132 Geological Equivalents. 
descends, from south to north, from three thousand three hundred 
feet to one thousand five hundred ; in the Alps it is formed by the 
fir, and is found at five thousand six hundred feet in the northem 
Alps, and at six thousand two hundred in the southern. In the Py- 
renees it is also formed by the fir, and exists between six thousand 
five hundred and six thousand nine hundred feet. In Scandinavia, 
the region of birch is distinguished from that of fir; in the Alps and 
_ Pyrenees, that of fir is distinguished from that of beech and chesnut. 
18, The limit of the Cerealea, in Scandinavia, (60° to 61° N. 
Lat.) is found at two thousand, under the latitude of 70° it descends 
to the se’. In the northern Alps it is found at three thousand four 
hundred, in the southern at four thousand five hundred ; in the north 
ern Pyrenees at four thousand nine hundred, and in the southern, a 
five thousand two hundred. The limit of the region is at two thou 
sand five hundred feet in the southern Alps.” 
- 19. The varieties presented by the animal kingdom are of less 
importance. 
**20. It is not possible to explain by physical causes, the differ- 
ences which characterize the races of men who inhabit the three 
mountainous regions thus brought into comparison.” 
The paper of M. Schouw is accompanied by two lithographi¢ 
plates, which represent the longitudinal and transverse sections of the 
three chains, and also exhibit to the eye many of the results above 
stated. 
The specimen, which this author has given us of the book, which 
will comprehend the whole of his course, must create a lively desire 
for the prompt appearance of the entire work. 
a 
Art. XVI.—Geological Equivalents; by Prof. Amos Eaton.” 
. ReEwative position and mineral constituents, were deemed sufl- 
cient by Werner for determining geological equivalents. As relative 
position is the basis of the science, all other circumstances have al- 
ways been received as auxiliaries only, so far as classification is Cour 
cerned, _ But the frequent displacement of vast fields of strata, theut 
concealment under detritus, their basseting and cuneiform termina 
* The organized remains quoted in this article, have been collected chiefly with! 
the period of the last ten weeks; though a few similar ones had been before examine® 
As I was assisted by several students of the Rensselaer School, {hose who may be 
sirous to review the localities visited and to correct the errors which may be P : 
