The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1867-02-20


Who is there that has not had bis won
der excited by the stories told of glaciers
In recent lecture in New York city,
Professor Agassiz entered into detailed
account Of their formation, peculiarities,
&c. We make some extracts which will
be found extremely interesting:
TAKE THIS TO START WITH.
Observations which made few years
ago in the State OF Maine satisfied me that
the glaciers in that section OF the country
must have been something like 5000 feet
in their thickness; and am satisfied now
that we have had snow-felds upon TINS
continent covering the land to the depth
Of 10000 or $4,000 feet. The whole OF
North America has been covered with Ice
down to latitude thirty-six degrees, may
be TO thirty.two degrees that is, to the
latitude of Charleston, S. G. | saw, when
in Columbia, S. c., unmistakable marks OF
glacial action. / have seen them on the
banks of the Ohio. / have seen them IN
the western States and could not resist
tbe evidence that to that latitude on TINS
continent the climate had been low enough
to sustain glaciers as they are now In Greeh-
land.
WONDERFUL TRIUMPH OF SCIENCE.
To satisfy his audience that he spoke un-
derstandngly, the Professor explained tne
marks left by the moving glaciers, ana salo
that when in the valley Of the Amazon, ne
lectured at Para [by the way, In SPANISH
and told his hearers that in Sierra would
he found certain morains made by the GA
ciers. He had never been in Sierra.
told them that traces of that morain should
he found there, and when several weeks
after | visited it, found in Sierra such
traces of glaciers as can fairly be compared
with those which are seen in the immedi-
ate vicinity of the Alps, or in our regions
where the ancient marks of glaciers are
most distinctly observed. lApplause.l
ANOTHER coNJECTURE-IsLANDs.
All the islands along the coast of Maine,
along the bay of Massachusetts,, and south
of the shore of Connecticut, Long Island
included. are covered with loose materials
of a glacial character which are of the
same kind as those resting on the conti-
nent. and of the same height, showing that
the sea must have washed that which IS
wanting for the level on the continent, and
the level on these islands could not have
been maintained the same by the onward
movement of glaciers if there had been
breaks there. This furnishes us the evil
dence that all these isolated parts of land
which stand out in the ocean were once
portions of the continent connected with
it only by the loose materials pushed for
ward by the glaciers.
The Nile, the Mississippi, the Ganges,
all great rivers, have deltas. The Amazon,
the longest and muddiest, has none, be-
cause the coast is composed solely of
loose materials once triturated by the
glacier and accumulated along the shore.
There is no delta because the ocean en-
croaches on this coast at such a rate that a
band of 300 miles has been removed from
in front of the valley of the Amazon. l
was induced to make this search-for it
was not an accidental discovery-after the
amount of coast lost by the entertainments
of the Atlantic upon the mouth of the
Amazon by facts which / have observed
in our own country [above mentioned as to
islands,.
All the bays of our great rivers empty
ing into the Atlantic were once filled with
loose materials by this immense sea of ice
advancing toward the ocean, and it was
when the ocean began to gain on the re-
treating glacier that these loose materials
were moved out, and the melting of the
ice made room for the accumulation Of
fresh water upon the surface, and then
freshests have taken place which have hol-
lowed every river stream, and the surface
of the land has been carved 20 its present
h,
rose, the masses of ice dwindled away
until they were circumscribed within the
Arctic region.
AN IMPORTANT POINT.
I attach great Importance, IN pnlio-
sophical point of view, to the study OF TINS
ice period, because if it can be demon
strated that such was once the condition OF
orr earth, it will follow that the doctrine of
the transmutation Of the species, and of
the descent of the animals that live now,
from those of past days, is cut at the root
by this winter, which put an end to all
living beings on the surface Of the globe.
[Applause.]
ICE AS TRANSPARENT TO HEAT AS GLASS is TO
LIGHT.
Suppose we have here large fire, and /
place between the fire and myself large
glass screen-a large pane ofglaSs-l shall
see through the pane of glass, and see the
fire and the blaze, but I shall not feel the
heat, because, although it is transparent to
the light, it is opaque to the heat-heat
does not readily pass through glass. Hence
it is that we make windows of glass, which
interferes with the change Of temperature
from within and without. Take instead of
such glass screen plate OF ice-an ice
screen-and place it between yeu and the
fire, and you will have the same phenome-
non as to viewing the light the blaze will
be seen, but the heat will pass through. A
pane Of ice is as transparent to heat as
pane of glass is transparent to light. SO
that, through sheet of ice on the surface
of lake, when the sun shines upon the
water, the stones on the bottom receive
heat and in that manner air bubbles are
made to rise constantly. Through large
mass of ice, rock which is at some depth
under the surface of the ice may be heated
the rock may be exposed and will appear.
WHY A GLACIER MOVES AT ALL.
1t moyes in consequence of the freezing
of water, resulting from flowing, and
which, while freezing, expands. You all
know that frozen water occupies more
space than liquid water. If you allow
water to freeze in bottle which is corked,
the bottle will burst, because ice occupies
more space than water. The amount of
water which penetrates the ice of gla-
cier, and penetrates through it, is not only
that which results from the melting of the
ice, but whenever, instead of showing, it
rains upon the glacier, the rain penetrates
into all the holes and assures in the ice,
sinking until it is arrested by the snow;