126 GEOLOGICAL MEMOIRS. 



VI. On the Form of Granitic Rocks, and the Structure of 

 Granite. By L. Von Buch, &c. 



[Read before the Berlin Academy of Science, Dec. 15. 1842.] 



[The paper read by M. Von Buch on this occasion involves two 

 subjects, namely, an expression of opinion and a record of ob- 

 servations concerning the structure of granitic masses, affording 

 an explanation of the frequently described phenomenon of strati- 

 fication in granite, and an account of a journey into Sweden, in 

 which he pursued other investigations on the granite and gneiss of 

 that country. The present notice is confined to the former 

 subject.] 



No object can be more striking than the beautiful bell- shaped 

 form of the Brocken, as this noble mountain, towering above all 

 that surround it, presents itself to the traveller who is approaching 

 it from Elbingerode by way of Schierke. Nothing disturbs the 

 perfect regularity of its parabolic surface, and a small house at the 

 top, that would be undistinguishable on other mountains, is here a 

 prominent object, standing out like a little wart from the surface. 

 From other sides also, the same appearance is preserved, and the 

 dome is so perfect, that during the ascent the actual summit cannot 

 be seen until it is attained. 



So completely is this dome-like shape preserved that, if the 

 mountain were not accessible, it would be thought smooth and 

 almost polished, and that therefore it could not be ascended. 

 It is then with no little astonishment that we find, on actually 

 reaching it, a wild and desolate waste rather than a smooth mirror 

 surface. The whole is covered with innumerable blocks in such a 

 manner that the spaces between them require constant attention 

 from the climber lest he should fall into them, and these blocks 

 are heaped upon another, especially near the foot of the mountain, 

 without the slightest appearance of order. 



This great covering with blocks is common to all ellipsoidal 

 granite which, like the Brocken, has been lifted above the 

 neighbouring formations. At Ramberg — a spur of the Brocken, 

 they are so abundant and assume such fantastic forms as to be 

 called " The DeviVs Mills" in the ancient legends of the country. 

 In other places, as the Sturmhaube in Silesia, in the Odenwald, 

 and in the Schwartzwald, they are called seas of rocks (Felsen- 

 Meere), and at Mount Parnassus they are known as Daimonotona, 

 or " DeviVs Floors." 



These two extremely general phenomena, the regularly circular 

 form of granitic mountains, and the breaking up of the surface 

 into millions of blocks, appear to depend on one another in some 

 necessary relation. That the granite must be looked upon as a 

 great bubble, even where most extended and far less beautifully 

 exhibited than in the Brocken, is generally admitted by geologists ; 



