Hunt more, walk less: The anatomy of a topographical map

Friday, April 7, 2017

By Troy Basso

Special to the Tribune

Most Deer and Turkey hunters use maps for one purpose and that is to navigate from place to place. The truth is a U.S. Geological Survey (USGS) map is much more than a navigation or survival tool, itís an awesome scouting tool as well. In recent years, the hand held Global Positioning Systems or GPS have gained in popularity with the outdoor public. The downfall of this electronic wonder is it WILL fail sooner or later. The batteries will die, the canopy wonít let you get a good satellite signal or any of several reasons it just wonít work. A map wonít fail, it does not require batteries, clear view of the sky, or a masterís degree to operate. My first GPS unit is at the bottom of the Ohio River for one of those very reasons. If you own a GPS unit and donít or canít use topographic maps you are only getting about half of the usefulness out of your unitís functionality.

The bottom line is if you want to take your hunting to the next level you have to learn to not only read a map but use that same map to make the most of your scouting time. Many miles of unproductive hunting or scouting can be eliminated if, you can apply both what you see on the ground and your knowledge of game, to a topographic map. A perfect example would be a funnel or travel corridor. Most big game hunters can readily identify these two things on the ground but by having the skills to also find them on a map BEFORE you go into a given area can be the difference between a successful hunt and a nice walk.

Now if you can master map reading, and manage to figure out a GPS userís manual, youíre not only a blooming genius but, you can take your hunting knowledge, your map/GPS skills and combine them to help make you a more effective hunter. I have taken one of my leases and marked all the rubs and scrapes with my GPS for five years, I then download topographic map of the lease. Every year I add to that map. Now I have five years of comprehensive data on one map. Once you do this you will gain a new understanding if how deer travel patterns are directly linked to the terrain in each area. A map is, simply stated, a graphic representation of the earth, drawn to scale on a plane surface. Before you can really understand a map, you must first understand the information contained both on the map itself and the information in the margins of that map. In the margins, you will find the following information.

SHEET NAME - The sheet name is found in the top center part of the map margin, it tells you the maps name. Generally, the name is derived from the largest or most prominent feature on the map.

SCALE - The scale can be found in both the upper left and bottom center margins. The scale will tell you the ratio of map distance to the corresponding ground distance. A map with a 1:25000 scale means that one unit of measurement on the map equals 25000 of the same measurement on the ground.

ADJOINING SHEET DIAGRAM - This can be found on the lower left margin and tells you what maps join to the top, bottom, left and right of your current map.

BAR SCALES - The Bar scales can be found in the center of the lower margin and are rulers used to convert map distance to ground distance.

CONTOUR INTERVAL - The contour interval is below the bar scales and tells you the vertical distance between contour lines.

LEGEND - The Legend is usually in the lower left margin. It contains symbols used to depict prominent features on the map you using. Please note that all map legends are not the same, so never assume you know what a symbol is without first checking the legend.

Once you understand the information contained in a map margin you can then get down to the information on the map itself. Next are the colors you will see on a topographic map. There are numerous colors used but here are the basics and what they represent.

BLACK - The color black indicates man made features such as roads, buildings and surveyed elevations.

RED-BROWN - This is the color is used for relief features such as contour lines.

BLUE - The color blue is used to show water like in lakes, streams, rivers or swamps.

GREEN - Green depicts vegetation such as forests, orchards, or vineyards.