Evening star., 1949-12-09
SiIurion Era Shifting
Of Eurth's Crust Noted
South Africa Rocks May Have Been
In Maine 800 Million Years Aao
By Thomas r. Henry


By Thomas r. Henry
Sudden and enormous shifts in the earth's
crust, with what Is now Northern Maine in
South Africa and vice versa, during the
Silurian geological era approximately 300.-
900 900 years ago, may be postulated from an
extraordinary phenomenon discovered by
geophysicists of the Carnegie Institution Of
Washington.
annual report today, promises to be among
the most revolutionary ever made in geology.
They are likely to force radical revisions
In all theories of earth history.
The mud and sand washed from the
continents into offshore waters settle in
layers at the bottom where, in the course
Of ages, they harden into sedimentary rocks.
This sediment contains tiny particles Of
lodestone, form of iron oxide known as
magnetic. These particles are infinitesi-
mally minute, the larger ones being about q
250,000th of an inch in diameter. Each is a
tiny compass needle. While 1t has free
earth's' magnetic field. It's northern pole
points to the north magnetic pole. Also
it dips downward. The higher the latitude,
the greater the dip. Over the magnetic
pole itself 1t would point straight down to-
ward the earth's center.
When the sediment Is hardened into rock
these magnetites are frozen in their posi-
tions. Thus they become magnetic fossils" +"
theoretically, they always will point in the
direction Of the magnetic pole at the moment
when they were deposited.
The reverse Is true in the Southern Hemi-
sphere. The south pole Of the needle points
to the south magnetic pole and dips down.
ward. the degree Of the dip depending on
latitude. Carnegie geophysicists have been
carrying out study Of this fossil magnet
ism for some years. working mostly with
rocks from $4,000, 900 to 100, 900, 900 years
old. They have found little variation In the
earths magnetic field, or the direction Of
north and south.
Lineup About the Same.
However, all this changed when mag
netites in rocks of the Appalachian range
near Hancock Md, were examined The
north-south lineup was about the same,
but the dip downward was on the southern
end Of the particle.
Since then eight other Silurian forma-
tions from Birmingham, Ala, to Eastport,
Maine. have been examined, and the same
extraordinary reversal was found.
The most obvious deduction is that these
rocks at the time they were formed were
about the same distance northward from
the South Pole as they now are southwark
from the North Pole. In other words the
present rocks Of South Africa may have
been in New England. while rocks Of the
present Appalachians were laid down in
South Africa.
Even more extraordinary Is the fact that
few feet higher in the same rock beds
the lineup Of the magnetites becomes
almost precisely as it is today. The dif-
ference In depth represents the sedimenta-
ton OF only few thousand years. Then,
few feet still higher, the fossil magnetism
again is reversed.
There Is no gradual transition between
one phase and the other. The division
lines are sharp, indicating that whatever
happened took place in aafew years, at the
most. Even In the face of such evidence,
the Carnegie geophysicists are loath to
accept picture OF a period in the earth's
history when the now solid crust of the
planet was so turbulent that parts Of con-
tinents drifted many thousands of miles In
q few years.
Breaking up and drifting Of continents
is an old hypothesis, but it never before
has been conceived on such a vast scale in
such short spaces Of time.
This does not mean change in the
location Of the poles themselves. The North
Pole presumably always has been under the
North Star and the South Pole under the
Southern Cross They change slightly in
position with the wobbling of the earth on
its axis. but only fractions of inches year
and miles, at best, in milleniums It means,
for example. that the land under the North
Star was violently transported somewhere
else.
Implications Held Fantastic.
The crust Of the earth is conceived of as
light shell floating on molten interior.
Under the old hypothesis Of continental
drift. fragments of this shell. the continents,
could be pictured, as one Carnegie geophys-
icist says, like shingles floating on a quiet
duck pond. The present evidence indicates
shingles on duck pond in hurricane.
How long such an unquiet time, If It
existed. may have continued cannot be con-
jectured. Fossil evidence, the geophysicists
have been assured makes it certain that
there have been no major shifts Of the
earth's crust for the last 100000, 900 years.
A period Of almost zoe, ,000, 900 years from
the end Of the Silurian remains terra
incognita in whose rocks no fossil magnets
have been found.
The implications Of the finds are so fan
tastic that the geophysicists are very hes
liant about accepting them. There are pos
sible alternatives which, In turn, raise diff
f1cult problems. One Of these concerns the
movements Of the earth's foci Of magne-
tism. There are eight known spots on earth
where the magnetic needle goes haywire.
This is supposed to be due to whirlpools
caused by the gravitational attraction Of
the moon In the earth's molten interior,
which in turn produce electric currents.
It has been determined lately that these
foci are moving slowly westward. They
may have moved very rapidly in the distant
past. In such case the reversed poles
shown by the fossil magnets might be due
to the existence Of such foci under the spots
where they are found. Calculations. how
ever. show that If this hypothesis holds
true the molten interior must have been
far closer to the surface than is the case
today.
Very much more evidence must be gath
cred. the Carnegie geophysicists say. before
there can be any explanation OF the strange
phenomenon they have encountered which
seems entirely in accord with any orthodox
doctrines Of cruStal movements