Gold Hill daily news. [volume] (Gold Hill, N.T. [Nev.]) 1863-1882, 1866-07-16
AoAssrz IN BRAZIL.

The discovery by Agassiz OF clear
traces of a glacial period under the tropics
has been. to some extent. already made
known in published letters from his
friends and himself. He seems to think
i, will excite almost as much opposition
as his theory of glaciers over northern
Europe did thirty years ago. But what
Humboldt did half a century ago in open.
ing up to the world the Valley Of the
Amazon, has been carried on by Agassiz,
with a wonderful enlargement of knowl-
edge and resources. He treads in the
footsteps of that noble student. carrying
out his researches to an extent that even
Humboldt never dreamed Of.
From Rio de J~aneiro, through the
whole Valley of the Amazon, he found
the glacial drift, a sort Of reddish-as in
some other places Of yellowish-clay (; a
homogeneous unssra,i6ed paste, and con-
tanning loose materials Of all sorts and
sizes covering the country. 1t is Of very
uneven thickness, sometimes wasted en-
tirely away, leaving the bare rock scratch
ed by the great ice-plow. The fertility Of
the land is one Of the best guides to the
presence Of this drift. Wherever it lies
thickess there are the most Aourishing
coffee plantations. This fertility Of soil
arises from the great variety Of chemical
elements contained in the drift, and the
kneading process it has undergone by the
glacial action grinding it up SO finely.
We all know that water expands in
freezing, and where for ages immense
bodies Of fresh snow fall on masses Of ice,
and thaw in the sun and freeze up again
in winter and in the shade, this expansion
Of freezing produces a constant motion Of
the whole body, very slowly, from a few
inches to a few feet in the year, pressing
in the north towards the south, grinding
up the soil with an immense pressure, re-
moving huge boulders and growing the
rocks with deep burrows. A sheet Of
snow ten thousand feet thick, extending
all over the northern and southern por-
tons Of the globe, u necessarily lead
to a northern and southern cap Of ice
moving toward the Equator. Professor
Agassiz says: ~ have in Maine followed,
compass in hand, the same set Of burrows,
running from north to south, in one un-
varying line, over q surface Of one hun
bred and thirty miles"
This sort of ice movement is now
proved to have extended, in its turn, to
the regions lying under the Equator, the
whole Valley of the Amazon. Humboldt
had referred the Amazonian deposits Of
u~nstrati6ed red clay to the Devonian, and
Martius to the Triassic period and all
travellers had considered it at least as old
as the Teruaries. But, says Professor
Agassiz, 81 found in these very beds a
considerable amount Of well-preserved
leaves, the character Of which proves
their recent origin. These leaves do not
even indicate as ancient a period as the
Tertiaries, but resemble so closely the
vegetation Of to-day, that have no doubt
when examined by competent authority,
they will be identified with living plants.
The presence Of such ian extensive clay
formation, stretching over a surface of
more than three thousand miles in length
and about seven hundred in breadth, is
not easily explained" But since those
leaves grew and settled quietly in the
laminased mud at the bottom Of quiet
waters, the whole valley must have been
subjected to a polar climate for ages, sunk
down so that huge icebergs or glaciers
must have grooved the rocks and kneaded
the clay all ove its surface.
When we consider that it was not so
much the changes in the surface Of the
earth. but rather the undescribed flashes
that now populate the waters of the ANA
ION, that Agassiz went to Brazil to ex-
anime, we may well feel srati6ed in con-
templating the important geological facts
that a citizen Of our own country has re-
vealed to the world IN q single year Of
travel in Brazil. He has now returned
to Rio, and presented the Emperor with
magnificent collections in natural history,
and will bring home with him to the
United States. other equally valuable re-
suits of his researches in that interesting
country.