Maps typically show big areas of the earth on small pieces of paper. For this reason, there is no way they can show everything, they must be simplified. One way that maps are simplified is through the use of symbols. Symbols are generic pictures drawn to represent real objects. For example, you may live in a house that has three stories, four wings, two porches, a bay window, a double garage, a deck with a hot tub and a helicopter landing pad. There is no way to show all this detail on a map, so your house is simply drawn as a small, black square.
Your Cumberland map contains dozens of different symbols representing things like buildings, roads, forests, lakes and railroads. Sometimes, it is not immediately obvious exactly what these symbols represent. The function of a legend or a key is to define these symbols. Because so many different symbols are used on a topographic map, the map does not have room for a complete legend, although a small one showing road types is provided. Instead, this legend can be found in a separate pamphlet published by the United States Geological Survey (U.S.G.S) entitled "topographic map symbols." This is a standard legend used by the USGS for their topographic maps. This legend can be found through their website and, also, subsets are published in many texts. See page 638 of the Strahler and Strahler textbook. Your Cumberland map does contain a partial legend, found in the lower right-hand corner. This legend is concerned primarily with different types of roads. In the next lab, we will work with these symbols in more detail.
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