The Culebra Cut, formerly called Gaillard Cut, is an artificial valley that cuts through the Continental Divide in Panama. The cut forms part of the Panama Canal, linking Gatun Lake, and thereby the Atlantic Ocean, to the Gulf of Panama and hence the Pacific Ocean. It is from the Pedro Miguel lock on the Pacific side to the Chagres River arm of Lake Gatun, with a water level above sea level. Construction of the cut was one of the great engineering feats of its time; the immense effort required to complete it was justified by the great significance of the canal to shipping, and in particular the strategic interests of the United States of America. Culebra is the name for the mountain ridge it cuts through, and was also originally applied to the cut itself. From 1915 to 2000 the cut was named Gaillard Cut after US Major David du Bose Gaillard, who had led the excavation. After the canal handover to Panama in 2000, the name was changed back to Culebra. In Spanish the cut is known as the Corte Culebra and is also called the Snake Cut. Construction French work The excavation of the cut was begun by a French venture, led by Ferdinand de Lesseps, which was attempting to build a sea-level canal between the oceans, with a bottom width of . Digging at Culebra began on January 22, 1881. A combination of disease, underestimation of the problem, and financial difficulties led to the collapse of the French effort, which was bought out by the United States in 1904. The French had excavated some of material from the cut, and had lowered the summit from above sea level to , over a relatively narrow width. American work The United States took over on May 4, 1904. Under the leadership of John F. Stevens, and later George Washington Goethals, the American effort started work on a cut that was wider but not as deep, as part of a new plan for an elevated lock-based canal, with a bottom width of ; this would require creation of a valley up to wide at the top. A vast amount of new earthmoving equipment was imported, and a comprehensive system of railways was constructed for the removal of the immense amounts of earthen and rocky spoil. Major David du Bose Gaillard, of the U.S. Army Corps of Engineers, joined the project