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. This latter tooth greatly interested me,
and I took scrupulous care in ascertaining that it had been
embedded contemporaneously with the other remains; for I was not
then aware that amongst the fossils from Bahia Blanca there was a
horse's tooth hidden in the matrix: nor was it then known with
certainty that the remains of horses are common in North America.
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