The work on the park began in 1864, under the direction of Alphand, who used all the experience and lessons he had learned in making the Bois de Boulogne and the Bois de Vincennes. Two years were required simply to terrace the land. Then a railroad track was laid to bring in cars carrying two hundred thousand cubic meters of topsoil. A thousand workers remade the landscape, digging a lake and shaping the lawns and hillsides. Explosives were used to sculpt the buttes themselves and the former quarry into a picturesque mountain fifty meters high with cliffs, an interior grotto, pinnacles and arches. Hydraulic pumps were installed to lift the water from the canal of the Ourcq River up the highest point on the promontory, to create a dramatic waterfall.