1846.] Structure of Granitic Mountains. 207 



I hope soon however to see the day when our practical farmers 

 in different sections of the country will perceive the importance 

 of thinking and writing more on their practice, with a view of 

 seeking information and imparting knowledge to each other; by 

 this means, and this only, we may soon establish an American 

 system, however varied may be the climate, soil, or location. 



Dec. 19th, 1845. 



STRUCTURE OF GRANITIC MOUNTAINS. 



The form of granitic mountains is usually conical, sometimes 

 sharply, and sometimes obtusely conical. It is rare that they pre- 

 sent the form of a parabola, or a perfect dome-shaped summit; 

 such, however, is the form of the Brocken, in Switzerland. So 

 perfect and indeed so regularly dome-shaped is this mountain, 

 that a small house upon its summit is distinctly visible at a great 

 distance. 



All the granitic mountains of New York belong to the sharply 

 conical class, and when seen at a distance appear like towering 

 castles. 



In structm-e, or in the internal arrangement of their subordinate 

 masses, a great similarity exists. The Brocken, already referred 

 to, is described by L. Von Buch, as being formed of parallel lay- 

 ers of granite arranged in parabolic curves. The explanation 

 which is given of this singular structure, is, that it was softened 

 by internal heat, and then blown up like a great bubble; and it 

 is supposed to follow from this view, that the granite thus lifted 

 up from below, cannot be considered as belonging to any kind of 

 lava, or as a semi-fluid filling fissures from above, but that it 

 possessed a certain consistency which in most cases was far re- 

 moved fi-om the condition of absolute fluidity; and indeed the 

 beautiful and regular external form which the rock assumes, rend- 

 ers any other assumption improbable.* In our own country, 



• Exposition of Von Buch's views in the Quarterly Journal of the Geol. 

 Society of London, p. 127. 



