577 



a .) The Longitudinal axis of the whole chain. 

 p.) The line that divides the waters (divortia 

 aquarum). 



y.) The line of ridges or elevation passing 

 along the maxima of height. 



5.) The line that separates into horizontal 

 sections, two contiguous formations. 



t.) The line that follows the rents of stra- 

 tification. 



This distinction is so much the more necessary, 

 as there exists probably no chain on the globe 

 that furnishes a perfect parallelism of all these 

 directing lines. In the Pyrenees, for instance, 

 «, j3, y do not coincide, but 2 and e (that is, the 

 different bands of formations which come to 

 light successively, and the direction of the 

 strata) are sensibly parallel to a, or to the di- 

 rection of the whole chain *. We find so often 

 in the most distant parts of the globe, a perfect 

 parallelism between a and f, that it may be sup- 

 posed that the causes which determine the di- 

 rection of the axis (the angle under which that 

 axis cuts the meridians), are generally linked 

 with causes that determine the direction and 



* The direction of the longitudinal axis a in the Pyre- 

 nees, and that of the formations which appear successively 

 at the surface of the soil, as in long bands, are N. 68° 73* 

 W. Now, as the line of the maxima of height y, is not pa- 

 rallel with the axis a, it results from the fine observations of 

 MM. Palassou, Ramond and Charpentier, that it must ne- 

 cessarily pass by very different formations. 



VOL. VI. 2 Q 



