Geography Reference
In-Depth Information
devised. Click usgs250q.shp. These are polygons that represent the United States Geological
Survey 1-to-250,000-scale quadrangle maps. Zoom in on one quadrangle. Using the coordinate
values shown in the lower-right corner of the window determine how many degrees it is from
west to east? ____________. How many degrees from south to north? ____________. Zoom
back to the full extent. Pick a quadrangle at random with the Identify tool, and look at the
attributes. Why do you think there are four possible state names? _________________________
______________________________________________________.
9. Look at the table of usgs250q.shp. Select the QUAD_NAME column. Click Table Options > Find.
Find Boston. Parts of what states would you think would appear on that quadrangle, based on
the ST_NAMEn columns? __________________, ___________________, ___________________,
___________________. Select the ST_NAME1 column. How many quads are contained
completely by Washington State? _________. Just for a diversion, click Globe View. Spin it
around a little. Also notice that a quadrangle in the northern United States covers less land
area than one in the southern United States, since the “rectangles” are defined in terms of
meridians and parallels. Now bring back the Geography.
10. Look at the USGS 1-to-100,000-scale map divisions. What is the name of this feature
class? ___________________. Zoom in on one quadrangle. How many degrees is it from west to
east? _________. How many degrees from south to north? _________. Look at the 1 to
24,000-scale quadrangles. Zoom in on one quadrangle. How many degrees is it from
west to east? _________. How many degrees from south to north? _________. Go to full
extent, then, if you are familiar with the geography of the United States, zoom up on the
southernmost tip of Lake Michigan and determine the name of the quadrangle
there. ____________________________. What is the state? _________________.
11. Examine georef15, which divides the Earth up in to 15-degree by 15-degree “squares.” Also
look at georef1, whose table, together with identifiers from georef15, identifies every one
degree by one degree “square” on the planet. How many such “squares” are there? _________.
12. Click “World Time Zones.shp” and display its geography. Use Identify. What does the ZONE
attribute refer to? _____________________________. How many square kilometers are in the
zone that contains Greenwich, England? 3 _________. From the table: how many time zones are
there? _________. How many would there be if time zones were defined simply by meridians
that were one hour apart? _________. For extra credit: What place relates to a time zone that is
5:45 later than GMT? _________________________________. (Hints: find the polygon, zoom in,
go back to Countries, or use the Internet.)
13. FYI: JOG stands for Jet Operation Graphic. ONC means Operational Navigation Chart. Take a
quick look at each.
The two major reference systems that are left in this list are the United States State Plane coordinate
system of 1983 (ustpln83.shp) and the Universal Transverse Mercator coordinate system (utm.shp).
UTM is a very regular, almost worldwide system. 4 The State Plane system is a set of one or more zones
defined by each state in the United States, and not intended to be used outside that state. You saw some
examples of data sets in these reference systems earlier.
3 UTC (Universal Time Coordinated), previously designated GMT (Greenwich Mean Time), is the basis for all time
zones, so the difference between UTC and time in the city of Greenwich is zero.
4 The areas around the poles are represented with different projections.
 
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