say that you need to go downhill or downstream. But a trail need not necessarily go downhill all the time. It might be flat, it might go uphill and downhill later
isn't that a flawed assumption to make? What if the trail goes uphill for a while and then crosses a small hill to go down to the actual trail head?
In the western ghats, India, if you were to find a trail in a forest, there's no way to determine which could be the right direction based on the inclination of the trail. We cross so many small hills on trails that you could be moving in the opposite direction when you actually decide to go downhill.
