“There is no favorable wind for the one who does not know where he is going.”
Lucius Annaeus Seneca
Understanding the scale of a map
Every map has a scale (for example, 1:25,000) indicated on its cover and in its legend. The first number represents the distance on the map, while the second represents its correspondence on the ground. On a 1:25,000 map, 1 cm on the map corresponds to 25,000 cm in reality, which is 250 m. Maps at a scale of 1:25,000 are preferred for hiking.
Calculate a distance on the map
The scale indicated on the map will help you calculate distances. Indeed, if you have a 1:25,000 map, knowing that 1 cm on the map corresponds to 250 m in reality, you can quickly calculate that 4 cm on the map will represent a distance of 1 km for you. On maps at 1:100,000 and larger, a mileage is also indicated along the roads.
Find north and orient your map
A map is always oriented toward the north. On your map, this will therefore be at the top in the direction of the writing when you hold the map with the text upright. Once you have located your position, a correctly oriented map will allow you to identify the landmarks (peaks, valleys) that you can observe in the field.
Routes, tracks, and trails
Asphalted roads are indicated by two solid colored lines, and in white for communal roads. When the road is closed to motor vehicles, a black cross line blocking the road is represented. Finally, paths are represented by a black dashed line.
Marked routes
The marked routes are highlighted with a dark red line. Important routes will be distinguished from other trails (local trails) for which the line is thinner and often dashed. Finally, the names of the main marked trails are annotated along their path. Here, the red dashed line represents the crossing of the glacier.
Thin lines / thick lines
Marked in orange on the map, the contour lines represent the terrain. A contour line connects all points of the same elevation in the form of a continuous line. The interval between these lines is defined in the legend and is generally 10 meters.
In order to facilitate the determination of elevations, each 50-meter level is marked by a thicker contour line. Between each thick line, 4 thin lines "depict" the relief in 10-meter increments. In flat areas, there may be instances where "sub-contours" in orange dashed lines provide greater precision at specific points.
How to determine the top and bottom of a slope and know if it is gentle or steep?
To distinguish the high from the low of a relief, the first reference is altitude, which is indicated at certain points on the map as well as on some contour lines. These indications allow for visualizing the direction of the slope.
The peaks appear as concentric contour lines that form "a hill," often accompanied by an indication of summit elevation. To avoid any confusion with simple elevation numbers, these are primarily noted on the thickest lines that mark symbolic milestones such as 1600 m, 1700 m, or 1800 m. The map also features geodetic points represented by triangles or black circles with a central dot.
The shaded relief allows for reading the terrain in three dimensions. The darker the shade, the steeper the slope. The intensity and orientation of these shades simulate lighting that helps to understand the relief. With a bit of practice, the combination of shaded areas, rocky zones, peaks, and waterways allows for visualizing the terrain in 3D from a simple reading of the map.
The spacing of contour lines is an essential indicator. Closely spaced lines indicate a steep slope, while widely spaced lines signal a gentle slope or nearly flat terrain. Sometimes, the slope is so steep that the lines overlap, and the map then represents rocky areas.
Rivers, rocks, and glaciers
The color blue is used for water: rivers, lakes, etc... (The blue hatching represents swamps) On high reliefs, when the contour lines are so close together that they become unreadable, the map includes a specific drawing to represent rocky areas and cliffs. Areas of scree or debris are represented by simple small black dots. If the contour lines turn blue, it indicates a permanent snowfield or a glacier. The color green is used for vegetation (depending on the shades of green: forest, plains, etc...)
Human occupation
The salmon-orange pink areas generally indicate urbanized or built-up zones. This includes houses, public buildings, facilities, and sometimes small settlements.
The yellow areas often represent cultivated or open land, such as fields, meadows, or clearings.
The white areas indicate open spaces without dense vegetation, such as rocky terrains, plains or mountainous areas, and open spaces with little or no vegetation (like golf courses, etc...)
And a huge number of artificial elements such as ski lifts, railways, trams, etc. can be found on these maps and are categorized in the legend.
Quadrillage GPS et calcul de coordonnées
Votre carte comporte différents quadrillages de couleur noire ou bleue et des repères dans la marge associés à des coordonnées. Sur les cartes récentes, portant la mention "Système de coordonnées EUREF89-WGS84 pour GPS,, le quadrillage bleu correspond à des carrés de 1 km de côté. D'autres repères et coordonnées sont présents dans la marge (en bleu ou noir) et sur la carte (croix noires fines). Ils permettent de calculer, à l'aide d'une équerre graduée, les coordonnées de n'importe quel point de la carte exprimées en degrés ou en grades.
Legend elements: colors, symbols...
If in doubt, do not hesitate to refer to the legend found on the inner flap of your map. Certain symbols are used to represent specific features (free access cabin or reservation only, shelter, etc.), a line as a boundary of a national park, etc....
Thank you for reading this article, I hope you enjoyed it.
In addition to this article, you can read by clicking : Finding Your Way: A Guide to Evolving Without Losing Yourself