I Stayed Here And At Some Neighbouring
Mines During The Two Succeeding Days.
The geology
of the surrounding country is very curious.
The Uspallata
range is separated from the main Cordillera by a long narrow
plain or basin, like those so often mentioned in Chile,
but higher, being six thousand feet above the sea. This
range has nearly the same geographical position with respect
to the Cordillera, which the gigantic Portillo line has, but it
is of a totally different origin: it consists of various kinds
of submarine lava, alternating with volcanic sandstones and
other remarkable sedimentary deposits; the whole having a
very close resemblance to some of the tertiary beds on the
shores of the Pacific. From this resemblance I expected to
find silicified wood, which is generally characteristic of those
formations. I was gratified in a very extraordinary manner.
In the central part of the range, at an elevation of about
seven thousand feet, I observed on a bare slope some snow-white
projecting columns. These were petrified trees, eleven
being silicified, and from thirty to forty converted into
coarsely-crystallized white calcareous spar. They were abruptly
broken off, the upright stumps projecting a few feet
above the ground. The trunks measured from three to five
feet each in circumference. They stood a little way apart
from each other, but the whole formed one group. Mr. Robert
Brown has been kind enough to examine the wood: he
says it belongs to the fir tribe, partaking of the character
of the Araucarian family, but with some curious points of
affinity with the yew.
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