140 SKETCH OF THE LIFE AND ACHIEVEMENTS 



and arrived, August 17th, in about the centre of 

 Asia, north of the Dsaisang sea. 



On his return to the fortress of Ust-Kamenoi- 

 gorsk, Humboldt observed on the lonely shores 

 of the river Irtisch, in an expanse of more 

 than 16,000 feet, enormous masses of granite 

 in an horizontal position, underlaid by clay- 

 slates, parts of whose strata appeared in per- 

 pendicular position, and partly at an angle of 

 85 degrees. This phenomenon became of great 

 importance to Humboldt, with reference to the 

 formations of granite. 



From the fortress above named the travellers 

 journeyed through the steppes of Ischim towards 

 the South Ural; visited Semipalatinsk, Omsk, 

 &c., and arrived at Mjask. From this place 

 Humboldt undertook several excursions in the 

 environs ; and discovered in this district, on a 

 small space, and only a few inches below the 

 surface, three pieces of solid gold. Continuing 

 his journey southward, he arrived at Orsk, where 

 he examined the noted strata of green jasper, 

 and collected other valuable material for geolo- 

 gical investigations on the river Jaik, which 

 broke through the mountain- chain in a north- 

 western direction. 



Humboldt pursued his journey to Orenburg, 

 where he arrived by way of Gruberlinsk, on 



