Earth Science
Chapter 1
Section 4
A. Topographic Maps:
1. Topographic Map- is a map showing the surface
features of an area. Topographic maps provide highly
accurate information on the elevation, relief and slope
of the ground surface.
2. Uses of Topographic maps- Businesses, cities and
recreation.
3. Scale- Topographic maps are large-scale maps showing
a close-up view of part of the Earth’s surface. Most
U.S. “Topo” maps are at a scale of 1:24,000 ( 1cm on
the map = 24,000cm (240 meters or .24 Km) of the
Earth’s surface) .
At this scale, details of elevation and features, such as
rivers and coastlines, large buildings, airports and major
highways appear at the correct scale. Symbols are used
to show smaller features such as houses.
4. Coverage- Government agency responsible for creating
topo map is the United States Geological Survey
(USGS). Each topo map covers about 145 sq. miles
at a scale of 1:24,000 or 1:25,000.
5. Symbols- Used on Topo maps to represent features
such as wooded areas, swamps, schools, etc.
B. Showing Relief on Topographic Maps:
1. Contour Line- Lines on a Topo map that connect areas
of equal elevation.
2. Contour Interval- The change in elevation from one
contour line to another
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3. Index Contour- A contour line heavier and darker than
other contour lines labeled with a number indicating the
elevation of that line above sea level.
4. V-Shaped Contours- V-Shaped contour lines pointing
downhill indicate a ridge line. V-Shaped contour lines
pointing uphill indicate a valley and point upstream.
5. Hilltop- A contour line that forms a closed loop with no
other contour line inside it, indicates a hilltop.
6. Depression- A closed loop with dashes (Hachures)
inside indicates a depression.
Define:
Elevation- Distance above sea level
Relief- The difference between the highest and lowest points in an
area.
Slope- Steep or gentle.
C. Global Positioning System:
1. GPS- Global Positioning System
2. Uses a system of 5 to 8 GPS satellites at any one time
to find latitude, longitude and elevation of a point on
Earth.
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