Originally Posted By wandering_daisy


Be aware that if you have a 40-foot contour interval, a cliff or small hill may not show up if its total height is less than the interval. I have run into a lot of surprise 20-foot cliffs that have stopped me cold!


You conceivably could have a cliff nearly eight feet high with the contour interval marking the middle of the cliff. In most terrain, this is pretty rare, because the ground (and the contour lines) will gradually steepen as you approach the precipice.

This may not be the case in southwestern canyon country, where the ground contours can go from dead level to screaming vertical within five horizontal feet. I learned this the hard way.