The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-12-05

''N'''AsS vi = Holth VI oolu Hll1.
While breaks occurred at various
places along the line OF the canal,
those In Gaillard Cut, or the cav
ton through the continental divide,
were the most serious, because of the
heterogeneous masses of material
which composed It and the depth Of
the cutting. which affected the terri
tory adjacent to the M for a m
siderable distance. and therefore
brought down large quantities OF ma
terial.
First Trouble in 1854.
The French company experienced
difficulties with "a slide at Cucaracha as
early as 1884, but all the indications
pointed 10 n surface movement only,
n this opinion was supported by
g~eolog1sts who examined into the mat
ter. With the possible exception of the
French member. who is said to AVE
been somewhat apprehensive on the
subject, the international board OF
engineers anticipated no difficulties
from landslides, as their report clearly
indicates. and as does also the testi-
mony OF those members OF that board
who appeared before the committees OF
Congress dealing with the canal. The
slides that were regarded as probable
were surface movements of the clay
covering the rocks, resulting from the
heavy rains, and these were provided
for by arranging the slopes in a series
of steps OF a general inclination OF 40
degrees. the angle of repose of ordinary
earth.
After the United States forces began
work, sliding at CuCaracha continued.
and in 1906 a gcolOgist was employed
who, after spending some months max
ing personal examination of the geo.
= logical formation of the country ira
, versed by the canal, made a report on
the subject. which was published In
full in the annual report of the 18TH
milan Canal Commission FOR 1907. In
this report he states:
THE relation of the lsthmian geol-
ogy to the varied problems OF cana!
construction is. in all cases, intimate.
one of the problems hat j. closely
connected with the geology is that of
! the excavation Of the cut in the cen
trail area. Actual work has advanced
4 so far in this region, however, that
geology can add little to the practical
information acquired in the course Of
the excavation that has already been
made. \ less evident, bat perhaps
closer, relationship exists between the
geology n tn. problems attendant
upon the construction ~ the locks aud
dam ms, while the necessity of ob'ain-
ing large quantities OF building mate
rial near the points whcr" locks ard
---. ,,.-,i,r Z. Sc. -, Ia. .tt = ~ rFn,l
calls for a special study
value of tho GroIoeist.
From this 1t would appear THAI the
excavation In the cut o be at
tended with few difficulties other than
those which are usually encountered
In work Of such character and mag
nitude. and that the services of a
g~eologtst in connection with the canal
would be OF value with respect to the
locks and the construction materials
required therefor, rather than the eN-
cavation through the continental Ill
vide. However. he discusses subSe-
uueutly. in the same report, IN" con
l!tions Of the II in n vicinity OF
our present difficulties, in n manner
still more explicit. ~ follows:
THE physical character nj the Gu
Zebra beds, consisting as they do of al
ternating layers Of sandstone and shalc,
Is peculiarly favorable to landslidcs,
StruCturaliy. however, the strata are so
nearly horizontal, or have such low
southerly dips north Of Gold I'LL, that
movements involving largo masses of
rock are improbable. while slopes Of
suitable angles Will do away with the
danger of minor slips,
Gold Iill Is bounded on the north
and south by faults, the mass OF the
hill having sunk with respect TO the
rocks on the other side Of tho faults,
During the process OF faulting the
strata We're twisted 20 the eastward,
and now have steep dips I'm that direc-
ton. This structure il also Compli-
Gated hy large masses OF intrusive ba-
salt Which were included in the Cuiebra
beds prior I o the faultlnE. The indura-
ton resulting from these ir'rusions
has been so extensive that all the
rocks In Gold Hin are now very hard
and firm, and with the s~edimentary
beds dipping into the hill the cordi-
lions are such that landslides are most
unlikely to occur.
/. Soft Bcds In Culcbra.