Evening star., 1938-01-22

The earth is stark naked under the
greater part Of the Pacific Ocean.
This conclusion. deduced from the
speed of earthquake waves in that area,
is presented in a report on oceanogra-
ply just issued by the National Academy
Of Sciences by DR.. B. Gutenberg of the
California Institute Of Technology.
Biologists are generally agreed that
the planet is surrounded by crust OF
relatively light rock averaging about 40
miles in thickness. This crust Is COM
posed of several layers, corresponding
to overcoat, suit and underwear. The
first layer is relatively loose rock and
earth through which earthquake waves
go quite slowly, the second Of granite,
with one or more layers of more COM
pressed granite beneath it. This all
overlays layer of dense basalt which
might be considered the planets skin.
The relative depths of the various layers
can be estimated by the speed and ma
ture of seismic waves passing through
them.
Now it is a strange fact, DR.. Guten-
berg says. that under greater part OF
the Pacific basin and part OF the Arctic
basin there is no evidence Of any crust
at all. He says:
If we summarize our results we find
that the region in the limits of the Pa
ciflc Ocean has one kind OF structure
and that all other parts OF the world,
except possibly part OF the Arctic, an
other. In the latter parts OF the earth
there is continental layer which con-
sists of several shells, in thickness be-
tween 40 and SO kilometers, under the
continents but which decreases towards
the Atlantic and probably towards the
Indian Oceans where the thickness Is OF
the order of 20 kilometers.
There is no indication that the con-
tinents have broken during geologic
time and drifted apart; however, our
findings would be in agreement with
the assumption that in early geological
times the thickness of the continental
crust was different in many localities
from what it is today and that plastic
flow in the continental crust may have
changed the distribution of earth and
sea In the area including all the conti-
nents, the Atlantic and the Indian
Oceans.
1.-THE basin of the Pacific proper is q
unique element of the earth's crust.
The conclusion seems probable that the
Pacific never had crust, or that it has
been removed by a cosrnic event."
The concluding statement Is in line
with the hypothesis that at some time
in the distant past the earth and moon
were one body and that some cataclysm
of unknown nature tore the matter COM
posing the present satellite out Of the
region now covered by the Pacific.
The earth's crust Is thickest, DR.. Gut
enberg concludes, in the region of the
Alps Mountains. It is very thin through
the Southwestern United States, most
of Western Europe and Northeastern
Japan, but is average thickness over
most of Western North America and
nearly all of South America. Even
parts OF the present Pacific basin, DR..
Gutenberg points out, have thin crusts
indicating that they are primarily con-
tinental, rather than ocean bottom,
areas. Such is the so-called Polynesian
region around the Caroline and Bonin
Islands and large region In the South
ern Pacific west of South America.
The report forms part of . compre-
hensive volume summarizing, mostly In
charts, the present status Of knowledge
regarding the earth's oceans, the depths
and salinity Of the water. the circula-
tion Of ocean currents, and the topog-
raphy Of the sea bottoms. It was pre-.
pared for committee of scientists ap-
pointed to make the study in 1927. The
data was assembled BY DR.. 7. Wayland
Vaughan, noted authority on oceanoos