Maps, Aerial Photographs, and Satellite Images - Investigations in Environmental Geology - page 24

2. Construction of a Topographic Profile. Using the contour map
you have just completed, draw a topographic profile along
line X-X'. This profile may be constructed by "dropping"
perpendicular dotted lines from each intersection of a con-
tour line with the profile line, to the same elevation on the
graph paper (Figure 2.6). Then connect the points with a
smooth line. State the vertical scale and vertical exaggeration
in the spaces provided.

b. Would you expect the magnetic declination to be the
same the following year?

c. Explain why or why not.

5. Use Figure 2.8 (inside front cover), the description of sym-
bols used on U.S. Geological Survey topographic maps, and
Figure 2.10, the Bloomington, Indiana, l\ minute quadrangle
(in the color map section at the back of this topic) to answer
this question.
a. What is the fractional or ratio scale?

3. Use either Figure 2.7 or a map supplied by your
instructor to answer the following questions.
a. What year was the map made? Revised?

b. What is the contour interval?

b. What year were the photographs taken that were used
to create the map?

Were later photographs also

taken? If so, when?

c. What is the elevation of the filtration plant below Griffy
Reservoir?

c. What are the UTM values for the southeast corner of
the map? N, E

d. Using the township and range system, locate Payne
Cemetery to the nearest 40 acres (quarter of a quarter
section).

d. What are the latitude and longitude values for the
southeast corner of the map? degrees, min-

utes, and seconds N; degrees, minutes, and

.1/4, ,T.9N., R. 1W.

.1/4, Sec..

seconds W

e. What is the elevation of the major contour adjacent to
the cemetery?

e. What is the scale of the map?

6. Using a topographic map of your local area (provided by
your instructor), fill in the following information:
a. Name of the map?

f. What is the contour interval of the map?

g. What is the quadrangle immediately southwest of this
quadrangle?

b. Contour interval?

h. How many degrees difference are there between true
north and magnetic north?

c. Datum plane?

4. True North (TN) and Magnetic North seldom are exactly
the same and magnetic north changes continually. Since we
use a compass to determine our direction of travel and sight-
ings, knowing the difference between TN and Magnetic
North becomes essential, especially for mapping. In the SW
corner of most maps, the difference in degrees and direction
between these two north indicators is given for the year of
publication of the map. This is known as the Magnetic Dec-
lination from True North.
a. What is the mean magnetic declination on the
Zanesville West, Ohio, map (Figure 10.5)?

d. Year area first surveyed?

e. Fractional or ratio scale?

f. E-W distance covered by map?

g. N-S distance covered by map?