334 USPALLATA PASS. ; [crap. xv. 
The'scenery thus far was very uninteresting, compared with 
that of the Portillo pass. Little can be seen beyond the’ bare 
walls of the one grand, flat-bottomed valley, which the road fol- 
lows up to the highest crest. The valley and the huge rocky 
mountains are extremely barren: during the two previous nights 
the poor mules had absolutely nothing to eat, for excepting a few 
__ low resinous bushes, scarcely a plant can be seen. In the course 
of this day we crossed some of the worst passes in the Cordillera, 
but their danger has been much exaggerated. I was told that if 
I attempted to pass on foot, my head would turn giddy, and that 
there was no room to dismount; but I did not see a place where 
any one might not have walked over backwards, or got off his 
mule on either side. One of the bad passes, called las Animas 
(the Souls), I had crossed, and did not find out till a day after- 
wards, that it was one of the awful dangers. No doubt there are 
many parts in which, if the mule should stumble, the rider would 
be hurled down a great precipice; but of this there is little 
chance. I dare say, in the spring, the “ laderas,” or roads, 
which each year are formed anew across the piles of fallen 
detritus, are very bad; but from what I saw, I suspect the real 
danger is nothing. With cargo-mules the case is rather different, 
for the loads project so far, that the animals, occasionally running 
against each other, or against a point of rock, lose their balance, 
and are thrown down the precipices. In crossing the rivers I 
can well believe that the difficulty may be very great: at this 
season there was little trouble, but in the summer they must be 
very hazardous. I can quite imagine, as Sir F. Head describes, 
the different expressions of those who have passed the gulf, and 
those who are passing. Inever heard of any man being drowned, 
but with loaded mules it frequently happens. The arriero tells 
you to show your mule the best line, and then allow her to cross 
as she likes: the cargo-mule takes a bad line, and is often lost. 
April 4th—From the Rio de las Vacas to the Puente del 
Incas, half a day’s journey. As there was pasture for the mules, 
and geology for me, we bivouacked here for the night. When 
one hears of a natural Bridge, one pictures to oneself some deep 
and narrow ravine, across which a bold mass of rock has fallen; 
or a great arch hollowed out like the vanit ofa cavern. Instead 
of this, the Incas Bridge consists of a crust of stratified shingle, 
