The Hawaiian gazette., 1877-01-10
When was the Earth Molten.

There are widely differing opinions among
physicists and biologists as to the length Of time
which has elapsed since the earth was in a mol
ten condition. The Darwinian hypothesis Of
development calls for very long period during
which life was developed on the earth. and geo.
logists who incline TO this view. make
much Of the faultiuess of the geological record
which has left long gaps Of time unchroaicled.
This class OF biologists have roughly estimated
the age of life on the earth at one hundred mil
lions Of years; bu. the Glasgow school of physi-
cists, headed by Sir William Thomson. have ad-
yanced arguments. based on physical experiments
in the cooling of rocks, to show that the earth
can not have been more than ten million years
in cooling 10 its present state, from the tenpera
ture OF two thousand degrees centrigrade. Sir
William Thomson has lately brought forward a
new argument for the short period based on the
demonstrated rigidiiy OF the earth and the dimi-
mutton of rate OF rotation. Ii is evident that
the spheroidal figure OF the earth was caused by
its rotation on its axis When in fluid condition.
At least so much OF the earth as is now fluid.
viz, the ocean. conforms itself TO the spheroida
figure which is dee to the centrifugal action Of
the earth's rotation. THIS centrifugal tendency
Of matter al the earth's equator keeps the ocean
level several miles higher at this equator. con-
sidered in relation TO the centre of the earth,
than q, the poles. 1t ia also evident that
diminution Of the earihs rate of rotation would
tend TO reduce the protuberance at the equator
and rise the water at the poles until finally, il
the earth were entirely without rotating move
ment, the fluid on its surface wonld conform to
the outline of o perfect sphere. Now SIR VIM.
homson demonstrated that the solid part of the
earth Is so rigid that its rotation velo-
city very much diminished the protuberance of
the land u the equator would remain nearly al
the height it now Is. Hence he argues that as
its present shane is nearly accounted for its
present rate Of rotation, and as the rate of rota-
ton is known to be slowly diminishing, it can
not have solidihed to its rigid condition at =
time go long ago that its rate of rotation was
much faster than at present. IL we trace back
the rate Of rotation much farther than 100000
years we come TO time when the earth's figure
must have been much more oblats Than it nov
is. The equatorial diameter may have been
more than lO miles greater than the polar dia-
meter. II sslidifcaiion took place 100 900 600
years ago, how eau we account for the fac, that
the figure Of lie earth is nearly that required By
its present rats Of rotation while we have good
evidence that the rate of rotation has been con-
stautly diminishing?
In reply to this, James CrolI, an advocate Of
/ the long period, has shown that Sir William
/ Thomson does not take into account the fac,
/ that there sre forces operating to change the
Z shape of eveo the rigid earth, as, for iustance
I the wearing iction Of air and water. Although
the surface q the earth remains unaltered from
ge-eratiou degeneration. stll it has been salts
lactorily proved that the air and water wear doEr
the land and carry it into the ocean at the nts
! of about Of ore foot in six Thousand years As
this wearing process does not take place beneath
! the surface q the ocean, but on the contrary
building up Is gong on there. it follows that the
ocean regllaes-if We take long periods Of timt
into the accountable average height Of the
land that is that if the ocean should subsid.
slower than st the rate Of one foot 10 six thou
sand years The hand would keep pace with this
subsistence BY the process of denudaiion
Hence, if We take such periods OF time as mil
lions of years into consideration, we shall enc
that the figure of the earth will conform yer,
nearly to the figure Of the faid portions of IL
surface. and this figure is determined BY the rat,
of rotation. The dimihution Of the rate of 70
iation is go SLOW that the equatorial protuberenc
of the solid earth left behind BY the sinking
ocean at the equator, would be sculptured o
abraded to the ocean level by the action Of al
and waller.
Mr.. Croll therefore argues that if the earth OF
becoming perfectly rigid were rotating at such 8
rate as to maze its figure as oblate as that o
Jupiter, the 'culpturing action Of the wind an'
rain has been sufficient cause for the remova
Of such an Immense equatorial pro,uberance
At no time in no possible changes Of figures. csl
the land differ much 10 Level from the fluid ocean
The figure Of The earth lie as plastic under tn
combined action Of denu6ation and the ocean q
il its whole substance were faid.-America
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