The Passage Took Some Hours,
As The River Here Consisted Of A Labyrinth Of Small Streams,
Separated By Low Wooded Islands.
I had a letter of introduction
to an old Catalonian Spaniard, who treated me with
the most uncommon hospitality.
The Bajada is the capital
of Entre Rios. In 1825 the town contained 6000 inhabitants,
and the province 30,000; yet, few as the inhabitants are, no
province has suffered more from bloody and desperate
revolutions. They boast here of representatives, ministers, a
standing army, and governors: so it is no wonder that they
have their revolutions. At some future day this must be
one of the richest countries of La Plata. The soil is varied
and productive; and its almost insular form gives it two
grand lines of communication by the rivers Parana and
Uruguay.
I was delayed here five days, and employed myself in examining
the geology of the surrounding country, which was
very interesting. We here see at the bottom of the cliffs,
beds containing sharks' teeth and sea-shells of extinct species,
passing above into an indurated marl, and from that
into the red clayey earth of the Pampas, with its calcareous
concretions and the bones of terrestrial quadrupeds. This
vertical section clearly tells us of a large bay of pure salt-
water, gradually encroached on, and at last converted into
the bed of a muddy estuary, into which floating carcasses
were swept. At Punta Gorda, in Banda Oriental, I found
an alternation of the Pampaean estuary deposit, with a
limestone containing some of the same extinct sea-shells; and
this shows either a change in the former currents, or more
probably an oscillation of level in the bottom of the ancient
estuary. Until lately, my reasons for considering the Pampaean
formation to be an estuary deposit were, its general
appearance, its position at the mouth of the existing great
river the Plata, and the presence of so many bones of
terrestrial quadrupeds: but now Professor Ehrenberg has had
the kindness to examine for me a little of the red earth,
taken from low down in the deposit, close to the skeletons
of the mastodon, and he finds in it many infusoria, partly
salt-water and partly fresh-water forms, with the latter
rather preponderating; and therefore, as he remarks, the
water must have been brackish. M. A. d'Orbigny found on
the banks of the Parana, at the height of a hundred feet,
great beds of an estuary shell, now living a hundred miles
lower down nearer the sea; and I found similar shells at a
less height on the banks of the Uruguay; this shows that
just before the Pampas was slowly elevated into dry land,
the water covering it was brackish. Below Buenos Ayres
there are upraised beds of sea-shells of existing species,
which also proves that the period of elevation of the Pampas
was within the recent period.
In the Pampaean deposit at the Bajada I found the osseous
armour of a gigantic armadillo-like animal, the inside
of which, when the earth was removed, was like a great
cauldron; I found also teeth of the Toxodon and Mastodon,
and one tooth of a Horse, in the same stained and decayed
state.
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