Hello, I'm the OUTDOOR PROFESSOR from DiscoveringTheOutdoors.com/
Here's your outdoor tip on topographic maps.
Topographic maps are your best choice for wilderness travel or other outdoor expeditions into unfamiliar areas. Even if you're moving through what you believe is an established, well-signed area, a topo map is a helpful tool when you want to identify with certainty your position.
Roadmaps only show flat, 2-dimensional views of areas. Even aerial photographs only show distant views of earth features, but provide little identification of that structure. They both can be good to support your general travel, but are limited in providing needed details for unfamiliar areas. Missing will be information such as perspective on elevation in an area.
Most topographic maps include Geological Survey (USGS) quadrangles and can be customized for a variety of purposes. They will have varying colors and be overlaid with contour lines showing elevations. For example, tightly spaced contours lines indicate steep terrain. These maps identify peaks, ridgelines, flatlands, or valleys along with man-made features such as roads.
Topographic maps enable you to envision the appearance of terrain between 2 points so you can plan the best route of travel between them. Contour lines connect points on the map that share the same elevation so you have a 3-dimensional perspective of the landscape. Very close contour lines indicate steep terrain and widely spaced lines indicate level terrain. Contour lines will never intersect.
Contour lines are separated at elevation intervals such as every 20, 40, 80, 100 or 200 feet. The interval used on a given map remains consistent throughout that map and will be identified in the margin of each map. Every fifth contour line is the index contour line and will be slightly bolder and intermittently includes the elevation of all points on that line.
Scale will be on the map included in a horizontal graphic scale. It displays how a measurement on the map (1 inch, for example) equates to miles of terrain covered by the map. Also printed on the map will be the magnetic declination diagram: It will show the difference between magnetic north (indicated by the MN symbol) and true north (or polar north, indicated by a star symbol).
There will be grid numbers displayed around the edge of a map represent two grid systems that can be used to determine your location—either latitude and longitude or universal transverse Mercator (UTM).
Commercial (non-USGS) maps may include additional features that can be valuable to some users:
Highlighted trails
Elevation call-outs
Distances between trail junctions and landmarks
Primitive trails
Backcountry campsites
Springs
Highlighted boundary lines
These additions, even GPS coordinates may be inserted onto maps.
When first looking at a topographic map, it may appear somewhat confusing and not very useful. There are a few rules that topographic contours must obey, however, and once you understand these rules the map becomes an extremely useful and easy to use tool.
This is the OUTDOOR PROFESSOR from DiscoveringTheOutdoors.com/
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References-Additional Reading
Navigation Basics: Compass and Map
http://www.rei.com/learn/expert-advice/navigation-basics.html
Introduction of Topographic Maps
http://geology.isu.edu/geostac/Field_Exercise/topomaps/topo_interp.htm
Topo Maps and Contour Lines
http://geokov.com/education/topographic-maps-contour.aspx
Nature Quotient.
eBook @Amazon.com
Outdoor Professor’s Tips: Exploring the Wonders of Nature
eBook @Amazon.com
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