Evening star., 1940-07-16
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henri,


And Study
By Thomas r. Henri.
The $4,000, 900 900 neteors that shower
the earth every "A hours, wreckage of
some exploded planet and of disinte-
grated comets, are exactly as old as the
earth itself.
These celestial immigrants carry
properly attested birth certificates, ac-
cording to cumulative evidence reported
to the Geological Time Committee of
the National Research Council by DR..
Robley D. Evans of Harvard University.
These nativity records consist of two
age indicators-uranium and potassium.
Each occurs in two forms, differing
slightly in the weights Of their atoms.
All uranium, probably creations heav-
lest element. is radioactive, constantly
shooting out minute particles of its own
substance and energy. and changing into
another element. The heaviest form Of
the element breaks down into radium,
The lighter turns into protactinium, q
similar but chemically distinguished sub
stance. One atom of the lighter SUBJ
stance breaks up for every Is of the lat
ter, in the same time interval.
Now, DR.. Evans explains in his report,
the relative abundance of the two
forms in nature is such that the lighter
uranium tends to become less and less
in proportion to the heavier as time goes
on. 1t has relatively shorter life. BY
the same token the protactinium be-
comes, In relation to the abundance Of
its source, more abundant than radium.
Consequently If two bodies started life at
the same time the proportions of light
uranium to heavy uranium and of pro-
tactinium to radium would be precisely
the same. If one was older than the
other there would be less light uranium
and more protactinium.
When meteorites are analyzed, Prof
Evans said, they are found to check
exactly with rocks from the surface OF
the earth and all terrestrial uranium
bearing rocks possess the elements in
the same proportions.
The abundant element potassium also
occurs in lighter and heavier form.
Only the latter Is radioactive, shooting
out particles and changing into ordinary
potassium. Tests have indicated that
half the amount Of heavy potassium in
any specimen will disappear by this pro-
cess in approximately q billion years.
The ratio between the two isotopes of
the element is the same everywhere on
earth. that Is about one atom Of the
heavier form to 5000 Of the latter. Any
change in this proportion would indicate
a different age.
The measurements are very difncult
and must be carefully checked, DR..
Evans reports, but the proportions ap-
pear to be identical for meteorites and
chunks Of the earth itself This acts rs
a certincation Of the uranium birth
certificate.
1t turns out that both earth and the
meteors are about two billion years old.
This may be about the age Of the uni
verse itself, Prof. Evans says. An inde-
pendent study conducted at the Mount
Wilson Observatory of the Carnegie In
stitution OF Washington shows that the
relative amounts OF two forms of the
element lithium on the earth and in the
fiery atmosphere of the sun are ap-
proximately identical. There is a slight
difference between the wave lengths of
light emitted by the two FORMS and this
can be determined with the spectroscope.
The evidence strongly suggests. he
says, that all elements, uranium in
cluded, start their astronomical life
with the same ratio of abundance be-
tween their different forms. Hence their
disintegrations can be used safely as
age integrators.
Another Ice Age may be on the way,
according to a new line of evidence
being studied by DR.. Wilmot H. Bradley
Of the United States Geological Survey.
DR.. Bradley finds, he says, that the
mud being deposited on the ocean bot
toms today is much more like that which
was deposited during the comparatively
brief intervals between advances OF the
glaciers over North America than like
the deposits Of eras in which there were
no glaciers.
Mud on the ocean bottom consists Of
silt brought down by rivers and Of dirt
from melting icebergs. BY studying the
difference in the nature of the mud at
various layers scientists are able to tell
what kind Of climate existed at the time
that any layer was deposited. Study of
these layers also gives Information about
the activity Of volcanoes. Volcanoes on
land many miles away sent of fine ash
which settled on the ocean and eventually
formed layers on the bottom.
Activity of large submarine volcanoes
whose existence had not hitherto been
suspected is also revealed by these
studies. The layers are studied by taking
cores out of the ocean bottom at various
points, by means of an ingenious boring
device that can secure samples from as
much as three miles below the surface.
The Federal District
~-.,. = o..u M. \ .ritvsp