Understanding A Topographic Map : The Basics
Technology has left us all far too reliant on instant data accessible at our fingertips, used without any delicate thought given. Like the basic skills needed to use a compass, a map can (sadly) just as easily stump the best of us. Whether hunting, hiking, camping, fishing or whatever could be bringing you to the wilderness a topographic map is a must. How to use one? Just as important. Using this tool you are able to plan your trip smartly, and avoid any unpleasant surprises - and unlike a regular map, where you mostly see roads and highways, a topographic map provides a more realistic view of the landscape. Topographic maps show boundaries, fields, lakes, vegetation, glaciers, permanent snowfields, mines, caves, shorelines and most importantly contour lines. Contour lines are drawn to show and connect points of equal elevation - if you physically followed a contour line, you would be travelling at a constant elevation. Depending on the specific terrain, each map will show contour lines for certain intervals of increased elevation - Each line may be shown to represent 10, 20, 30 or even 100ft in elevation gain between two contour lines. To make the maps easier to read, look out for the index contour lines - thicker, bolded lines - here you'll see the elevation marked (usually every 5 lines or so is an index line). Another key feature is paying attention to the space between the contour lines (contour gap). If the contour lines are close together, you're looking at a relatively steep slope. If the contour lines have wide spaces (or there are none at all) you're looking at a relatively flat terrain.
For USGS topographic maps, 1:24,000 is the scale most often used. Maps based on metric units use a scale of 1:25,000, where one centimeter equals 0.25 kilometers A 1:24,000 map is large and provides a lot of detail about the area -- it will include buildings, campgrounds, ski lifts, footbridges and private roads on a map of this scale. A larger scale map (1:600) gives you extreme detail of a small area, while smaller scales (1:250 000) gives you a large overview with less detail.
With these basics, you can use a topographical maps to determine if a climb looks too steep for your adventure level; using the map you can plan an easier (or wiser) route around any hills or mountains. As mentioned earlier, following the contour lines from the map your elevation will remain relatively stable. Once you've chosen the best route, look at the scale to find out the exact distance you'll be hiking. This way you'll know the amount of supplies you'll need in your backpack.