The guidebook printed a picture of the walk before it printed a word about it. It was not a map. It was the profile — the height of the path drawn against the distance walked, so that the whole day appeared as a single line rising and falling.
Experienced walkers read that line before anything else, and they read it in three places.
First the two ends. If the line leaves the page high on the left and high on the right, the walk begins and finishes on high ground, whatever happens between. If it leaves low on one side and high on the other, you are climbing all day in one direction and the return will not be the same walk.
Then the places where the line meets the river. At one point on this walk the path comes down, touches the water and turns back up without crossing — a stone beach where you stop for lunch and go back the way you came. At another the line goes straight through the water and out the other side. That is a ford, and you need dry socks in your bag.
The difference matters more than it looks. Both places touch the river on the page. Only one of them gets you wet.
Last the turns. Every time the line stops rising and begins to fall you have reached a summit, and a line with four turns has four of them, whatever the guidebook's text promises about a gentle afternoon.