Nor Has Patagonia Been Affected Only By Upward
Movements:
The extinct tertiary shells from Port St. Julian
and Santa Cruz cannot have lived, according to Professor E.
Forbes, in a greater depth of water than from 40 to 250 feet;
but they are now covered with sea-deposited strata from 800
to 1000 feet in thickness:
Hence the bed of the sea, on which
these shells once lived, must have sunk downwards several
hundred feet, to allow of the accumulation of the superincumbent
strata. What a history of geological changes does the
simply-constructed coast of Patagonia reveal!
At Port St. Julian, [12] in some red mud capping the gravel
on the 90-feet plain, I found half the skeleton of the
Macrauchenia Patachonica, a remarkable quadruped, full as large
as a camel. It belongs to the same division of the Pachydermata
with the rhinoceros, tapir, and palaeotherium; but
in the structure of the bones of its long neck it shows a clear
relation to the camel, or rather to the guanaco and llama.
From recent sea-shells being found on two of the higher
step-formed plains, which must have been modelled and
upraised before the mud was deposited in which the Macrauchenia
was entombed, it is certain that this curious quadruped
lived long after the sea was inhabited by its present
shells. I was at first much surprised how a large quadruped
could so lately have subsisted, in lat. 49 degs. 15', on these
wretched gravel plains, with their stunted vegetation; but
the relationship of the Macrauchenia to the Guanaco, now
an inhabitant of the most sterile parts, partly explains this
difficulty.
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