The Wilmington daily Republican. (Wilmington, Del.) 1890-1902, 1892-12-08
AGE OF THE EARTH.
A FASCINATING STUDY THAT IS Etu-
CHATTING A GREAT MYSTERY.

The Science of Geology Shows That the |
Age Of the World Varies Between 49, |
100000 and $50, 1000, 900 Years-How
These Computations Are Made.
At the recent meeting Of the British
association a discourse was delivered by
the president, Sir Archibald Gerkie, on
one Of the most interesting problems in
modern science-the age Of the world.
Over a century has elapsed since James
Hutton wrote his "Theory of the Earth"
which was the first attempt to formulate
a chronology of creation in accordance
with the discoveries of science; since
then knowledge has made vast strides,
and his followers have access to a mass
of information which he did not possess.
Playfair and Kelvin improved upon his
work, and now Gerkie and the school to
which he belongs have gone beyond
them.
Biologists have ascertained that the
rate at which erosion takes place can be
measured; by applying their scale to the
sedimentary rocks they have formed a
hypothesis as to the time which has
elapsed since erosion began. To put the
proposition in similar language, the sur
face of the globe is constantly wearing
away under the influence of water and
wind. The portions which are worn off
are carried down to the sea or into hol-
lows, where they are deposited and form
sedimentary rocks. If we can ascertain
how long it takes to form sedimentary
rock we can figure out when the progress
of wearing away and redepositing began.
/ Sir Archibald states that on reason
able computation the stratified rocks at
tain an average thickness of 100, 900 feet.
The material of which they consist was
all washed down from high planes, de-
posted and left to stratify. By the in
spection Of river banks it is found that
in places the surface of the land which
has been carried down as sediment in
rivers has been reduced at the rate of
foot in $50 years, while in other places,
where the land was more stubborn or
less flexible, it has taken $500 years to
lower the surface one foot. The deposit
must be equal to the denudation. Thus
we find that while some of the sedimen-
, tary rocks have grown a foot in $50
; years others have taken $500 years to
i rise that height Thus the period Of
!, time that was required to build up 100
600 feet of sedimentary rock has varied
| according to locality from $4,000 900
!, years to $50 ,0O0, 900 years. 1t follows
that the active work of creation lasted
for cycle intermediate between these
two figures. The cycle varied with end
less succession of periods of disturbance
i by volcanic force and glacial action
, and the frequent submersion of dry
land, alternating with the emerging Of
continents out of the seas. These may
/ have retarded the growth of sedimen-
tary rocks, but they cannot have accel-
: Grated it.
/ A study of fossils teaches the steady
uniformity with which the work of
creation proceeded. Since man began
to observe there has been no change in
the forms Of animal and vegetable life.
A few species have disappeared-not one
/ new species has been evolved. Not only
/ do we find the fauna and flora Of ancient
! Egypt ms depicted ON monuments which
y are probably 5000 or 10000 years old
identical with those which are found in
that country today, bnt shells which in
!, habited our seas before the ice age and
!, grew in an ocean whose bed overlay the
Rocky mountains are precisely the same
+ species that are found in the Bay of
:, Monterey and the waters Of the Chesa.
peake. 1t is evident that there has beer
no essential change in the conditions o.
life since these animals and these vegc
q tables We're first created, yet how vast
;, the shortest period which we can assigi
al to the gap that divides us from that re-
. mote epoch!
Little by little the gcologist is lifting
10 the veil which covers the prehistori,
record Of our planet. The era whicl
preceded the age of civilized man, witt
u its vast rivers carrying down diluvia
- floods to the ocean, and the hurstiu,
! forth Of mountain ranges from contrac
ii tons If the earths crust has been painte,
to the life. But no one has exercised hi
pencil on that preceding age, when til
forests made way for clumps of stunte
u birch and willow, incessant snowfall
= covered the plains, glaciers crept dow
~ lIbul INT loItil, luu SItuHdllS was
4 sheet of ice half mile thick drove man
AZ kind, with the mammoth and the rein
deer, TO those fortunate regions which
like California, escaped the agony of tn
. last ice age.
OF Nor have we any distinct perceptio
of that subsequent age when the ie
melted or rtcelcd to the pole, or dens
n, tropical jungle grew up in the morasst
Nv Nv it had left, swamps steaIuing with trol
hoI ical heat swarmed with uncouth h,
al. trachian and reptile life, trees of MOI
strous growth shed their shade ov,
,t shiny pools and black ooze, and in Il
r distance long mountain ranges who
nJ fontanel had not yet closed, poured
'e. never ceasing food of lava down the
sides. This is IL page Of history whit
is yet to he written, but the materia
ps are accommodating, and the historian W
his not be long wanting. Francis
Gail