Topographic Maps (Continued)
Another universally agreed upon grid system is the Universal Transverse Mercator. We will not concern ourselves here with the details of this grid system. It is based on subdividing the areas of longitude into zones 6° wide and then measuring the distance in meters from a designated starting point.
If you examine the text at the bottom of the left side of the Cumberland map, you will see that it identifies this quad as being in UTM zone 17. The black grid superimposed on the map is the UTM grid. The black multi-sized numbers and letter for the direction are the UTM coordinates. Comparing the scale and
the black grid, you should identify that each square is 1000 meters or one kilometer. Since this grid is provided on this map, for identification and location purposes, we will use this coordinate system. Locate the point 39° 40'N, 78° 50'W. Looking at the left side of the map, you can see that 39° 40'N falls between the line marked with a
tiny 43 and larger 92 as a number and a tiny 43 and a larger 93. Further examination reveals that on the right side of the map near South Cumberland is the more detailed indication of small 43 large 90 and small 000mN. This means that this line is 4,390,000 meters north of the "false origin" for this zone.
For simplicity, most of the grid markings on the map omit the 000mN designation. Within the square, we can use the graphic scale to measure the distance. The east-west dimension of the system works the same way. The UTM coordinate of the point identified by latitude and longitude would be written 685,875 meters
east, 4392800 m north, Northern Hemisphere zone 17. It will suffice for us to just give the eastings and the northings since we know we are in the Northern Hemisphere and, with just this one map to reference, we can also dispense with repeating the zone designation.
What is located at 691,500 m E, 4,392,400 m N? Answer
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