374 GEOLOGICAL SUEVEY OF THE TEERITORIES. 



land character, a Tertiary formation, therefore giving the precedence to 

 the fossil flora over the fossil fauna for the determination of the age of 

 this formation. It is, then, evident that the fossil plants have some 

 weight and must decide. 



7th. This brings me to the essential question which has to be exam- 

 ined in considering the relation of the age of the fossil plants of the 

 Lower Lignite of the Eocky Mountains. 



Though the flora is evidently related to that of the Tertiary of Europe 

 by a large number of its species, it is, however, difficult to point out with 

 uncontestable evidence to what stage of this Tertiary the relation is the 

 more intimate. To come to an understanding on this subject, we have 

 to compare the American fossil species with those known as yet from 

 the publications of European authors, and at once are met with a 

 scarcity of materials, especially from the Lower Tertiary strata or the 

 Eocene, to which, considering the position of the Lignitic,its flora should 

 be especially related. The Tertiary of Europe seems to have been, as 

 expressed by Dr. Ettinghausen in his Contributions to the Eadoboj 

 Flora, " a kind of universal vegetable repository, representing types of all 

 the regions of the world ; a seminarium, which hereafter dispersed its 

 offsprings over the whole surface of the earth." This conclusion is not 

 my own. I should only say that the European Tertiary formations 

 have been the recipient of species representing an heterogeneous vege- 

 tation, type of multiple and local changes. But this matter is out of the 

 subject f we have only to record the fact that, so mixed in their fades 

 are the floras of the Tertiary basins of the Old World that as yet no 

 reliable delimitation has been established for the stages which they 

 represent.* 



In considering the characters of our Lower Liguitic flora, a critic has 

 asserted that its genera are all, as well as the species, without relation 

 to Eocene vegetable types of Europe, quoting as a proof of his assertion 

 the flora of Mount Bolca, and that of Shepey in England. This last 

 flora is merely known by fruits whose forms or species have been de- 

 scribed and figured by Bowerbank, and w'hich are heaped in prodigious 

 quantity in the so-called London clay of England. This Eocene tlora, 

 however, cannot be taken for America any more than it has been for 

 Europe as a point of comparison, for it has no leaves, and its fruits, of 

 various and uncertain affinity, have as yet not been found elsewhere in 

 the Tertiary of Europe, except a few Nepadites, merely mentioned (not 

 described yet) from the Eocene of Mount Bolca. These Shex^ey fruits, 

 as Heer remarks, are not characteristic of the formation, even say noth- 

 ing in regard to the climate of the locality where they are found, as, from 

 appearance, they have been floated down some river for a great distance, 

 and are analogous to present deposits of this kind at the mouth of the 

 Ganges. The Eocene flora of the Isle of Wight, at Alumbay, is repre- 

 sented by numerous leaves of Aralia, Daphnogene, Ficus, Zizyhus, Ccesal- 

 ipinia, &c., which, according to Heer, have such a marked tropical and 

 subtropical character that the fruits of Shepey may have been derived 

 from the plants of this locality. These Alumbay leaves, to quote the 

 same authority, are similar to species of Mount Bolca ; three species are 

 identified as the same, and three others are closely related. But also a 

 number of them are Miocene; as, Quercus loncMtis ; Laurus primi- 

 genia; Myrica [Diandra] acutiloda ; Cassia phaseolites ; or four species, 



* Since writiug this, the third and last volume of W. P. Schimper, Palontologie 

 veg^iale, has appeared. The author, considering the vegetable groups of the Tertiary, 

 divides the formation in the five following stages : Paleocene, intermediate to the Cre- 

 taceous and Tertiary ; Eocene, OUgocene, Miocene, and Pliocene. The relation of our Lig- 

 uitic vegetation seems to he with the Oligocene. 



