PUZZLE IN PANAMA — BOWMAN 



423 



Not being blessed with these data nor with our present knowledge 

 of soil mechanics and engineering geology, the designers of the present 

 canal, whose decisions on so many vital matters have stood the test 

 of time, used bank slopes of 3 horizontal to 2 vertical for all materials. 

 For any new canal, slopes will be varied, and there seems to be com- 

 plete confidence among the investigators that both safe slopes and 



FiGxiBE 7. — Geological sections across the Isthmus of Panama at the Canal Zone 

 indicating the types of formations to be excavated to convert present canal to 

 sea level. 



bearings pressures can be set, and that correct construction procedures 

 can be outlined, certainly for any canal in the vicinity of the present 

 one. 



For one thing they have determined that the Cucaracha clay, the 

 famous slide material, will stand on relatively steep slopes (1 vertical 

 to 3 horizontal) when it occurs alone, which is about the same as for 

 the similar but harder Culebra formation, but that if overlaid by such 

 hard and heavy rock as agglomerate or basalt the Cucaracha slopes 



