What scale? A canyon would likely show differently on a continental-scale map than a local-scale map. What style? A canyon on a contour map is much different than it would appear on a physiographic map. How large is the canyon? The Grand Canyon of the Colorado will probably look different than Bryce Canyon, which would again look very different than a slot canyon. A steep-sided canyon would be drawn differently than one with more gently sloping walls or with a vertical cliff face on one side.
Context is very important for mapmaking.