Why contours matter more on the moors than anywhere else

Moorland is wonderfully open country, and that is exactly the problem. A plateau of heather and blanket bog can hide a thirty-metre gritstone edge, a steep-sided gill, or a sudden plunge into a valley until you are standing right on the lip of it. Paths are faint, walls are few, and in cloud the far side of a valley simply disappears. Contour lines are the one part of a map that lets you see the shape of the ground before you commit to it. Read them well and a descent becomes a decision rather than a surprise.

Spacing is everything: reading gradient at a glance

On a 1:25,000 map the brown lines are usually ten metres apart in height. Where they crowd together, the ground climbs or falls steeply; where they spread out, the slope eases. Learning to read that spacing quickly is the single most useful map skill you can build for moorland walking.

A handy check: one centimetre on a 1:25,000 map is 250 metres on the ground. If a single ten-metre contour interval occupies that centimetre, the slope is roughly 1 in 25 — a steady, pleasant pull. Squeeze three intervals into the same space and you are looking at about 1 in 8: hard work uphill, and loose, tiring, ankle-testing ground on the way down.

• Lines merging or touching: a crag, or so close to vertical that you should treat it as one.
• Lines tightly packed: steep ground; expect eroded peat, loose grit and slow going.
• Lines evenly spaced: a consistent slope, often the most predictable ground to descend.
• Lines widely spaced or absent: gentle or flat ground — which on the moors frequently means deep, wet peat.

Crags, gullies and hollows: what spacing alone won't tell you

Gradient is only half the story. Certain symbols warn you about ground that is not just steep but genuinely awkward. Crag symbols appear as a line of black ticks with the ground dropping away in the direction they point; if your intended line runs towards them, you have found a rock face rather than a slope. Closed contours with short inward-pointing hachures mark a hollow or shake hole, and anything falling into one on a bearing is a warning sign.

Gullies are the ones that catch people out. Look for a narrow V of contours pointing uphill, often with a blue stream line running through it. These are the steepest, wettest and most eroded lines on the hill. A gill that looks trivial on paper can be a twenty-metre drop with slippery sides and no way round once you are in it. Note also that a 1:50,000 map leaves out many small crags and boulder fields; if the descent matters, carry the 1:25,000.

The shape of the slope: spurs, re-entrants and convexity

Contours don't just tell you how steep a hill is — they tell you what kind of slope it is. Where a line bends into a V pointing downhill, away from the high ground, that's a spur: a rib of drier, firmer ground with a natural line of descent and usually a decent view. Where the V points uphill, into the hill, you have a re-entrant or gill — the gathering point for water, peat and steepness. Given the choice, descend the spur.

Look too at how the spacing changes as you go down. If contours bunch more tightly lower down, the slope is concave and will steepen beneath you, often exactly when you are committed. If they spread out, the slope is convex and eases off, which is far friendlier. Comparing the top and bottom of a slope on the map takes seconds and saves an awful lot of swearing.

Choosing a line before you commit

Do the thinking standing still with the map flat, not mid-descent with your boots sliding. Pick the broad spur, then work out whether you can contour round at a constant height to reach a shoulder or col instead of dropping straight into the valley. Contouring — traversing across a hillside while holding the same altitude — is one of the most underused skills on British hills, and contours make it easy to plan, because you simply follow the line of a single contour.

Keep a rough tally as you plan: how many contours will you cross, and how far apart are they on the ground? That gives you height lost and average gradient. If the numbers come out at 1 in 4, look again. And remember that the gentlest line is not always the best one: flat, contourless ground on moorland is often a bog, so a slightly steeper but drier rib can be quicker and kinder.

Practising the skill on familiar ground

The best place to learn this is a hill you already know. Before you set off, predict the steepness of a slope from the spacing, then check it with your feet. As you walk, thumbnail the map and tick off contour crossings — each one is a fixed ten metres of height, a reliable check on your pacing and timing.

In mist, holding a contour across a hillside becomes one of the most dependable techniques you have, keeping you out of the valley bottom and away from the crag edge. Add a bearing, a count of contours, and a note of the features you expect to meet, and you will descend moorland with real confidence — arriving where you meant to, rather than where the ground decided to send you.