Published on 5 November 2024

Contour lines: The enigma of terrain profiles

Just imagine yourself surrounded by breathtaking mountain scenery, holding a hiking map as you plan your route to the next mountain hut. While the trail to the hut is marked on the map, you can’t spot it out from your current position.
In this blog post, learn how to read contour lines, calculate differences in altitude, and to identify mountains, valleys, and hills. Become an orientation expert!

Elisa and Oli plan their hike with the help of the national map and make optimal use of the symbols.

Contour lines

Did you know that hikers sometimes must turn back halfway because they overlooked contour lines when planning? Ascents or descents can also prove far longer and steeper than anticipated. To avoid surprises during outdoor adventures, it’s crucial to accurately interpret terrain details, landmarks, and potential hazards on a map.

Examine the map extract around Kaiseregg: tightly spaced contour lines indicate steep slopes. In contrast, the wider gaps between lines on Riggisalp signal gentler terrain.

Features of the terrain such as ridges (1), valleys (2) or troughs (3) can be identified from their course and distance. Basically: The farther apart the contour lines are, the flatter the terrain (4). The closer the contour lines are, the steeper the terrain (5).

To this end, take a look at the map section around Kaiseregg. The lines are very close together here – which means that there are steep passages. In comparison, the distances between the contour lines on the Riggisalp are wider and the terrain is flatter.

Orientation in nature

Forest

Green areas on the map symbolise woodlands, offering shade and rest spots while serving as key landmarks.

Scattered forest / Isolated tree

Several individual dots represent an open woodland (scattered forest). Individual green dots stand for individual trees, aiding orientation and position checks.

Boulder fields

Grey dots mark unstable boulder fields. These challenging zones are often difficult to navigate and require caution. To avoid accidents, it is important to recognise these areas and to plan alternative routes, if necessary.

Contour lines

On Swiss national maps, contour lines are represented by brown lines. In areas with scree or rocky terrain, these lines appear in black, while in lakes or on glaciers, they are depicted in blue.

Equidistance

Now that you can evaluate slope steepness, how do you determine elevation gain? The map’s contour interval – the vertical distance between adjacent contour lines, also known as equidistance – holds the answer.
The following equidistances apply to national maps:

• 1:10,000     =   10 m
• 1:25,000     =   Swiss Mittelland, Jura: 10m/Alps: 20m
• 1:50,000     =   20 m
• 1:100,000   =   50 m
• 1:200,000   =  100 m

Calculation example
The Kaiseregg map extract uses a 1:50,000 scale with a 20-metre contour interval. Each line represents a 20-metre elevation change. Your hike from Riggisalp to Kaiseregg’s summit crosses 37 contour lines. 37 lines × 20 m = 740 m
This equals a total elevation gain of approximately 740 metres.

How steep will the path be, and how many metres of ascent must be tackled? These are questions hikers must ask themselves when planning a route. Understanding contour lines, woodland, and scree is an essential part of map reading.

Whether you’re planning a long hike or a short outing, your knowledge of these features will help you navigate and reach your destination safely.

Map reading is in!

Map reading is not only a useful skill for all outdoor enthusiasts but also helpful for planning. With a bit of practice and the right information, you can organise your trips even better and impress your friends with your expertise. Incidentally, our famous Swiss national maps are among the most detailed and accurate in the world. By the way: it doesn’t matter whether you use the swisstopo map on your smartphone or as a paper map, as the legend stays consistent.

Would you like to know more? Further information can be found in the legend (also called the “key”) for all swisstopo maps: Map reading | swisstopo online shop (admin.ch)