Topographic maps are a little different from your average map. Not only do they show the location of things like roads and trails but once you get the hang of reading them they also help you visualize three-dimensional terrain from a flat piece of paper. Topo maps use three main mechanisms to describe the terrain.

We're going to cover:

• how to read the maps contour line
• how do you understand scale and
• how to read the symbols and colors found in the map’s legend

Contour Lines

Contour lines are what really make topographic maps something special. these lines connect all the points on the map that share the same elevation. by looking at how the contour lines spread out and come together you can get a good sense of what the terrain looks like.

When the lines are packed close together that tells you that the elevation is changing a lot in a short distance so the terrain is quite steep. As the lines spread out the elevation changes more slowly so the slope is more mellow. Contour lines can also help you visualize the shape of the terrain.

For example as the lines form smaller and smaller circles they're probably showing a peak. Spend some time with a map of a familiar area and see if you can pick out terrain features just
by looking at the contour lines.

Every fifth contour line on a topo map is thicker than the others and those thick lines are called index lines. At some point along every index line you'll find the elevation for that line written on the map.

The change in elevation from one contour line to the next is always the same on the map and most maps have either a 40 or 80 foot contour interval. If your map has an 80-foot interval that means that each contour line is 80 vertical feet away from the next. You can find all the specific details about the contour intervals and index lines for your map in its legend.

Scale

Scale refers to the relative distance of the map. For instance the scale of the map below is 1 to 12,000. That means that one inch on the map represents 12,000 inches in reality. Another map of the same region is 1 to 50,000 and covers a larger area but in less detail.

The important thing is that the map with a smaller scale will show a smaller area but with more detail. Understanding the level of detail on your map is handy when planning your route but it isn't much help if you want to calculate distances efficiently. That's why maps also have a small representative scale near their legend. This scale shows you the relative distance of a mile or a kilometer on your map and you can use the edge of a compass or even a piece of string to help figure out just how far away that peak is.

Reading the legend

One of the first things to look for on any new map is the legend. The legend is like the user's guide for your map. It's where the various lines, colors and symbols are defined.

When it comes to the colors on the map the idea is that the darker the color the denser the vegetation. As you get closer to the top of a peak you'll notice that the colors get lighter as the forest thins out. And of course streams and lakes are represented in blue.

Alongside the list of symbols there are a few other important pieces of information like details about the contour lines and the date of the maps most recent revision. This is also where you'll find the magnetic declination for the region which we'll use to set up your compass.

When you combine your understanding of contour line scale and your maps symbols and colors you can almost visualize your whole trip before you go. the next step in becoming a backcountry Navigator is to learn how to use your compass
alongside your map.