1/8/2023 0 Comments Contour map![]() Red is used for man-made features, like main roads or political boundaries, and purple for new changes or updates on the map that weren’t previously represented. It is therefore possible to quickly discern that a particular route from A to B might be more treacherous than operating at a high altitude-the trek might require crampons, an ice axe, and other materials that might not be readily available once in the backcountry.įinally, black is used to represent man-made objects, including trails. In each of these cases, contour lines are also drawn in blue. Topographic maps use green to denote vegetation such as woods, while blue is used to denote water features like lakes, swamps, rivers, and drainage.Īt higher elevations, mountains may be snow-capped year around, or the terrain may actually be a glacier. The color brown is used to denote most contour lines on a map, which are relief features and elevations. It’s important to know what kind of terrain and environment you’re traveling into and what the map of that area is telling you. Walking up the western face of this hill would be more challenging than traversing the easy foot trail. The indexed contour line to the immediate left is 400’, and the one further left is 350’. In contrast, the bottom graphic shows a hill where the top is at 438’. It intersects two indexed contour lines, but the distance between the indexed contours is pretty significant it’s easy to see that this is a very easy path to navigate with respect to elevation gain. Notice the foot trail along the top image above. The Huntsville quad doesn’t really have any hard elevation terrain (though navigating swamps can be pretty hard). If you’re looking for a true vertical cliff, look for a series of contour lines drawn so closely together that they appear to be a single line. For rock climbing, look for a concentration of contour lines in a single area. For a leisurely Sunday stroll, you might be looking to cross just a few contour lines, or perhaps follow a trail that shadows a few contour lines on the map. The key thing to remember about contour lines is this: The closer the spacing, the more rapid the change in elevation. ![]() They are typically found where there is little change in elevation. These lines do not have their elevation given and are found in sets of four between indexed contour lines.įinally, when the terrain is expansively flat, cartographers will often include supplementary contour lines, which are dashed lines indicating an elevation that is half of the elevation between the contour lines surrounding it. Lighter contour lines, that fall between indexed lines, are known as intermediate contour lines. Typically every fifth contour line is an index. Heavier contour lines are known as indexed contour lines and are normally numbered showing elevation. These paths and segments are presented as elevations (vertical distance above or below sea level) and reliefs (the shape of terrain features on the Earth’s surface). If you’d like to download a PDF of the referenced topo map, it is the Huntsville 7.5 x 7.5 1997 map.Ĭontour lines are imaginary they are map artifacts used to represent paths or segments of Earth at an equal elevation. Note: This article uses the Sam Houston National Forest as its cartographic reference. Topographic maps also represent streets and trails, vegetation, streams, and every type of feature that may positively or negatively impact your ability to navigate through the terrain. The primary purpose of a topographic map is to accurately represent the shape of the Earth’s surface, but the utility doesn’t stop there. The ability to fuse these major factors is the most critical skill one can learn when using a topographic map. There are three major factors that aid in the visualization of terrain from a 2d map: Reading terrain is more about artistic visualization than it is science. Today we’re going to discuss how to read terrain off of a map. Editor’s note: This post was written by Jason Robert and originally ran on ITS Tactical.
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