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Colors and gray tones may also be used to indicate elevation above sea level. On color maps, deep green is usually used to depict low-lying coastal land. Light green and yellow are used for progressively higher lands, followed by light brown and dark brown. The peaks of really high mountains are often shown in white (just like snow). Map readers need to understand these color gradations and what they signify; none of us is born knowing that brown means “higher elevation.” Our brain does help, however. Generally, we think of darker colors as representing greater values, so dark brown to show higher elevations makes sense in many of our heads.

Like just stated for color, when gray tones are used in cartography, the general rule is “the darker the gray tone, the greater the value of whatever is being mapped.” Accordingly, and as seen in Figure 5-3c, the lightest shade indicates the lowest-lying land, while deeper shades signify progressively higher elevations.

While spot heights and contour lines identify the precise elevations of precise locations, shadings refer to a range of elevations over an area. Thus, the lightest gray tone on Figure 5-3c signifies land that is anywhere between sea level and 100 feet above sea level.