Agriculture Reference
In-Depth Information
The first features usually noticed on a topographic map might be
the contour lines, shown in brown. Other major features such as vege-
tation (green), water (blue), and densely built-up areas (gray or red) are
easily recognized. A grid also overlies the entire map. The grid generally
represents a one-mile-square unit. This unit is an administrative land
parcel system referred to as a section. Geodesic lines will also be evi-
dent, a universal land system established throughout the United States
by the U.S. Geological Survey.
Both natural and man-made features are shown by lines that
may be straight, curved, solid, dashed, dotted, or in any combination.
The colors used generally indicate similar types of information: topo-
graphic contours (brown); lakes, streams, irrigation ditches, and other
water-related features (blue); land grids and important roads (red); and
other roads and trails, railroads, boundaries, and other cultural features
(black). Again, refer to a map's legend, or go to the USGS website for leg-
end clarification.
Names of places, including cities, towns, counties, and other places
or prominent landscape features, are shown in a color corresponding
to the feature type. Many features and place names are identified with
labels, such as Old Faithful Village, Mississippi River, Los Angeles, Sub-
station, or Golf Course.
u.S. GeoLoGicaL Survey and ScaLeS of
other countrieS
Most countries of the world have established a national map system
similar in many ways to that of the United States. While the maps pro-
duced by various countries have much in common graphically, unique
variations do exist. One should refer to the map legend to better under-
stand the information presented. One of the distinguishing features of
various countries' map systems is whether maps use the metric system
of measurement or the imperial (feet and inches) system. The United
States is one of the few countries still using the imperial system.
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