Topographic Maps
I. Topographic Maps
A. Topographic maps show the shape and
elevation of the land.
B. They also show man-made features such
as roads, development, trails, etc.
II. Contour Lines
A. Topographic maps use Contour Lines to show
elevation and land shape.
B. A Contour Line is a line on a map that
connects places of equal elevation.
C. The Contour Interval is the difference in
elevation between two consecutive
contour lines
D. Index Contour- a contour line that is
numbered with the elevation.
Contour
Interval
Contour
Interval
0
-
0
-
1st: Calculate the difference between the 2 index contours.
2nd: Count the number of contour lines between the 2 index contour lines
and add 1. (This is how many “Steps” the elevation has changed)
3rd: Divide the difference calculated in #1 by the number of “steps” figured in #2
and you will get the value of the contour interval.
What is the contour Interval?
III. How Topographic Maps are made
A. The land is
surveyed to find the
elevation of the land.
B. A contour interval is
chosen based on how
steep the land is.
C. Lines are drawn
connecting places
with equal elevation.
D. Contour lines never cross or intersect.
IV. Interpreting land shape
A. Contour lines that are
spaced close together
show STEEP land.
Elevation is increasing over
a short distance.
B. Contour lines that are
spaced far apart show
land that is NOT steep (a
gentle slope). Elevation
isn’t changing much in a
given distance.
*Locate the features listed in your notes
VI. Mountains and depressions
A. Contour lines form closed circles
around mountain peaks.
B. An area of depression is indicated with
hash marks pointing in on the circle.
This indicates that elevation goes down.
VII. Rivers
A. Because rivers
erode land, the
area beside a river
has a lower
elevation than the
land around it. This
appears as dips in
the contour lines.
The point of the
dip always points
UPSTREAM, or up
hill.
Profiles