Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1919-06-24
How Old Is the. Earth?
Literary Digest.

kNcIdIy Ol&SSt
Is our planet 1000 millions years old? Or
only ten million? That depends on how you
figure is out. Dr. William Harvey McNairn,
of McMaster University, who writes in The
Scientific American Supplement, tells us that
there are three principal ways OF approaching
this problem. The one that gives the smallest
answer is the Oldest and depends on an attempt
to find out how fast the sun is cooling.
Our star. the sun, is not eternal" says DR..
McNarn's article. Sooner or later its fierce
heat will all have been disspated into space, and
lit will become cold and dead. And the life of
our planet is bound up with that OF its parent
sun. 1t necessarily follows that the age of the
sun is a measure of the maximum life of the
earth. Is it, then, possible to measure in years
the length of time during which our sun could
continue to radiate heat at approximately the
same rate as we now experience, neither too hot
nor too cold for the existence of life? Lord
Kelvin's affirmative answer to this question in
1862 was so incsive and so surprising that the
scientific world was at once reused to vigorous
argument Now, taking this into consideration,
and putting the present temperature OF the sun
at 5000 degrees Fahrenheit, Kelvin concluded
that it has been only matter of about l8 100000
years that the sun has been at its present degree
of heat"
But even these millions do not give the geolo-
gists the time which they insist has been neces
sary to accumulate the vast deposits on which
we live and to develop the present great variety
of living forms, Since Lord Kevin's results
were first published their voices and those of
their successors have been constantly raised in
protest against the nadequacy of the time al
lowed them by the physicists. To quote again:
I'm order to attain some measurable repreSen-
tation of the extent of geological time, recourse
was had to two different geological processes:
the formation of stratified rock and the accumu-
aton of salt in the oceans, and both of these
have been studied with the greatest care and
with results of steadily increasing accuracy.
Nbe 1otin Of he Of
sedimentary rocks is based upon the fact that
the material of which they are composed was
carried down by the rivers and deposited under
the shallow water which surrounds the CONT
nents. If we could measure the total depth of
all such accumulations, and if we could gage
the average load of mud and sand and gravel
that goes down to the sea with each years quota
of river water, the problem that we are trying
to solve would resolve itself into one of simple
division. The latest and best figures available
put it at 1886, 900 feet, or about 81 miles.
1--WE have now to determine the rate at which
these sediments are accumulated This has been
set by some observers at three inches per CEN
fury, which would make the time requisite to
form the total 100000 years; by others it has
been placed at four no INCHES per century, which
five inches, with consequent reduction of time
to 100000 of years.
"The other method, most ingenious one, first
made use of by Professor Jolly, of Dublin Uni
versity, is based upon the theory that the salt
ness of the sea is due to the fact that since
they began to flow the rivers have been carrying
salt in solution down to the oceans, the bulk OF
the salt still remains and so the ever be-
comes sater. 1t is evident that if we knew the
amount of salt now in the ocean, and the rate
at which the rivers have been delivering it, the
length of the time occupied by the process is a
matter of very simple calculation. Unfortunate
ly however, the initial figures are most difficult
of attainment The best measurements at pres
ent available set the amount of sodium in the
seas at l4,l30 billion tons, and each year the
$500 cubic miles of water which the rivers con-
tribute have dissolved in them 175,000,000 tons.
After all necessary corrections have been made,
the, final result gives period somewhere be-
tween 100000 and l50,0o0,o0O years, with the
weight of evidence tending rather toward the
smaller figure" ,'.'t
Now we come to the newest, and perhaps
most interesting method-that based on radio
activity Says Dr. McNairn:
Among those elements which known to
undergo the mysterious change due to disinte-
grafton of the atom is uranium. By giving OFT
particles of heum at constant and definite
rate, uranium is believed to pass into
radium and lead If in any given uranium bear
ing mineral we determine the relative pro-
portions of uranium radium and helium, and
lead if it is present, knowing the rate at which
these changes take place, we should be able to
determine the age of the mineral itself.
This method, first suggested by Sir Earnest
Rutherford, in 1906. was subsequently made
good by Hon. R. J. Strut. His results were
somewhat startling in the unexpectedly great
periods of time which they indicated. For in
stance, he allotted the very respectable antiquity
of l4l 100000 years to some rocks which were
found about halfway down to the earliest fos-
siliferous deposits However, these first figures
were not uniform. OF recent years these have
been tabuated and indicate certain amount Of
consistency, particularly in their unanimity in
extending the reach of geological time to an
extent undreamed of by the biologists. Who,
for example, would have dared to suggest, from
geological evidence alone, that we have to do
with periods of from 800 to 1000 million years."
OF our three schools of investigators as to
the extent of geological time, one thus tells us
from 100000 to 100000 years; the second,
about 10O000,0O0, and the third anything up to
1,60O0OO0Oo. We must admit, says Dr. Nc
Marin, that we have not advanced very far The
mean of 10, 100 and 1000 is figure of little
value. But there is sense in which these fig
ures are approximately the same-that is, when
they are compared with inhnity.
Brussels, The Magnificent.
a Brussels, the Belgian capital, in which Presi-
dent Wilson and his party have been given such
an enthusiastic welcome, was known as one of
the most magnificent cities in Europe as far