Why Contour Spacing Matters on a Ridge Day

Contour lines are the most honest feature on any map. They do not care about your plans or your legs. Each line joins points of equal height, and the distance between those lines tells you exactly how steep the ground is. Tightly packed contours mean a rapid change in height – steep ground, possibly a cliff. Widely spaced contours mean a gentle gradient, a shelf, or a broad ridge shoulder. If you learn to read that spacing before you leave the car park, you can pick a line that suits your group, the weather, and your remaining energy.

Spotting Steep Ground Before You Leave the Valley

Start with the map at home or in the car park. On a 1:25,000 map, the contour interval is usually 5 or 10 metres, so you get fine detail. On a 1:50,000 map, it is often 10 metres, so subtle shelves disappear. Either way, look for clusters of lines. A dense band across a ridge flank means a steep push – maybe a crag or a broken gully. A single line running alone across a slope means a gentle break. Count the lines between two points to estimate height gain. Ten lines at 10 metres apart means 100 metres of ascent. If those ten lines are crammed into a few millimetres, you will be working hard.

Also check the shape of the contours where they cross a ridge. On a ridge crest, contours form a V or U pointing downhill, away from the highest ground. If the V is tight and the lines are close on both sides, you have a narrow, steep ridge – exciting but exposed. If the lines are wide on one side and tight on the other, you have a sheltered shelf and a steep drop. That asymmetry is your clue to an easier line.

Reading Ridge Lines – Spurs, Re-entrants and Shelves

A ridge is rarely a simple line. It has spurs – ribs of higher ground pushing out – and re-entrants – gullies or hollows cutting in. Contours show these clearly. On a spur, the contour lines point downhill, away from the main ridge. On a re-entrant, they point uphill, into the hillside. For easier walking, follow spurs where the contours are widely spaced. Avoid re-entrants where spacing is tight, as they often hold loose rock, vegetation, or water.

Look for shelves: places where contour spacing suddenly widens after a steep section. These are natural resting spots and often give a gentle ramp across a steep face. A series of shelves stacked above each other can be linked into a zigzag ascent, keeping you off the steepest ground. On a ridge, a shelf on the windward side might be your best line when the other side is blasted by wind or softened by snow.

Planning an Easier Ridge Line from the Valley Floor

Before you set off, trace your intended ridge line on the map. Mark any sections where contours are tight on both sides – those are your crux points. Then look for alternatives. Can you contour around a steep step on a shelf? Is there a spur that avoids a rocky nose? Use the contour numbers to check your height. If you need to gain 300 metres, pick a line where the contours are evenly spaced over that distance. Even spacing means a steady gradient, which is easier on the legs and safer underfoot.

Make a note of escape routes. A wide contour spacing that leads down into a valley is a potential bail-out. A tight cluster of contours leading into a re-entrant is not. If the weather turns, you want to know which direction gives you the gentlest descent. Practise this at home: cover the map with a sheet of paper, slide it slowly, and predict where the steep ground will be. You will soon spot the difference between a gentle ridge and a rocky staircase.

When Contours Do Not Tell the Whole Story

Contours are a guide, not a guarantee. A 1:50,000 map might miss a 10-metre rock step because the contour interval is too coarse. Vegetation – deep heather, tussocks, or a conifer plantation – does not show on contours, and it can slow you to a crawl. Nor do contours show loose scree, wet bog, or a path that has eroded into a gully. Always cross-check with other map symbols: crags, scree, marsh, and boundaries.

On the day, compare what you see with what you expected. If the ground is steeper than the contours suggested, stop and reassess. If a shelf looks wider on the map than on the hill, trust your eyes. The best ridge walkers use contours to narrow the options, then use their judgement to pick the final line. That habit – reading spacing before you leave the car park, then reading the ground as you go – will keep you moving comfortably on ridges for years.