The second most important Norman river, after the Seine, by its length (105.3 miles / 169.6 km) and its flow (27.5 m3 /s at its mouth), the Orne makes its way through Norman Switzerland before crossing Caen and emerging channeled into the English Channel. After traversing the plain of Argentan, the river forms picturesque gorges by superimposing its winding and steep valley in the granites of Athis and the schists and sandstones of Norman Switzerland. A veritable hole in the environment of the high hillocks of the Ancre and Cerisy mounts, it traces a furrow framed by the rock walls of the Parcs, Houlle, and Pain de Sucre near Clécy. A dam has regulated its flow since 1960 at the entrance to gorges very popular with kayakers.