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quadrangles based on longitude and latitude; (b) the universal metric grid system

or UTM; (c) the United States Land Survey; and (d) the 10,000-foot grid system.
Types (a) and (b) are used extensively in the United States and we will learn how
to use them in this lab. Land -survey maps (c) are used extensively in the western
states and the 10,000-foot grid system (d) is used by the New York State
Department of Transportation.

READING LONGITUDE AND LATITUDE ON A TOPOGRAPHIC MAP
The maps that we will be working with in lab are United States Geological
Survey (USGS) 7 l/2-minute topographic quadrangle maps. On these maps the

longitude and latitude coordinates are given at each corner of the map, and in
thirds along the sides of the map at 2 minute, 30 second intervals (2’30”).
Figure 2 shows the longitude and latitude grid common to all 7 l/2 - minute
topographic maps.

Fig. 2.2 Longitude and latitude grid found on topographic maps

Complete longitude and latitude coordinates are shown at the corners of the

map. Coordinates are also shown at two locations, spaced 2.5 minutes apart, along
each side of the map. Notice that degree values are not shown if they remain the
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