Topographic maps, or contour maps, show the earth’s surface in a series of contour lines indicating elevation. The contour interval indicates steepness, and other geographic data is also included. Contour lines are drawn in brown, major roads in red, and waterways in blue.
The term topographic map is short for the longer topographic map. Topographic maps, also known as contour maps, are maps that show the earth’s surface in a series of contour lines. Contour lines refer to the elevation of a given point, and the lines are drawn in a series of ranges showing mountain heights, ocean depths, and slope steepness. Topographic maps usually give a reference surface to any given map and contour lines are drawn from that point. For example, in Hawaii, the reference surface would be sea level, while in Colorado it could be a low river valley or the lowest point in the state, depending on the map size.
Contour lines on topo maps always have an equal elevation line, which means that if a topo map is drawn for a particular hill or mountain, any given elevation will have a contour line corresponding to that elevation and the line will not will ever cross. Elevations are usually printed on topographic maps right along the edge of the contour line, or sometimes overlapping them. Contour lines drawn very close together indicate steep slopes, while those drawn few and far apart indicate a generally flat ground surface.
Contour lines on topographic maps vary significantly across the contour range. The contour interval indicates the steepness of a slope. On a topographical map representing a steep mountain slope, for example, the contour interval may be 100 feet (30.48 meters) or more, meaning there is a 100-foot (30.48 meter) elevation change. between each contour line. Topographic maps representing flat terrain might have a contour range of only 10 feet (3.48 meters).
Topographic maps aren’t limited to contour lines for mountains, slopes, and plains. Other geographic data is also typically printed on topographic maps, such as rivers, lakes, and canals, as well as significant roads, railroads, property lines, and hiking trails. Topographic maps even have symbols for campsites and buildings, although often a highly populated area is simply depicted with a darker color tint on the map; in this way it is still possible to view the elevations below the streets and structures of the city.
Contour lines on topographic maps are usually drawn in brown, major roads in red, other roads and trails in black, and waterways in blue. Topographic maps designed to show the slopes and contours of the ocean floor have contour lines known as depth contours. Not surprisingly, these contour lines are drawn in blue or black.
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