MAPS The listed maps are the USGS topographic, or topo, 7.5', 1:24,000 series and the 15', 1:62,500 series. At our latitude, the 7.5' maps cover an area of about 7 by 8.5 miles. The Mexican maps are Mexican government topo maps of 20' longitude by 15' latitude, 1:50,000. The peak is located on the first, or principal, map listed for each peak. The other, or auxiliary, maps are needed to cover the usual climbing route from the roadhead. Elevations are obtained from the maps and are given in feet. Meters have been converted to feet by dividing by the factor 0.3048. The code numbers give the geographic coordinates of the southeast corner of the 7.5' maps. They permit location of the topo map on small scale maps such as atlases, Auto club maps and USGS 1:100,000 or 1:250,000 series maps. The first two digits give the latitude, and the next three give the longitude, in degrees. The capital letter designates the latitude in steps of 7.5' from A at 0.0' northward to H at 52.5' and the last digit designates the longitude in 7.5' steps from 1 at 0.0' westward to 8 at 52.5'. For example, the SE corner of the Glass Mtn map (371 18G6) is at 37°45' N , 1 18°37.5'W. A table of these indices for minutes is: 



UTM COORDINATES UTM (universal transverse mercator) coordinates are given for some peaks to define peak location on the given map. UTM coordinates are useful for specifying the location of any point on the map: roadheads, campsites, and points along the climbing route. The UTM coordinate grid is defined by the blue tick marks spaced one kilometer apart along the edges of the older maps and by the grid of fine black lines on newer maps. A location to 100 meters is given by a six digit number. The first two digits are the eastward coordinate obtained from the top and bottom edges and the third digit is the number of tenths of a km to the east of the numbered grid line. The fourth and fifth digits are the northward coordinate obtained from the left and right side of the map and the sixth digit is the number of tenths of a km to the north of the grid line. For example, Pleasant Pt, 274474, is 400 meters east of the 27 northsouth grid line and 400 meters north of the 47 eastwest grid line.. Note that the UTM coordinates go from west to east and south to north. A memory aid is "read right up". Location to a precision of ten meters can be given by an eight digit number in which the third and fourth digits give the eastward fraction of a kilometer to one percent and the seventh and eighth digits give the northward coordinate. KEY 


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