specialized maps which show the
highs and lows (relief) of the
Earth’s surface
topo map parts…
 Field : A region in which similar
quantities can be measured at every
point or location (ex. temperature in a
room or depth of snow)
 Isolines: Connect points of equal values
on a map
 Contour line: Connect points of equal
elevation
• Index contour: A contour line that has elevation
noted on it. Typically a multiple of five or ten
(example: 300, 320, etc)
• Contour interval: The difference in the height
between two contour lines that are next to each
other. NOTE: A contour interval shows a
difference in vertical height and a map scale shows
horizontal distance
Contour Interval
= 5 feet
Contour interval =
(Index Contour 2-Index Contour 1)/
Number of Lines between
Ex.:
(320-300)/4= 20/4= 5 ft contour interval
…topo map parts
A benchmark is a point where the
actual elevation is known
elevation is shown on the map by
the letters BM and the elevation
next to it (ex. BM1078)
.
 Depression contours show where the
elevation decreases (a hole, volcano crater,
etc.)
 When reading the depression contour, the
elevation of the first one is the same
elevation of the regular contour before it.
The next one decreases the same amount as
the contour interval
Depression
contours are
shown with
dashed lines
inside of the
contour line
circles
Contour lines
Index contour
benchmark
Landforms on Contour Maps
 The steepness of an area is shown by the
closeness of the contour lines
 The closer the contour lines are together,
the steeper the area (cliff, etc.)
 When the contour lines are spread out, the
land is relatively flat.
 A closed circle after a series of increasing
contour lines shows the top of a hill or
mountain
Steep slope
(close lines)
Hill top (circles)
Gentle slope
(spread out lines)
Landforms on Contour Maps
contour line crosses a stream or
river, the contour line bends and
forms a “V” shape
SUPER IMPORANT!!!!!!!!!!!:
 The point of the “V” shows the direction that
the water is coming from
 The “v” points to the SOURCE of the river
or upstream
Note the “V”
shape of the
contour lines as
they cross the
river!
The “V” points
to the source,
so the river is
flowing in what
direction???
Escarpments and Slope
Escarpments: Another word for
cliff
The slope or gradient of the hill can be
determined by using your ESRT
Gradient =
difference in elevation
-------------------------------------------------------------------------------
distance
Some important points
Contour lines are circles within
circles
Contour lines never cross each
other, but they may touch
Contour lines are darker every 5th
line and has elevation printed
Contour lines are not spaced
evenly.
The closer the lines, the steeper the
slope
The smaller the circle towards the
middle, the closer you are to the
top of a hill
Some important points
 Hachured/dashed lines show a depression
or a hole (decrease in elevation)
 The first contour line of a depression is the
same elevation as the contour line which
surrounds it
 When lines cross a stream, they bend
making a “V”
 The “V” points upstream, opposite the
direction of flow.
Profile: side view of the hill/mountain;
drawn by using a contour map and by
plotting the elevations of certain points
on a vertical axis
Making a Profile from a
Topographic Map
a. Lay a piece of scrap paper along the line where the
profile is to be constructed.
b. Make a mark on the scrap paper at the exact place
where each contour line, stream and hill top crosses
the profile line.
c. Label each mark with the elevation of the contour it
represents.
d. On the graph provided, label the horizontal lines with
matching elevations, if not already completed for you
e. Place the scrap paper with the labeled contour lines at
the bottom of the graph and project each contour to
the horizontal line of the same elevation. Make a dot
at this location
f. Connect the dots.
g. Round out hills and valleys- do not draw lines straight
across
Place a paper strip
over the line you
want to draw a
profile of.
Mark clearly each
line of contour of
your line.
Below these
marks, write down
the elevation of
each line of
contour.
Place your paper onto a graph. Copy each point. Connect the dots! EASY!