The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1900-10-20
LENGTH OF EARTH'S LIFE
About TWENTK-SIX MILLIONS OF
YEARS,

Professor-some Other Estimates.
The latest utterance on the age of the
earth is that of Professor w. j. Sollas,
who occupies the chair of geology at
Oxford, and is president of the geologi-
cal section of the British association
for the advancement of science. This
address, at the annual meeting of that
organization a fortnight or so ago, was
devoted to reviewing the estimates of
others and calculating his own opinion
on this interesting subject.
1t should be promised, says the New
York Tribune, that inasmuch as mat
ter is believed to be indestructible, the
scientist has difficulty in understand
ing how it could have had beginning.
Hence the material composing the
earth is to be regarded as having eX-
listed forever, though its condition may
have undergone many changes. How
ever, even though it may once have
been a nebula. without form and
void" and though at one period in It's
history it was perhaps merged with the
far create mass comprising the other
planets and the sun, there came time
when it was detached from them all, ac-
quired globular shape, and was prob
ably Though not certainly so hot as
to be entirely molten 1t is customary,
therefore to specify some particular
stage in it's development as the starting
point for calculations of the earths
age. Lord Kelvin, for instance, dated
his estimate from the time when the
globe became cool enough to be habita-
BILE by the lowest known forms of life.
Kelvin placed the interval which has
elapsed since that era at between TWEEN
ty and forty million years, but he be-
lieyed shat it was nearer the former
figure than the latter This computa-
ton was based principally on the rate
at which various kinds of rock VIII ra-
date heat, and on the assumption that
the rate has remained uniform from
temperatures like two thousand and
twenty-five hundred down to that now
observed at the earth's surface, Pro-
fessor Solas remarks, however, that T
another factor in KelyinS estimate was |
the supposition that the temperature of I
the supposition increases one degree for I
every fifty-one feet Of Depth whereas I
other authorities make the rate less
rapid. The oxford geologfst believes /
that one degree for eighty or ninety |
feet would be nearer the correct aver
age. He specifies several instances |
where it is even slower than this. In /
the Lake Superior copper mines the |
rate is one degree for every 223,7 feet
of descent. modification such as is
here suggested would bring Kelvin's
figures up to about fifty millions.
Then there is Prof. George Darwins
fascinating calculation, based on the
belief that the moon was thrown off
from the earth in a tiday wave. At
that time the latter body was supposed
to be rotating on it's axis in a period of
from two to four hours. The suisse
quent retardation Of its speed through
the attraction of the moon would, ac-
cordinG to Professor Darwin's mathe-
matics, require something like ffty-six
or fifty-seven million years at least and
possibly more. Professor Sollas thinks
that this theory has strong claims to
acceptance, and he picks no flaws in it,
though eventually Offering different
estimate of his own
Jolly based another computation on
the supposed rate at which salt had
been carried into the ocean by rivers,
But Professor Sollas offers several rea-
sons for suspectng that Jolly did not
adopt sufficiently rapid rate He
would therefore cut down Joly's eighty
or ninety million a year nearly one
half. Indeed, Professor SolIas courte-
ously betrays considerable lack of
confidence in the ocean salt system of
computation.
The particular class Of evidence to
which the oxford geologist attaches the
largest importance is the depth of those
rock formations which are clearly of
sedimentary origin. Taking these at
their greatest thickness, wherever this
may occur, he finds an aggregate de-
post of about fifty miles, or two hum
dred and sixty-four thousand feet
Great difficulty is experienced in hit
ting upon an approximate average rate
of deposition. But Professor Sollas, af-
ter presenting elaborate reasons for so
doing, adopts one foot a century as the
most satisfactory Standard and with
this basis, he gets little over twenty
six million years as the time which has
elapsed since the formation of sedimen-
tary rocks began. The whole tendency
OF his argument is aVOWedly to har-
monte the estimates Of others as far
as possible, and it will be observed that
he comes much nearer to Lord Kelvin's
figures than to either Professor OAR
wins or Professor Joly's.
Those who have followed the discus
sion of this subject for more than a
quarter of a century will recall that
Huxley deemed period of even one
hundred million years hardly adequate
or the play of forces whose activity is
in the rocks. But while
speaking as a geologtst, Huxley also
advocated the theory held by progress
'ive biologists thirty or more years
lgo that the evolution of life from the
owest forms to the highest could not
laVe taken place in anything like the
limits allowed by Kelvin. There again
anne a demand for one hundred million
ears or more Without referring to
huxley by name, Professor Sollas
aises the question as to how far twen-
y-SiX million years will satisfy the BIZ
'ligtsts, and then replies, amply"
This particular argument hinges on
he susceptibility to change shown by
'arious forms of animal life, whose
OSSil rena ms have been discovered