereux would have us believe. If they do, the 

 fact must be taken by faith and not by sense. 



As already stated, the occurrence of fresh-water shells or of land shells 

 in any portion of the group is not satisfactory evidence, either for or 

 against the Cretaceous or Tertiary age of the deposit. 



In view of these facts, 



1st. That the series above Cretaceous No. 4, to the top of the Great 

 Lignite Group, is conformable within itself throughout, 



2d. That no change of importance occurred in the general conditions 

 during the formation of this series, 



* See his remarks on " Coalville" in Hayden's Report for 1872, p. — . 



