398 PASSAGE OF COKDILLEBA. March, 1835. 



suppose that the animal fell with its head downward into 

 a hole, when the stratum was continuous, and that after- 

 wards the surrounding parts were removed by the thaw. 



When nearly on the crest of the Portillo, we were en- 

 veloped in a cloud which was falling, under the form of 

 minute frozen spicula. This was very unfortunate, as it con- 

 tinued the whole day, and quite intercepted our view. The 

 pass takes its name of Portillo from a narrow cleft or door- 

 way on the highest ridge, through which the road passes. 

 From this point, on a clear day, those vast plains which 

 extend from the base of the mountains towards the Atlantic 

 can be see a. We descended to the upper limit of vegetation, 

 and found good quarters for the night under the shelter of 

 some large fragments of rock. We here met some passen- 

 gers, who made anxious inquiries about the state of the 

 road. Shortly after it was dark, the clouds suddenly 

 cleared away ; and the eflfect was quite magical. The great 

 mountains, bright with the full moon, seemed impending- 

 over us on all sides, as if we had been buried at the bottom 

 of some deep crevice. One morning also, very early, I wit- 

 nessed the same striking effect. As soon as the clouds were 

 dispersed, it froze severely; but as there was no wind, we 

 slept very comfortably. 



The increased brilliancy of the moon and stars at this ele- 

 vation, owing to the perfect transparency of the atmosphere, 

 was very remarkable. Travellers having observed the dif- 

 ficulty of judging heights and distances amidst lofty moun- 

 tains, have generally attributed it to the absence of objects of 

 comparison. It appears to me that it is fully as much owing 

 to this transparency, confounding different distances, and 

 partly, likewise, to the novelty of an unusual degree of fa- 

 tigue arising from a little exertion, — habit being thus op- 

 posed to the evidence of the senses. I am sure that this 

 extreme clearness of the air gives a peculiar character to the 

 landscape ; all objects appearing to be brought nearly into 

 one plane, as in a drawing or panorama. The transparency 

 is, I presume, owing to the equable and nearly perfect 



