REPORT ON THE PANAMA CANAL 197 
Mr. Comber's figures for excavation accomplished to December 30, 
1915, are: 
cu. yds. 
West Culebra Slide 10,931,862 
East Culebra Slide 14,687,563 
Cucaracha Slide 9,901,602 
Total 35,521,027 
In contrast with this amount, the total excavations for the other 
slides to the same date have been 4,852,648 cubic yards. 
If the amounts of material still to be removed are compared, the 
dominance of the three great slides is maintained. It is estimated 
that, on December 30, 1915, there remained to be excavated: 
cu. yds. 
West Culebra Slide 3,500,000 
East Culebra Slide 5,600,000 
Cucaracha Slide 500,000 
Total V 9,600,000 
The total amount still to be removed from all other slides is esti- 
mated at the insignificant amount of 330,000 cubic yards. It thus ap- 
pears that the amount of material already excavated and still to be 
removed from the three great slides is estimated at 45,121,027 cubic 
yards; whereas, the corresponding amount for all the other slides is 
5,182,648 cubic yards, or about one-ninth as much. 
The foregoing facts are conclusive as to the dominant importance of 
East Culebra, West Culebra and Cucaracha SHdes. 
Since the three great slides are all in the Culebra District, this is the 
chief area of danger. This is the natural consequence of the fact that 
by far the deepest part of the Canal cut is in this District; and that the 
weakest of the geological formations, the Cucaracha, is strongly developed 
here. 
Slides may occur in other parts of the Canal, but they will be rela- 
tively small, and infrequent; for the banks are not high, and the un- 
stable groimd has already slid down so that its surface has approached 
the angle of repose. Should slides occur, they are not Hkely to menace 
the operation of the Canal. SHdes, great enough seriously to obstruct 
trafiic in the Canal, could occur only in the Culebra District, which is 
but one mile long. The possibility of great slides in this section has 
therefore claimed the most careful consideration of the Committee. 
