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 northern 

 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 sea. 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, at 

 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 lithographic 

 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. 



Art. XVI. — Geological Equivalents ; by Prof. Amos Eaton.* 



Relative position and mineral constituents, were deemed suffi- 

 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 con- 

 cerned. But the frequent displacement of vast fields of strata, their 

 concealment under detritus, their bassetjng and cuneiform termina- 



* The organized remains quoted in this article, have been collected chiefly within 

 the period of the last ten weeks; though a few siniijar ones had been before examined. 

 As I was assisted by several students of the Rensselaer School, those who may be de- 

 sirous to review the localities visited aud to correct the errors which may be presumed 



