New Iberia enterprise and independent observer. (New Iberia, La.) 1902-1944, 1916-04-01
w ASdiNGTON NEWS ITEMS.

the banana Canal viii not b,
swallowed UP by an earthquake
III the future and that the trou
b!esome Sides now being Ell
coLntered viii eventually be con
qlcied and the great waterway
made an unqualified success, Is
the opinion OF Donald +. Mac
Dona4u. tOrmeri V canal geO4OGl>t
and now mining SeU-OSIst tor the
tnteu States bureau III MineS.
Mr.. Macdonald. VINO spent sew
eral years on the lsthmus max
ing a careful study as 10 tragillty
o! tAe earth S crest, has Just mace
an Official report to the effect
that. While through seismic DIS
turbances the whole Is.Lmus is
RISING at the rate OF three fec;
every hundred years. this will nos
necessarily injure the canal. AS
FAR as he sees. it will merely mean
Il little additional expense in the
dredging Of the big waterway.
The cause Of this rising, he says,
is The sinking of the ocean bottom
outside the 1sthmian shore Vat
ers. Everytime there is little
movement of the ocean bottom,
the lSthmlS to DE in harmony.
joins in. He also suggests that if
The rising motion be rapid. then
there would be serious danger for
the canal, but. that from what has
happened in recent geologic time,
it may be concluded that the
canal is not in any appreciable
danger from the instability Of the
lsthmian land. The rising of the
isthmus. however. has been re-
sponsble for the many slides
th:t have been encountered. in
that the motion Of the ground has
dislocated and crushed the rocks,
leaving them weak and unstable.
"At any rate says Mr.. Mae
Donald. so far as the digging of
the Culebra Cut is concerned,
these faults have increased the
cost of the canal several million
dollars.
CAS- to the slides. Culebra Cut
is vast ditch that passes
through many varieties of rock in
the nine miles Of its length. Some
of these are weak and unstable,
and whefe the slopes of the cut
were steep and 100 to 900 feet
high the weaker rocks crushed |
down to flatter slopes. When
ever the slope got fiat enough,
the sliding stopped. At no time
did the engineering staff con
structing the canal believe that
the slides were a menace to the ul-
innate completion and successful
OF Grafton of the canal. in spite
of the fact that at times they
were somewhat troublesome.
They have made necessary the
excavation of about 30O0O.OOOI
cr'''c yards more than was n
cluded in the first estimates for
Culehra cut. but they have not
in the past and will not in the
future endanyer the ultimate
success of the canal"
Mr.. Macdonald calls attention
to the fact that one is apt to for
get that the greatest variation of
atmospheric pressure near sea
level may be more than four mil
hon tons per square mile and that
if the adjustment Of atmospheric
pressure. in very large cave
or mine lacs behind any quick in
crease in atmospheric pressure at
the surface. a considerable strain
may be added to the roof of such
an excavation. Discussing the
real cause of the slides. Mr.. Mae
Donald declares that in MANY
cases the immediate cause was
the oversteepness and height of
the slopes. the blasting and other
work attributable only to man.
He adds that the geologic condi-
tons were not sufficiently consid-
cred in the lrst plans for digging
Culebra cut.
As the strength of the famous
';atun dam has been brought into
question on a number of occa-
Mons. Mr.. Macdonald refers to it
n some length. 1T was found
hat the Gatun rocks are relative
V solid and compact and suitable
or foundations for heavy struc-