Typical examples are highway maps of the smaller states and many nineteenth-century county maps and atlases. Where development was sparse, they may be all that's available, and will provide the needed degree of detail. Typical examples are world atlas maps and highway maps covering the larger states. Many of them were made at the turn of the century, and they may show the churches and rural schools our ancestors attended or the houses in which they grew up. Each series of maps will have its own set of symbols, shown in the margin or on a separate accompanying sheet, or on a page at the beginning of an atlas.
Many symbols are international in use or vary only slightly from map to map.
Land form symbols, often shown in brown, take several forms. Modern large-scale topographic maps use contour lines, which run around a hill in such a way that the line is always at the same height above sea level. If we traced a contour line on an actual hill and walked along it, one foot might be lower than the other, but we would neither climb nor descend as we followed it. The further apart they are, the more level the land. Water features, often shown in blue, show everything from oceans, rivers, and canals to intermittent streams that run only after a rainstorm.