White. Originally designated country too open for hiding a platoon of soldiers on a single acre from aerial reconnaissance. It denotes semi-open or open lands, including rock outcroppings.
Narrow valleys and ravines. Represented by a series of V-shaped lines (the closed end of the V points uphill).
Widely spaced contour lines. Elevation changes gradually.
Saddle or pass. A dip in elevation between lines that show rising elevation, indicated by an hourglass design.
Series. The amount of land covered by the map. A typical 7.5 series USGS map is 7.5 minutes of latitude high (about 9 miles) by 7.5 minutes of longitude wide (about 6 miles). A 15-minute series covering more land in less detail is also available.
High points. The innermost ring of a concentric pattern of contour lines resembling the whorl of a fingerprint. A peak is often marked by an X with the elevation noted.
Green. Woodlands and scrublands with substantial vegetation.
Gray. Privately held lands within a national forest.
Black. Man-made features, including buildings, trails, and secondary paved, gravel, and dirt roads.
Blue. Waterways such as lakes and streams.
Red. Major and secondary highways, as well as surveying lines.
Scale. Marked at the bottom border.
Foot and horse trails. Marked by black dotted lines. As a general rule, allow a half hour for hiking each mile of distance, plus a half hour for every 1,000 feet of ascent.
Declination. The difference between true north and magnetic north. Marked in degrees, it must be taken into consideration for map and compass navigation.
Marshland. Shown by this blue pattern. (The author shot a bull moose in the willows at this very spot.)
Broad valleys. Marked by U-shaped lines with the closed end pointing uphill.
Broad contour lines. These mark greater elevation changes (on this map, 200 feet).
Contour lines. Trace the outline of terrain at equal elevations. On this map, the contour interval (the vertical distance between adjacent lines) is 40 feet.
Closely spaced contour lines. Slopes are steep.
Ridges. These are shaped like a series of Vs or Us pointing toward lower ground.