Carte des creux et crêtes et des voiries de l’île de Montréal
Map of the island of Montreal showing the current thalwegs closest to the trajectories of former watercourses as they appear on historical maps, the boundaries of the watersheds of each former watercourse, the current road network, the borough boundaries, contour lines ever 5 m simplified, and the QPCS's reference grid.
talweg mapping cartography watercourses stream ridge line crest line watershed thalweg historical map topography altimetry hydrography