7/14/2023 0 Comments Topographic map contour interval![]() ![]() If you cut sheets of this to fit your map, you can add all kinds of information, especially if you use multiple sheets of acetate to make your overlays. It is possible to find rolls of clear acetate. Even a cloudy day may add time to a sunny weather estimate the worse the weather, the more time will be added. (You won’t find this “rule of thumb” very many places.) These numbers are for a general estimation only: your actual time may vary according to weather and other factors. If you cross a contour line, it doesn’t really matter if you are going up or down, add five minutes to your time. ![]() When you are laying out a map route, and trying to estimate time and distance for planning purposes: assuming normal undergrowth and decent weather, if you can lay out a straight line on a fifteen-minute map (that’s a 1:50,000 or 1:62,500 map) you can travel the width of your thumb on the map in about fifteen minutes if you don’t cross any contour lines. I thought I might repeat a couple of things I learned and have mentioned elsewhere on this site. Compasses and protractors are just as familiar as the furniture in the living room. I spent a lot of time with maps while in the Army. as long as she was outside take her indoors, and her sense of where directions were was out 180 degrees. My grandmother could easily point out North, South, East, etc. – Very familiar with People who get lost easily. The USGS site, is a nice resource where you can select a location for available map options. It may be a good idea to have several which cover the geography of the land near where you live, or other areas of interest where you may travel. There are countless uses for topographic maps. Here’s a quality classic, Made in the USA. Of course it would help to have a good compass! The unique “V” or “U” shapes along lines of contour will indicate where rivers and streams will likely be (which themselves are typically drawn on the map in blue). By using triangulation you could discover your current position on the map. and then look at your map with that frame of reference in your mind while searching for the same identifiers on the contour of the map itself. For example, if you know that you are within the confines of a given map, you could potentially look around and identify several (3 is good) points such as hilltops, valleys, etc. The topo map may help you locate where you are. Once you allow your eyes to observe the overall pattern of the thick and thin contour lines, it becomes fairly easy to imagine the hills and valleys. The beauty of a topographic map is its ability to infer a picture in your mind of the lay of the land. Topographical Map Contour Lines Visualize The Land So, be aware of that distance, depending on the map you’re reading. Note: A thought to bear in mind when you are using a map out on the ground… The gap between the interval lines – 6m – if a feature on the land is smaller than that height, and situated between two elevation intervals, it may not appear on the map at all. The contour interval is stated on every topographic map and is usually located near the scale.įor example, if a topographic map scale indicates a contour interval of 6 meters (nearly 20 feet), and a particular thick ‘index’ contour line on the map is labeled ‘1040’, this means that everything along that contour line is at 1040 meters elevation above sea level (the newer USGS topo maps are in meters), and each thin line above or below that index line is a difference of 6 meters. The distance represented between each of the interval lines is known as the contour interval. However, index lines (the bold / thick lines) are typically labeled with a number indicating the elevation for that particular line. You’ll notice both thin and thick contour lines on a topographic map. They also trend up valleys and form a “V” or a “U” where they cross a stream. Lines spaced widely apart indicate more gentle slopes. For example, lines that are crowded close together – means that the terrain is steep. Topographic contour lines allow you to figure out general terrain characteristics from their patterns. They are used to determine elevations (referred to in feet or meters, above sea level). By following one, you would travel flat, not uphill or downhill, and would eventually end up back around at your starting point if you went all the way around it. Think of a contour line as a closed loop. They are called contour lines.Īll points along the same contour line are at the same elevation above sea level. ![]() Lines snake their way around a topographic map. Topographic map contour lines represent the land surface. Topography is the shape of the land surface. ![]() It also provides specific details as to the elevation of the surface. A topographic map enables you to visualize the hills and valleys of the land itself. A topographic map is a two-dimensional representation of the three-dimensional surface of the land. ![]()
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