In the mountains a drainage gives you a set of guard rails and a set of bounds on a topographical map. Sometimes walking a half a mile in a direction gives you

In the mountains a drainage gives you a set of guard rails and a set of bounds on a topographical map. Sometimes walking a half a mile in a direction gives you perspective on a peak or another feature that you can identify on the map based on the shape and then you can shoot bearings and locate yourself. Also if you follow water downhill you'll reach successively larger bodies of running or pooled water until you reach the sea. I've been on a hike or two with my wife where knowing where the running water is versus where it should be saved us several hours of being lost.