348 GEOLOGICAL SUKVEY OF THE TERPJTORIES. 



eating such affinity with leaves also very abundant at Black Butte, that 

 it is as yet uncertain if the American form does not represent a mere 

 variety of the same, differing only by the larger size of the leaves. We 

 have at Golden Qnercns angustiloha, Al. Br., described by Heer from 

 the Bornstaedt Eocene, and in the flora of the same locality, as in that 

 of Golden, a remarkable predominance of species of Ficns and of Cinna- 

 momuni, primitive types of the Tertiary of Europe. Some of these 

 pass, with the Sabal species, into the Miocene; for, of course, the Tertiary 

 formations, as land formations, removed from the influence of prolonged 

 submersion in deep marine water, have, like the Carboniferous, a per- 

 manence of the types of their flora, marked by a number of species 

 identical in the groups even of the more remote stations. This answers 

 the observations made on the vegetable species already published in Br. 

 Hayden's reports, and which European authors are disposed to consider 

 as Miocene, from the number of leaves of our Eocene flora, not only 

 homologous, but identical, with Miocene species of Europe. 



This comparison might be pursued farther and with more details. 

 These remarks, however, cannot be indefinitely prolonged. Those who 

 may desire to compare more precise points of correlation or of differences 

 between the flora either of our Eocene and that of the Tertiary of 

 Europe, or of the different strata of the Lignitic at various localities, 

 will find suificient materials for this task in the table of distribution 

 which closes the descriptive part of the fossil flora of this rejiort. 



THE AMERICAN EOCENE IDENTICAL WITH THAT OF EUROPE BY GENERAL 



* CHARACTERS. 



I do not believe that the divisions of our geological groups have to be 

 controlled by European classifications. It is advisable, however, 

 especially on account of the diversity of the conclusions indicated by 

 botanical and animal paleontology, to mention still a few points of 

 analogy remarked in the distribution and composition of the Eocene of 

 both continents. 



The Flysh or Eocene of Switzerland is mostly a compound of shales, 

 here and there interlaid by sandstone strata of great thickne^ and 

 even passing locally to massive sandstone, wher^ the slate-beds disap- 

 pear. This formation extends all along the northern base of the Alpine 

 chain in different degree of thickness, in proportion to the amount of 

 denudation to which it has been exposed. It enters the valleys, especially 

 borders them, in constant and immediate superposition to the Creta- 

 ceous. On the northern base of the same chain, it is present, too, in 

 basins of limited extent, where the Upper Cretaceous strata have been 

 left for its support. The various strata of this Eocene formation are, 

 according to their vicinity to x)rimitive rocks, changed by heat to a cer- 

 tain degree. And the top of these measures is overlaid hy a conglomeratic 

 comijound of materials derived from rods of all the older formations, all 

 rolled pchhles, and in pieces varying in size from that of a. walnut to that of 

 thejist.* In this formation, too, valuable beds of lignite are found: and 

 these, though not as richly developed as in the Eocene of this conti- 

 nent, have sometimes a thickness of C feet, and have furnished com- 

 bustible materials for a long time. The lignite of Niederhorn, 5,700 feet 

 above the sea, has been worked since the former century, and is now 

 used at Bern for the production of illuminating gas. The Eocene group 



* Herr Urwelt der Schweitz, p. 24L 



...J 



