296 M. Humboldt on Iwo Attempts to ascend CJamhorazo. 



Bonn. The slaggy masses of the Yana-Urcu altered by a very 

 active fire, are indeed extremely liglit, but proper pumice- 

 stone has not been thrown out there. The eruption has taken 

 place through a grey, irregularly stratified mass of dolerite, 

 which here forms the table-land, and resembles the rock of 

 Penipe (at the foot of the volcano of Tungurahua) where 

 syenite and mica-slate containing garnets, have been broken 

 through. On the eastern side of the Yana-Urcu, or rather at 

 the foot of the hill towards Lican, the natives conducted us to 

 a projecting rock, an opening in which resembled the mouth of 

 a forsaken gallery. Here, as well as at the distance of ten feet, 

 there is heard a violent subterranean noise, which is accom- 

 panied by a current of air, or subterranean wind. The cur- 

 rent of air is much too weak to admit of the noise being attri- 

 buted to it. The noise certainly arises from a subterranean 

 brook, which is precipitated downwards into a deep hollow, 

 and through its fall occasions a motion in the air. A monk, the 

 priest at Calpi, had, with the same idea, some time before, con- 

 tinued on the gallery at an open fissure to procure water for 

 his village. The hardness of the black augite rock probably 

 interrupted the work. Chimborazo, notwithstanding its enor- 

 mous mass of snow, sends down into the lable-land such insig- 

 nificant brooks of water, that it may be presumed the greater 

 part of its water flows through clefts to the interior. In the 

 village of Calpi itself also, there was formerly heard a great 

 noise in a house that had no cellar. Before the celebrated 

 earthquake of the 4th February 1797, there sprang forth a 

 brook in the south-west of the village, at a deeper point. Many 

 Indians considered this brook as a part of the water that flows 

 under the Yana-Urcu. But since the great earthquake, this 

 brook has again disappeared. 



After we had passed the night at Calpi, which, according to 

 my barometrical measurement, lies 9720 feet (1620 toises) 

 above the sea, we began, on the morning of the 23d, our pro- 

 per expedition up Chimborazo. We attempted to ascend the 

 mountain on the SS. E. side, and the Indians who were to at- 

 tend us as guides, but of whom but a few had ever reached the 

 limit of perpetual snow, gave this course the preference. We 

 found Chimborazo surrounded with great plains, which rise, 



