Investigations and Writings of Baron Humboldt, 219 
along with gold sand, near the iron-works of Bissersk, at the 
small stream of Poludennaja, which falls into the Kama, after 
having previously joined the Tschussoyaja. According to 
the accounts given by Von Engelhardt,* it is probable, 
although by no means certain, that the rock in which these 
diamonds originally occur is a granular dolomite. 
In the course of the same journey, a multitude of remark- 
able facts on the geognostical constitution of the Ural Moun- 
tains was collected, and accurate determinations made regard- 
ing their mountain rocks; which will be very beneficial for 
our knowledge of the rocks occurring near us at home, and an 
account of which is now in preparation by Gustay Rose.+ 
The journey was continued across the Ural by Tobolsk into 
the valley of the Irtisch, and to the frontiers of China. 
~ On the western declivity of the Altai Mountains, Hum- 
boldt discovered an extremely remarkable geognostical fact. 
On the lofty rocky banks of the Irtisch, between Bucktarma 
and Ust-Kamenogorsk, the granite not only breaks through 
the clay-slate, as it frequently does, more or less distinctly, 
in England, Scotland, France, and Germany, but it spreads 
itself horizontally over the surface of the clay-slate for dis- 
tances of several German miles in length. By means of this 
important discovery, we have attained a convincing proof of a 
kind which we did not previously possess, of the volcanic 
origin of granite, and of its actually having, at former times, 
flowed over large tracts of country. 
One of the most valuable results of the same journey is the 
delineation of the connection of the mountain chains in the 
interior of Asia, which was derived from the numerous obser- 
vations made on the subject. Upon this was founded the re- 
markable observation, that, in the interior of the Asiatic conti- 
nent, and partly at distances of upwards of 100 German miles 
from the coast of the sea, there are volcanos of considerable size, 
and still in a state of continued activity, a fact of which we 
had previously not a single example, and which we were for- 
merly often inclined to deny, from theoretical grounds, on 
| SEPT URPOSE Sasa eae A kaeeh ie 0 lar os dee 
* Poggendorff’s Annalen, xx. p, 524, and xxxi, p- 608, 
t Since published. 
