 The trough descends abruptly north of Folly Lake where over a distance of approximately the valley floor levels out at approximately elevation.From there, the valley floor and the serpentine Wallace River gradually descends over the next to approximately elevation at the junction with the West Branch Wallace River.In 1872 the Intercolonial Railway built its mainline between Halifax and Rivière-du-Loup through the valley, rising along its western walls to gain altitude to reach the summit at Folly Lake.