South Bend news-times. (South Bend, Ind.) 1913-1938, 1916-03-25

slides is the stratiGed Cucaracha
formation n is composed Of slip
perry minerals which are only weak
ly consolidated. The Cucaracha
beds are limited. along the line OF
the canal 10 the Culebra district
but they have a thickness in places
OF over 400 feet The soft slippery
nature or its materials are their
loose. unconsolidated condition
make f. unusually weak and unable
10 sustain any considerable lead
The strength of the Cucaracha
clays is greatly decreased by the.
presence Of water, and the heavy
tropical rains keep them nearly sat
urated the greater part Of the year;
for the broken and irregular surface
OF the slides and the open cracks
around their borders greedily drink
in the water that falls upon them.
In the Culebra district the aver
age rainfall since 1884 has been
S7.68 inches per annum. of which
about so inches falls in the rainy
season Of about eight months
Where nearly seven feet of water
fall upon the surface of the country
within eight months Of the year. it
is not surprising that there is diff
Guilty in controlling the underground
seepage. Indeed, during these
practically at the surface, except
possibly on the sleeper slopes; and
the movement of the underground
water is so slow that even in Il e
dry season the water table is not far
from the surface in the level coun-
try. There is no evidence that any
OF the slides have been started or in
creased by earthquakes.
I'm addition to the danger Of the
slides, there is no danger that the
canal may be blocked by the fall of
the hills OF Culebra district
The excavation of the canal, and
borings in it's bottom show that a
narrow belt between the two hills is
composed Of the soft Cucaraha beds;
, yet 20 the present time there has
| been no upheaval of the bottom of
/ this part of the canal. nor any other
| sign TO indicate that the hills have
settled. II is believed. therefore.
that the great masses OF gold and
contractors hills are self-supporting
and will remain so. There is no
| occasion to raze them.
| I'm addition to the immediate
| remedial measures suggested above,
there are certain observations and
protective measures which should
! be undertaken with view to the
] future. A few slides are now in
motion, but many more are quies-
cent. slide is not necessarily
| dead" because ii has not moved
notably for a few years. It's stabil-
/ ity may hang on a delicate balance
which may be disturbed by some
slowly developing weakness. There
is also a bare possibility that gold
and contractors hills are not so
\ firmly supported as they are believed
10 be. Repeated surveys Of proper
\ " placed signals for a number of
/ years to come should be made.
/ Two or three core bOrlngs
/ should be made on each side of the
/ canal. TO study the nature OF the
\ high hills. A mechanical testing of
\ the strength Of various rocks is
! suggested since the future OF the
slides is largely dependent upon the
/ strength Of the rocks. Greater ia
/ cility for the study Of earthquake
shocks in this region are also rec
commended.
"Culebra district is the chief area
OF danger. Slides may occur in
other parts Of the canal, but they
will be relatively small. and infre-
Quent; for the banks are not high.
and the unstable ground has al
ready slid down so that its surface
has approached the angle of re-
pose. Should slides occur. they are
not likely 10 menace the operation
OF the canal Slides. great enough
seriously to Cbstruct traffic in the
canal. could occur only in the Guile
bra district. which is but one mile
long.
In general. the committee be-
I lieves that no great extension Of
these slides is probable, because the
soft rock constituting a very large
part OF the slides is quite limited in
extent. except east of the east Guile
bra slide. and conditions elsewhere
are unfavorable for extensions
The committee OF investigators
consists Of:
william Fl. WEIGH. Charles r. Van
Hise president OF the University OF
Wisconsin. Gen. H. L. Abbott. corps
Of engineers United States army:
John G. Branner. geologist and for
mer president Of Stanford univer-
Sity. Whitman Cross. geologist in the
United States geological survey. r.
G. Carpenter. professor Of mechani-
cal engineering in Cornell univer-
sity: Arthur 2. Davis. chief OF the
Recla nation service. Washington:
JoI =. Freeman. construction en-
gineer. providence; T. ?. Havford
dean Of the College OF Engineering.
Northwestern; Harry FIELDING Reid.
professor OF engineering. Johns Hop
hIns university.