The Bridgeport evening farmer. [volume] (Bridgeport, Conn.) 1866-1917, 1916-03-17

felt in the canal zone and a, careful
examination of the instrumental rec
ords kept near the Pacific end of the
canal since the end of 1908 dispel
fear of serious damage to the canal
or it's accessories by earthquakes.
There is no evidence that any of the
Slides have been started or increased
by earthquakes.
I'm addition to the danger of the
slides, is there danger that the canal
may be blocked by the fall of the
hills of Culebra district? These
hills are composed of intrusive bodies
of basalt, or of masses of hard Obs
Pc tuf commonly associated with ba-
salt in this district. So far as can
be judged from present exposures.
they do not rest on the soft Cucara-
cha formation, but extend far into the
earth, and are disappearing. Rock
may slough off from them, but there
is no evidence that they will col
lapse
The excavation of the canal, and
iborings in it's bottom show that a
narrow belt between the two hills is
composed of the soft Cucaracha beds;
yet to the present time there has been
no uph eaval of the bottom of this part
of the canal, nor any other sign to
indicate that the hills have settled. Tt
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
The committee believes that every
available and practicable device
'sh ou1d be used to turn tt = water fall
ing rain from ground that is slid
ing and prevent its entering adjacent
ground and it suggests the following
measures:
i. Covering Slopes With vegeta-
tion.-Whether vegetation increases
or decreases the amount of rainfall
entering the ground is still a moot
question. The committee believes,
however. that threatening ground b0r-
dering the slides, Quiescent slides, and,
so far practicable, active slides
themselves, should be sufficiently COW
cred with vegetation to prevent, sur
face wash.
2. Closing PeripheraI Cracks
Before extensive movements of the
ground occur, warning is frequently
given by the appearance of cracks pc
ripheral to the coming slide. In some
instances cracks exist for a long time
before the important movements take
place. AS soon as they are formed
they should be filed up, in order
that they may not intercept surface
water and lead it into the slide.
3. Drainage of Undisturbed and
Threatened Areas.-Undisturbe and
threatened areas near the slides
should be thoroughly drained both
by surface and by tile drainage to
keep as much water out of them as
possible for they may become un-
stable and they may supply water to
the slides. Experiments with tile
drainage on a small scale would soon
show wheth er it%is effective enough
to justify it's extension. The sur
faces of the ground east of the East
Culebra slide and in places west of
the West Cu1ebra slide slope away
from the adjoining slides, and the
water can be readily removed. But
at considerable area above the Cuca-
racha slide drains naturally into it;
some of the drainage can be diverted
to the east, but the rest should, so
far as possible, be collected by sur
face and tile drains, and be carried
to the canal through large concrete !
lined drain.
4. Drainage of the Great Slides
A complete system of open drains
should be established on the great
slides and the water carried away
as directly as possible. The main |
drains should be made in1pervious on
the Cucarachas and, so far as prac-
ticable on the two Culebra slides.
5. Drainage by Tunnels.
by means of tunnels might be adapt
be tried with caution, and extended |
only in cases which promise results |
comm ensurate with the cost. The |
tunnels should be built underneath |
the sliding ground in the undisturbed
material and strongly timbered so as
to avoid risk Of collapse, which would |