307 
The Formation of the Primary Pocks. 
The preceding observations refer exclusively to the forma- 
tion of the sedimentary beds, in which organic remains are 
enclosed. I shall now proceed to describe the fundamental 
crystalline rocks, on which the sedimentary rocks have been 
deposited, and in which there are no organic remains. 
On reference to the ordinary geological sections, it will be 
observed that the primary crystalline rocks, which have a 
more or less laminated structure, such as the gneiss and ar- 
gillaceous schists, are represented as sedimentary beds, like 
the superincumbent mechanical deposits; and their general 
vertical position has been attributed to a tilting action pro- 
duced by upheavals, &c. During my residence and travels 
near equatorial America from 1834 to 1842, and again from 
1844 to 1848, I had an opportunity of inspecting, surveying, 
and carefully studying the true character of this vertical struc- 
ture of the fundamental crystalline rocks, in ravines, and in 
natural sections, from the surface to 3,000 feet deep. I then 
discovered that this structure did not arise from the subdivision 
of sedimentary beds, but had originated from a semi-crystal- 
line action of the primary base upwards, in the direction of the 
grain ; and that vertical cleavage planes gradually and imper- 
ceptibly became developed in the subterranean base during the 
changes and the transitions of the granites into the schistose 
rocks. I further found, by very extensive surveys across the 
three branches of the Andes, and for some hundreds of miles 
from south to north, that this structure was not only more or 
less vertical, but that it had also a meridional bearing. Having 
fully satisfied myself of this great fact, which, as far as I was 
then aware, had not been noticed before, I referred to the 
observations of others, thinking that such a striking pheno- 
menon could not have escaped attention. 
I naturally concluded that if such great facts as this vertical 
and meridional order in the structure of the primary rocks had 
been observed, the subject would have been pursued, and some 
hypothesis founded thereon. On referring to geological works, 
I found the following observations : — ■ 
Yon Bucli remarks that “the structure and cleavage-planes 
of the laminated granite, gneiss, and schist run in a south and 
north direction, in a position deflecting little from the perpen- 
dicular, in Norway, Sweden, and Finland. . . . The same 
order of structure was observed by M. Boue in Auvergne, and 
in many parts of Spain, Portugal, and Africa.” — “ When I 
arrived on the coast of Venezuela,” says Humboldt, “and 
