Forms of Mountains as connected with Cleavage. 7 



One side of each peak is formed by the surfaces of the exposed 

 strata, the other side by the cleavages of the strata, and from 

 the latter side the fragments chiefly fall. The debris, discharged 

 from the bottom of the hollow, which separates two contiguous 

 peaks, assumes the form of a cone ; and hence, in mountains of 

 this character, we sometimes see a row of conical masses of rock 

 in place, and below them a corresponding row of cones of debris 

 issuing from the intervening hollows. In this, as well as in the 

 preceding case, the largest fragments fall to the bottom of the 

 slope, and, in both cases, the angle of inclination approaches 45°. 



This second form of ruined mountains is less obvious than the 

 first, because, to perceive it, it is necessary that the observer 

 should look along the planes of stratification and cleavage, which 

 he can do only from certain points of view. It is often found 

 in the slate on each side of the Rhine in Germany, and may be 

 discerned not only in the bare rocks, but in hills covered with 

 vegetation. Thus, at Bad-Ems, we see it in the beautiful 

 wooded eminence on which the Moos-hiitte is erected, when we 

 stand on the opposite side of the Lahn. 



The Acute Cone (as we may call this form of debris) often 

 exhibits, towards its summit, an approach to a spiral figure, 

 arising from the obliquity of the ravine to the mountain side, 

 down which it discharges its loose contents. 



(The drawing, Fig. 2., shows part of a mountain on the south side of 

 the Col de la Seigne, on the confines of Savoy and Piedmont, with 

 a series of peaks, intervening hollows, and cones of debris. Fig. 3. 

 shows the modification of the Acute Cone, arising from the obli- 

 quity of the ravine to the mountain side.) 



Rocks, which are either not at all or less distinctly stratified, 

 and the masses of debris emitted from them, assume forms, ac- 

 cording to circumstances, more or less approaching those which 

 have been described. Nothing is more common than to find a 

 ravine in the steep face, not only of schistose rocks, with an in- 

 ternal rhomboidal structure, but of granite, gneiss, mica- slate, 

 and other primitive rocks, and even of stratified limestone, grit, 

 or conglomerate : in all such cases, the earth and stones, dis- 

 charged from the ravine, will make an Acute Cone. If, on the 

 other hand, the unstratified rocks rise in long walls, as is often 

 the case with basalt and greenstone in particular, their debris wil^ 

 form a regular talus. Nevertheless, the two forms of mountain 



