For hunting, hiking, or camping a topographic map of the area is essential to understanding the terrain and plan for the expedition. Of course, to be useful you must be able to understand information presented on the "topo" map.

The basic purpose of a topographic map is to show ground (grade) elevations, also known as topography. However, these maps include much more useful information about the landscape.

Various sizes and styles of topo maps are available. Recommended first stop is web site of the US Geological Survey (USGS) (http://topomaps.usgs.gov/ordering_maps.html). Maps are also available from many private dealers.

USGS provides detailed explanation of the numerous symbols used to represent the landscape (http://erg.usgs.gov/isb/pubs/booklets/symbols/).

TOPOGRAPHY

On a topographic map, grade elevations are generally shown by "contours", which are defined as lines of equal elevation.

In general, contour lines will be shown only for a specific change in elevation (contour interval), such as every 2 feet, 10 feet, or 20 feet. Also, the elevation will not be listed for every contour line. For lines without listed elevation, you must figure the elevation by using the elevations of listed lines and adding or subtracting the contour interval based on how many lines there are from the listed line.

Complete understanding the ups and downs of contours requires experience using topo maps and further reading. However, the key point to remember is that close spacing of contour lines means relatively steep grade, such as a hillside.

A small circle indicates either a local high area (hilltop) or low area (depression). Specific, "point" elevations may be noted within such circles on topo maps.

A series of "V" shaped contour lines indicates a gully, with the "V" pointing uphill.

Contour lines can never cross. However a contour line can appear to end when it runs up against a vertical element such as a retaining wall or a building. For such an event, the "end" of another contour line of the same elevation should appear nearby, but offset.

USGS 7.5 MINUTE SERIES

The most often used topo map is the USGS 7.5 Minute Series.

Basic information is provided along the bottom of the map, including the scale (1 to 24000) and explanatory notes about grade elevations and roadways. On recent maps of this series, the contour interval is 20 feet.

The scale means that 1 unit of measure on the map translates into 24,000 units of that same unit of measurement. For example, 1 inch on the map represents 24,000 inches out in the field, which of course is the same as 2,000 feet (dividing by 12 inches per foot).

On most (but not all) maps, thin straight black lines in each direction divide the map into a grid of squares. Each line is numbered along the sides of the map with either a partial longitude (across top) or latitude (down side). The side of each square is about 3,250 feet or 0.61 miles (just over 6-tenths).

Type of terrain is noted by colors; blue for water, green for vegetated areas and red or gray for built-up areas.

Text identifies place names and various features such as roads, streams, and landmarks.

In areas away from closely-spaced buildings, individual buildings are shown in black.

TERRAIN FOR HUNTING TURKEY & DEER

One man's description of hunting for turkey in Missouri notes that you must choose your position in terrain that prevents the turkey from seeing you too soon (http://mdc.mo.gov/conmag/2007/03/20.htm). The topo map provides essential information to select different potential area suitable for this strategy.

As noted by a Midwest Hunter deer tend to favor "the wooded creek bottom, connecting many small wood patches."