By Megan and Slade

A topographic map is a map that shoes the surface features, or topography, of the Earth. Topographic maps show both natural features, such as rivers, lakes, and mountains, and features made by humans, such as cities, roads, ad bridges.

Topographic maps also show elevation Elevation is the height of an object above sea level. A federal government agency, USGS, has made topographic maps for all the surfaces in the US. Each map is a detailed description of a small area on the Earth’s surface. They use feet as their units of measure.

Contour lines are used to show elevation. Contour lines are lines that connect points at equal elevation. The shape of the contour lines reflects the shape of the land.

A contour interval is the difference in elevation between one contour line to the next. For example, a map with a contour interval of 20 ft. would have contour lines every 20 ft, of elevation change, such as 0 ft., 20 ft., 40 ft., 60 ft., and so on.

Relief is the difference in elevation between the highest of lowest points of an area being mapped. For example, the closer the lines, the higher the relief, the further the lines, the lower the relief.

An index contour is a darker, heavier contour line that is usually every fifth line and that is labeled by elevation. It is used to make reading the map a little easier.

Topographic maps, like other maps, use symbols to represent parts of the Earth’s surface. Different colors are also used to represent different features of the earths surface. Buildings, roads, bridges, and railroads are black. Contour lines are brown. Major highways are red. Cities and towns are pink. Bodies of water are blue. Wooded areas are green.

When you first read a topographic map it may seem confusing. But knowing the following rules will help you understand topographic maps. Contour lines never cross. The darkening of contour lines depends on slop and elevation. Contour lines that are part of a valley or stream are v shaped. Closed circles indicate a hill, plataou, or depression.

A topographic map, is a map that shows the layout of the land. Elevation is the height of something above sea level. Contour lines are used to show elevation. Contour interval is the amount of elevation between one contour line to the next. An index contour is a darker heavier line every 5 to 10 lines to show elevation.