A topo map is a type of mapping tool that provides information on the terrain, physical features and natural resources in an area. This can be used for hiking or surveying land before you buy it. In order to understand how to read a topo map well, here are some tips from experts at Dyrt:
The “how to read a topo map for hunting” is a guide that gives an overview of how to read a topo map. The article also provides information on how to use the map and what types of maps are available.
Note from the editor: This article was first published on ITS Tactical and was authored by Jason Robert.
We’ll talk about how to interpret topography from a map today. It’s more about aesthetic vision than science when it comes to reading topography. The depiction of topography from a 2d map is aided by three primary factors:
- Lines of Contour
- Colors
- Shading
When utilizing a topographic map, the ability to combine these primary aspects is the most important skill to master. A topographic map’s principal goal is to properly portray the contour of the Earth’s surface, but its value does not end there. Streets and pathways, foliage, waterways, and any other element that may affect your ability to move around the environment are all shown on topographic maps.
The Sam Houston National Forest is used as a cartographic reference in this article. The referenced topo map is the Huntsville 7.5 x 7.5 1997 map, which you may download as a PDF.
Lines of Contour
Contour lines are fictitious; they are map artifacts that portray equal-elevation pathways or parts of the Earth. Elevations (the vertical distance above or below sea level) and reliefs (the contour of topographical features on the Earth’s surface) are used to represent these pathways and segments.
Contour lines aren’t all created equal. Indexed contour lines are thicker contour lines that are usually numbered to represent elevation. Every sixth contour line is usually an index.
Intermediate contour lines are lighter contour lines that lie between indexed lines. These lines are found in groups of four between indexed contour lines and contain no elevation information.
Finally, cartographers will frequently provide extra contour lines, which are dashed lines indicating a height that is half of the elevation between the contour lines around it, when the terrain is expansively flat. They are usually found in areas with minimal elevation variation.
The most important thing to understand about contour lines is that the closer they are spaced, the faster they change height. You may want to cross a few contour lines on a Sunday walk, or perhaps follow a route that shadows a few contour lines on the map. Look for a cluster of contour lines in a single place while rock climbing. Look for a set of contour lines drawn so close together that they seem to be a single line if you’re searching for a truly vertical cliff.
There isn’t much challenging elevation terrain in the Huntsville quad (though navigating swamps can be pretty hard). Take note of the footpath in the top photograph. It crosses two indexed contour lines, but the space between them is rather large; it’s clear that this is a relatively simple route to follow in terms of elevation increase.
The lower image, on the other hand, depicts a hill with a peak elevation of 438′. The contour line to the immediate left is 400′, and the one to the left after that is 350′. Walking up the hill’s western face would be more difficult than using the simple foot track.
Colors on a Topographic Map
It’s critical to understand the geography and surroundings you’ll be going through, as well as what the map of the region indicates.
Most contour lines on a map, which represent relief features and elevations, are colored brown. Green is used to indicate vegetation such as woodlands, while blue is used to indicate water features such as lakes, marshes, rivers, and drains on topographic maps.
Mountains may be snow-capped all year at higher altitudes, or the landscape may be a glacier. Contour lines are also painted in blue in each of these examples. As a result, it is easy to rapidly determine if a given path from point A to point B is more dangerous than operating at a high altitude—the walk may need crampons, an ice axe, and other equipment that may not be easily accessible once in the wilderness.
Finally, man-made things, such as trails, are represented by black. Man-made elements, such as key roadways or political borders, are depicted in red, whereas fresh alterations or updates to the map, which were not previously represented, are portrayed in purple. Purple is no longer used on newer maps, but since there are so many older maps, it’s worth noting.
Lake Ravens is a lake feature at the bottom of the Huntsville quad and is coloured in blue. The strong red line demarking a political element, the state park border, should be noted. The picture is tinted green for the most part, indicating that this portion of the map is densely forested. Contour lines, as well as two other kinds of routes, are shown in brown: an unimproved or 4-wheel-drive track with parallel dashed lines, and a foot trail with a single dashed line.
Although it is outside of our topographic focus, the USGS has substantial material on the use of colors (and shading) to indicate geologic characteristics. This might be very beneficial for anyone who are interested in rock climbing or geology in general. For further information, see the USGS Colors and Patterns for Geologic Maps. If I ever have the chance to spend a few weeks in southern Utah, I’ll carry a geologic map along with my topographic map since I appreciate knowing that I’m staring at Jurassic or Cretaceous rock.
Shading
Color resemblance between features does not imply that they are identical. The Prairie Branch, another name for a creek, is located just north of Lake Raven. Kill, run, fork, and brook are some of the other names for a stream. Prairie Branch is unique in that it has resulted in the creation of a woody marsh or swamp.
It could be tough to cross Prairie Branch. Expect to see water moccasins, copperheads, and the odd alligator in the Sam Houston National Forest, as well as all of the other pleasant species that make it home.
The process of memorizing map colors is relatively simple, but remembering map shadings is significantly more challenging due to the vast amount of possibilities. Keeping the USGS Topographic Map Symbols–just two pieces of paper–behind your map may be a lifesaver in this situation. Prairie Branch is definitely a submerged woodland marsh or swamp, according to page four of the pamphlet.
Association of Terrain
The practice of orienting the map entails rotating the map such that north on the map corresponds to north in the actual world. The ability to point in a direction and know with certainty what landscape is ahead is dependent on how a map is oriented. But how will you know where you’re going if your compass fails?
It occurs! You could be in the wilderness with a map, but that recent rock face fall (more like a slide) damaged your compass. So, what’s next? The key is terrain association, which is the ability to interpret the environment and position your map. This work is much simpler in mountainous or hilly places than in areas with little to no reference, such as the plains or a rain forest with an obstructed view.
Because the Huntsville quad isn’t like the Rocky Mountains, it’s more difficult to orient a map because you can’t just glance around and pick out the highest peaks. That doesn’t rule out the possibility of orienting the map. Have you noticed how the map aids you in visualizing a valley? Close your eyes and picture yourself standing in a level valley at the ‘n’ in Robinson, then turn to face east.
The valley isn’t extensively vegetated, according to the map, since it isn’t in green, but the hills to the east are. The contour lines also show that there is a substantial elevation difference of roughly 100′. The image of a slinking, quickly ascending series of hills with at least four unique faces becomes plausible. (I’ve marked “YOU” on the map to indicate your location, as well as four red arrows to indicate the faces to imagine.) Valleys are generally simple to see since they usually have a water feature flowing through them; the water feature is usually what carves out the valley.
Two hills may be seen sitting across from each other in the photograph above. The elevation shift isn’t as extreme as in Utah or Colorado, but it’s still a saddle. Looking for concentric rings with a gap between them is the key to spotting a saddle. A saddle, according to someone, may be compared to a frying pan with two eggs in it. There’s the pan’s surface, then an elevation climb to the egg whites, and finally the yolks at the summit of the two hills. The saddle is the dip between two sections of higher terrain, and this is a ridiculous yet efficient method to grasp it.
Hills are also visible on a map, where they are shown as single concentric circles. The image above shows a relatively little hill that rises just approximately 20 feet above the surrounding plain.
Reading landscape isn’t tough, but it does need the ability to shut your eyes and imagine the surroundings on occasion. Cliffs, spurs, depressions, ridge lines, and draws are some of the other terrain characteristics that may be seen on a topographic map.
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