by April J.

Created on: May 22, 2008   Last Updated: May 30, 2008

Topographical maps, and the skills needed to read them, are powerful additions to any outdoor enthusiast's toolkit. Not only can these maps help campers and hikers plan their routes and find their way, but they can also add to the safety of a trip by helping people to avoid getting lost and pinpoint their location when needed.

What the wide range of topographical maps out there have in common is that they all represent features of the Earth's surface (or its "topography"). Slopes, for example, are represented by contour lines, and other features such as rivers, lakes, roads, and even buildings can also be represented. Each map has a legend to enable the reader to make sense of its symbols, and a grid (for example UTM, latitude/longitude, or both). Topographical maps differ of course in the areas that they cover and the detail with which they do so. The major factor that determines this level of detail is a map's "scale", and this article will focus on the various scales out there, their descriptions, and which purposes are best served by each.

A map's "scale" refers to the distance that a particular length, on the map itself, corresponds to in "real life. The scale is presented in this form: 1:250000, and will be printed somewhere on the map. Depending on the country in which you obtain the map, these numbers may use different units. For example, in Canada a map with scale 1:50000 means 1 cm on the map corresponds to 50000cm on the ground (or 1cm to 0.5km) (4). An American map that advertises the scale 1:24000 likely means 1 inch corresponds to 24000 inches. This difference in units is important to keep in mind in order to be able to properly read and understand the map.

Various countries also differ when it comes to which maps are produced and in which scales. If you are unsure, some research online can help to shed some light on this, and can even direct you to sources where you can purchase or obtain the maps that you need. The Canadian government, for example, produces 2 scales of topographic map (4). The first has a scale of 1:250000 (cm) and provides a general overview, and the second has a scale of 1:50000 (cm) and provides more detail (5). In the U.S., maps are produced by the U.S. Geological Survey, which offers up a wider variety of scales, for example 1:24000 (1 (1:1.6 mile), 1:250000 (1 (1":1 mile)(2).

Another important aspect of scale on a topographical map is the interval of the

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