whence there was no exit; in a more humid climate the
water flowing from the lake would soon have hollowed a
channel in the soft strata, and thus converted the depression
of the soil into an ordinary valley. There is reason to believe
that the whole of these great plains have been raised above
the level of the sea within a recent geological period. May
we not then consider the salinas as the receptacles of the
washings of the sedimentary strata ? On this idea we understand
their absence where the land is granitic. It is
manifest that these great natural evaporating dishes can only
occur where the amount of annual rain is small.*
To the northward of the Rio Negro, between it and the
inhabited country near Buenos Ayres, the Spaniards have
only one small settlement, recently established at Bahia
Blanca. The distance in a straight line to the capital is very
nearly five hundred British miles. The wandering tribes of
horse Indians, which have always occupied the greater part of
this country, having of late much harassed the outlying
estancias, the government at Buenos Ayres equipped some
time since an army under the command of General Rosas
for the purpose of exterminating them. The troops were now
encamped on the banks of the Colorado; a river lying about
eighty miles to the northward of the Rio Negro. When
General Rosas left Buenos Ayres, he struck in a direct line
across the unexplored plains : and as the country was thus
pretty well cleared of Indians, he left behind him, at wide
* A lm o s t e v e ry c ir c um s ta n c e h e r e m e n tio n e d , o c cu rs in th e s a lt lak e s
n e a r th e b o rd e rs o f th e C a sp ia n . T h a t c o u n try , lik e P a ta g o n ia , a p p e a r s
to h a v e b e e n r e c e n tly e le v a te d a b o v e th e w a te rs o f th e s e a . P a lla s s ta te s
t h a t th e s a lt la k e s o c c u p y sh a llow d e p re s s io n s in th e s te p p e s ; t h a t th e
m u d o n th e b o rd e rs in e v e ry case is b la c k a n d f e tid ; t h a t b e n e a th tlie
c ru s t o f .sea s a lt, s u lp h a te o f m ag n e s ia o c cu rs, im p e rfe c tly c ry s ta lliz e d ;
t h a t th e m u d d y sa n d is m ix e d w ith le n tils o f g y p sum . W e h a v e b e fo re
s ta t e d t h a t th e s e lak e s a r e in h a b ite d b y sm a ll c ru s ta c e o u s a n im a ls ; a n d
flam in g o e s (E d in . N ew P h ilo s . J o u r ., J a n . 18 3 0 ) lik ew ise f r e q u e n t
th em . As th e s e c irc um s ta n c e s , a p p a r e n tly so triflin g , o c c u r in tw o dist
a n t c o n tin e n ts , w e m ay fe e l s u re th e y a re th e n e c es s a ry re s u lts o f some
c om m o n c a u s e .— S e e Pallas’s Travels, 1793 to 1794, p . 129 134.
intervals, a small party of soldiers, with a troop of horses
(a posta), so as to be enabled to keep up a communication
with the capital. As the Beagle intended to call at Bahia
Blanca, I determined to proceed there by land; and ultimately
I extended my plan so as to travel the whole way by
the postas to Buenos Ayres.
A u g u s t 1 1 t h .— Mr. Harris, an Englishman residing at
Patagones, a guide, and five Gauchos, who were proceeding
to the army on business, were my companions on the journey.
The Colorado, as I have already said, is nearly eighty
miles distant: and as we travelled slowly, we were two days
and a half on the road. The whole line of country deserves
scarcely a better name than that of a desert. Water is found
only in two small wells : it is called fresh; hut even at this
time of the year, during the rainy season, it was quite brackish.
In the summer this must be a distressing passage ; for now
it was sufficiently desolate. The valley of the Rio Negro,
broad as it is, has merely been excavated out of the sandstone
plain; for immediately above the bank on which the
town stands, a level country commences, which is interrupted
only by a few trifling valleys and depressions. Every
where the landscape wears the same sterile aspect; a dry
gravelly soil supports tufts of brown w'ithered grass, and low
scattered bushes, armed with thorns.
Shortly after passing the first spring we came in sight of
a famous tree, which the Indians reverence as the altar of
Walleechu. It is situated on a high part of the plain, and
hence is a landmark visible at a great distance. As soon as
a tribe of Indians come in sight of it, they offer their
adorations by loud shouts. The tree itself is lowq much
branched, and thorny. Just above the root it has a diameter
of about three feet. It stands by itself w’ithout any
neighbour, and was indeed the first tree we saw ; afterwards
we met with a few others of the same kind, but they were
far from common. Being winter the tree had no leaves,
but in their place numberless threads, by wdiich the various
offerings, such as cigars, bread, meat, pieces of cloth, &c..