206 
REPORT ON THE PANAMA CANAL 
Two or three core borings should be made on each side of the Canal 
with a drill which would give large cores. At least one horizontal and 
one inclined hole should be bored on each side, their precise location to 
be fixed by a geologist. 
Underground Water and Related Data. — As underground water is of 
paramount importance in promoting slides, it should be carefully studied 
in the Canal Zone. A satisfactory investigation of this problem would 
require the following determination and studies: 
1. Profiles of water table for different locaHties of the Culebra District: 
(a) In the wet and dry seasons; 
(b) In areas in which remedial measures have been applied and 
similar areas where they have not. 
2. Percentage of porosity of the several formations of the Culebra 
District: 
(a) Absolute; 
(b) With regard to size of grain. 
3. The effect of tropical vegetation with the accompanying humus, 
its removal and its restoration, on: 
(a) The amoimt of water which sinks underground in sliding 
and in undisturbed areas; 
(b) Chemical action, such as oxidation, hydration, carbonation, 
etc.; 
(c) The composition of the water; 
(d) Changes in underground temperatures. 
4. The nature of the changes which result in the disintegration and 
decomposition of the various rocks of the Culebra District 
when exposed to weathering agencies: 
(a) With regard to volume; 
(b) With regard to chemical changes, i.e., oxidation, hydration, 
carbonation, action of acids, etc. 
5. The chemical changes which cause the so-called hot areas de- 
scribed by Colonel Gaillard and Mr. MacDonald: 
(a) Direct, in production of acids, etc.; 
(b) Indirect, i.e., the effect of produced acids upon the materials, 
including water and rock. 
6. Observations to determine whether similar changes to those in the 
hot areas take place elsewhere to a less extent over large areas, 
and whether such changes affect the slides. 
Mechanical Testing of the Rocks. — Sliding is largely dependent upon the 
strength of the rocks; which in turn is affected by the water content. 
The strength of the massive igneous rocks is well known to be great, 
