Ridges Look Simple And Hide Their Navigation Problems

Ridge walking is regarded as straightforward navigation. The line is obvious and the ground falls away on both sides. The errors it produces are correspondingly large.

The obvious line stops being obvious at a junction

Ridges branch. At the point where a subsidiary spur leaves the main crest, both continuations look identical from the ground, and both descend away from you.

In clear weather the surrounding terrain resolves this immediately. In cloud there is no information beyond the ground within a few metres, which offers no way to distinguish them.

A walker who takes the wrong branch is committed quickly, because each step down the spur makes the return climb larger and the sense of progress more convincing.

Descending is where the error happens

Ascending a ridge is self-correcting, since converging ground brings a walker back to the crest whatever line they take. Descending does the opposite.

Diverging ground means a small deviation at the top becomes a large one lower down, and the walker ends in a different valley from the one intended.

This asymmetry is why routes that were straightforward on the way up become genuinely serious on the way back in deteriorating visibility.

Cornices and edges are not where they appear

In winter, wind builds snow out beyond the rock edge on the leeward side. The apparent crest is a projecting shelf with nothing beneath it.

The failure line is well back from the visible lip, so keeping a comfortable margin from the edge is not sufficient in itself.

The practical response is to stay on the windward side and to treat the whole edge as unreliable, which frequently means walking on the more exposed and less pleasant flank.

Wind decides which side you can walk on

A ridge concentrates wind, accelerating it over the crest. Conditions on the top of a ridge are routinely far stronger than on the approach, and the difference appears suddenly.

Crossing from one side to the other in strong wind is the moment people are blown off balance, because the sheltered side gives no warning of what is happening above.

Where wind makes the crest untenable, the options are to traverse below it, which may be steeper and less stable ground, or to turn back.

Bearings need to be set before the cloud arrives

Identifying the junction and noting the bearing for the correct continuation costs a minute at a summit and is nearly impossible once visibility has closed in.

Experienced parties on long ridges work through the junctions in advance, so that in poor conditions the decision is a matter of following a prepared line rather than interpreting ground that all looks the same.