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A topographic map is a detailed and accurate illustration of man-made and natural features on the ground such as roads, railways, power transmission lines, contours, elevations, rivers, lakes and geographical names. The topographic map is a two-dimensional representation of the Earth’s three-dimensional landscape.
- Contour Lines
- Identifying Features with Contour Lines
- Topo Map Scales
- Distance Scale
- Map Legend
- Declination
- Map Grids
- Find Topo Maps
Contour lines are the primary and most important feature on a topo map. They show the shape of the terrain, including its hills, slopes, and depressions, by tracing a constant line of elevation on the map that corresponds with the landscape in the real world. Think of contour lines as imaginary horizontal planes sliced through the terrain surface.
Contour lines show more than just the steepness of a slope or the elevation of a peak. You can pick out major land features on the map by the way the contour lines are shaped. 1. Peak: A mountain or hill that is marked by concentric contour lines. The summit may be marked with a name, an “X”, or an elevation. 2. Valley: A landform with a depression...
Map scale is important because it tells you how detailed a topo will be. Map scale is defined as one single unit of measurement equal to a definitive number of the same number of units in the real world. You’ll find the map scale written as a ratio in the bottom margin of a topo map. Map scales vary greatly across different topo maps, but the most ...
The distance scale in the margin identifies the distance on the ground in relation to a straight line on a map. For example, in a 1:63,360 map, one inch on the map equals one mile on land. On a larger scale 1:24,000 USGS quadrangle map, as referenced in the photo above, one inch on the map equals 2,000 feet on the ground. This is important when you...
A map legend explains what the map’s symbols, lines, and colors represent. Look for the legend in the margin or in the corner of a map. On gaiagps.com, click on the map’s thumbnail in the layers menu to access the legend. Large scale USFS recreation maps often include a robust legend with keys for recreation symbols, like campgrounds and restrooms....
Topo maps are oriented to true north, while your compass needle is drawn to magnetic north. Declination is the angle of deviation between the magnetic north and true north. This angle is often depicted in the bottom margin of the map or on the map itself, as seen in the photos below. These diagrams show the declination for the area on the map. Map ...
Township and Range
Many maps have grid lines with the numbers 1-36 written in the middle of each box. These numbered boxes are called sections and originate from the township and range survey method that was used throughout the western United States, some midwestern states, and Alabama and Florida. Each square on the map represents one-square-mile on the ground, conveniently giving you the ability to assess distance without having to use the distance bar.
UTM Coordinates
Some maps, like National Geographic Trails Illustrated, display the Universal Transverse Mercator (UTM) coordinate system, which includes markings on the map for every 1,000 meters on the map’s north-south line and east-west line. The measurements on the north-south lines are “northings” and represent the number of meters that point on the map is from the equator. The numbers on the east-west lines are “eastings” and they depict the number of meters east or west of a particular reference line...
Latitude and Longitude
Latitude and longitude coordinates are also listed in the margins of most topographical maps. They present in the form of degrees, as shown in the picture below.
The USGS has been producing topographic maps since 1879 and has produced some 54,000 maps that cover the topography of the entire lower 48 states and Hawaii. These maps are referred to as the USGS quadrangle maps, with each map covering a 7.5-minute section of latitude and longitude on the globe. USGS quad maps, scaled at 1:24,000, are still consid...
Printed maps will tell you the interval on the map key. In this case, it's 80 feet, so every fainter line is 80 feet higher or lower than the one next to it. Most topographic maps have an index line for every 5th line. If you have a printed map, look for the contour interval listed on the bottom.
The National Topographic System provides general-purpose topographic map coverage of the entire Canadian landmass. These maps depict, in detail, ground relief, drainage, forest cover, administrative areas, populated areas, transportation routes and facilities, and cultural features. They are available in two standard scales, 1/50 000 and 1/250 000.
Answer: Identify as many features around you as you can, whether cultural or natural, and locate those same features on your map. Then orient the map so that it corresponds to the ground features that you have identified. If you have a GPS position, you can use the geographic or UTM grid reference system on the map to determine where you are.
Compass Bearings. Using a compass along with a topographic map ensures an exact direction for locating features. An approximate but quick way to orient your map is to align the compass needle (when it is pointing north) with the top of the map. Remember that north is always at the top of an NTS map. Get more information!
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Jan 26, 2024 · Here are just a few details a topographic map may bring to light: Elevation changes, which are shown through contour lines. Streams, rivers, lakes, and various other important bodies of water. Mountains, forests, tree cover, and other large natural features. Trails, roads, railroads, and other major transportation infrastructure.
