U.S. Geological Maps give in-depth information about an area.
U.S. Geological Survey maps show streets, bodies of water, vegetation and the contours of the surrounding hills, mountains and valleys. Lines, colors and symbols combine to show surface elevation, pathways and recreational features. The three-dimensional maps are used to plan everything from hiking trips to housing construction. To use U.S. Geological Survey maps, you'll need to get familiar with the symbols and color coding, although U.S. Geological Survey cartographers are constantly striving for more intuitive maps.
Instructions
1. Find the revision date of the map. It typically is printed to the left of the scale and tells you how current the map is. This isn't as crucial when looking at countryside or wilderness maps because the landscape isn't as likely to change without development or a natural disaster. In urban settings, the date is more meaningful to keep up with building and road construction.
2. Examine the colors. Green depicts vegetation. Water is blue and densely built areas typically are shades of gray and red.
3. Follow the lines of the map. Curved, straight or dotted, the lines outline contours of the landscape while also sketching out streams and roads. Color coding is key to reading the lines. Black lines show roads and trails, while red is used to mark more significant roads. Brown lines are used to note topographic contours. Purple lines show features in the land that, although not verified by a field worker, have been captured by aerial photography.
4. Look for symbols. Some are easily deduced, like the picnic tables used to show picnic areas or the tents that are used to mark campgrounds. Athletic fields are often noted in a map with a baseball diamond shape. Race tracks are marked with an oval. Flags are used to mark forest headquarters buildings.
5. Check the relief. The thick, curvy lines are called index lines and the number included with them gives the elevation from sea level. Each map will say whether elevation is counted in meters or another unit. Thinner and dotted lines near the index lines show shifts in elevation. Every fifth line is an index line. Comparing the numbers will show you if you can expect to be going uphill or downhill as you travel.
Tags: Geological Survey, lines show, used mark, dotted lines, Geological Maps, Geological Survey maps
