<P> One of the greatest barriers to a canal was the continental divide, which originally rose to 110 metres (360.9 ft) above sea level at its highest point . The effort to cut through this barrier of rock was one of the greatest challenges faced by the project . </P> <P> Goethals arrived at the canal with Major David du Bose Gaillard of the US Army Corps of Engineers . Gaillard was placed in charge of the canal's Central Division, which stretched from the Pedro Miguel locks to the Gatun Dam, and dedicated himself to getting the Culebra Cut (as it was then known) excavated . </P> <P> The scale of the work was massive . Six thousand men worked in the cut, drilling holes in which a total of 27,000 t (60,000,000 lb) of dynamite were placed to break up the rock (which was then removed by as many as 160 trains per day). Landslides were frequent, due to the oxidation and weakening of the rock's underlying iron strata . Although the scale of the job and the frequent, unpredictable slides generated chaos, Gaillard provided quiet, clear - sighted leadership . </P> <P> On May 20, 1913, Bucyrus steam shovels made a passage through the Culebra Cut at the level of the canal bottom . The French effort had reduced the summit to 59 metres (193.6 ft) over a relatively narrow width; the Americans had lowered this to 12 metres (39.4 ft) above sea level over a greater width, and had excavated over 76,000,000 m (99,000,000 cu yd) of material . About 23,000,000 m (30,000,000 cu yd) of this material in addition to the planned excavation, in the form of landslides . Dry excavation ended on September 10, 1913; a January slide had added 1,500,000 m (2,000,000 cu yd) of earth, but it was decided that this loose material would be removed by dredging when the cut was flooded . </P>

Method of us gaining control of panama city to build panama canal