Nashville union and American. [volume] (Nashville, Tenn.) 1868-1875, 1874-06-21
THE GREAT ICE AGE.

antiquity of man. 1t is fascinating
volume, writer by a man who is mas
ter of his subject. The quantity OF
ice that exists in any age or country
and for any known length OF tme'
gives information in regard to its CHI
mate, and the adaptations and posslbl-
ties of the growth of plants and AMI
mails in the region and ageunder exam
nation. Life in all its forms, from
man down to seedless and fowerless or
ganisms, obeys the law of climate.
Greenland which has an area OF
10000 square miles, presents the do
minion of ice in perfection over waste
tracts uninhabited by any living thing
whatever. Crystalline granite is not
more hfeless and barren than snow and
ice-covered, frozen plants. During
'the great ice age" of Iceland, our
author. and others on her MaJestys
Geological Survey, give satisfactory
proof that an ocean of slowly moving
glaciers covered the country to the
depth of some $500 feet.
Prof. Dana, of New Haven, after
long and careful study of the facts
bearing on the question, estimates the
depth Of ice in Connecticut at from
5000 to 5000 feet in the glacial
epoch.
If cosmical, or astronomical changes
in the earth's orbit, the precision OF
the euuinoxes, and the variation of its
poles, are the causes of great changes
of temperature in both hemispheres, as
is now generally believed, oscillating
by vibrations Of the celestial pendulum,
the shortest of which is 81 900 years,
and longest unknown, we mayyet learn
why so many varieties, species and
genera of plants and animals exist,and
why so many more have persisted by
an memorable law of climate, and OF
essential conditions. Astronomical
| truth and light are comforting incalcu-
liable benefits in advancing our know
| ledge of climatology and geology.
Let the equal length of day and
night ON the Goth of March or 22d of
September come by the force of plane
tary attractions some twenty minutes
earlier every year, las is the case, and IN
time the equinox of spring will come IN
autumn. and the summer following will
be in the winter. Ten thousand fve
hundred years will bring about this
curious result by the procession OF the
equinoxes. But, the elpticIty OF the
earth's orbit, and consequently its ex-
centricity vary considerably by the
varying attractions of moving celestial
bodies with immense orbits. In about
$4,000 years from this time the eliphoi-
ty of the earth's orbit will reach one OF
its minimum points.
We have neither time nor space to
follow Prof. Geikie in even a brief as
Economical statement; but. az Gallleo
said of the globe, sit moves" 30 we re-
mark, in moving for unknown geolog-
icaI ages, it everywhere slowly changes
its climatal conditions. There was
time. doubtless, when there was no
gulf stream to warm the ice water OF
the Northern Atlantic and soften and
moisten the atmosphere OF Western
Europe. Let us suppose the annual
fall of snow compressed into ice in
New England and Scotland YES twelve
inches in excess of what melted; a cold
period of 5000 years would give exist.
ence to an ocean of ice of that depth
in feet over all land.
Rowland ice moves, and in its pro-
gress often grinds hard rocks into the
finest porcelain clay, brick clay, fine
and coarse sand, and scratcbe and peh'
bles, stones and rocks, and sometimes
scoops out of solid strata deep and
immense basins, ike those of Lakes
Superior, Michigan, Huron, Erie and
Ontario. is a process which we shall try
TO make plain to unscientifc readers
In the frat place it should be stated
that glaciers do move on slightly-in,
clined planes, as demonstrated by
Agassiz and others. If the mass of ice
remained a solid all the time 1t could
not move on the same plane, a:
is easily proved by experiment
The sun, shining on a glacier IN the
Alps or Rocky Mountains, does not ap
pear TO melt the ice nor to warm it, yet
sensible heat is observed, and hquities
a molecule of frozen water, which,
moving freely, goes down stream slight
" when the solar heat in the water
leaves it, and the water congeals again
and becomes the ice it was before. The
solar heat which liquifes another mole
cule of ice below is neither diminished
increased, nor changed in quantity OF
quality by passing from one particle Of
ice. to another. The second melted
molecule moves like the first, or al
water on slightly inclined plane
In time, this ndestructible force
called heat will pass through
an ocean of ice moving each
molecule through which it passes, with
out e5er having but one in hquiC
state at time. Coming at last dow
to the earth, this may be a little to-
warm to receive any accession of hea
from this source; and if so, the las
molecule of water at the bottom OF tn
ice, flows down as part of rill from
the glacier. Its volume and weight ar
diminished by so much as solar hea
takes away ice in the form of water
How warm sunshine passes so easllI