CGC1D
Part 7: Topographic Maps and Contour Lines
_________________ SCALE
•
We have already discussed horizontal scales: for example: _______________.
______________ SCALE
•
The vertical scale is also known as ________________ __________________.
•
It shows how the ____________ looks in ______ ______________.
•
Contour Lines: Contour lines are used to determine ________________ and are
_________ on a map that are produced from _________________ ____________
of equal __________________ (elevation refers to height in feet, or meters, above
sea level).
•
Every ___________ on a contour line represents the __________ same
_____________.
•
Contour lines can never __________ one another. Each line represents a
____________ elevation, and you can’t have two _____________ elevations at the
same point.
•
Moving from one ____________ line to another always indicates a change in
____________. To determine if it is a positive (__________) or negative
(_____________) change you must look at the contours on either __________.
•
The _____________ contour lines are to one another, the _____________ the
slope is in the real world. If the contour lines are _____________ _____________ it
is a ______________ slope, if they are not evenly spaced
the slope ___________.
•
Creating topographic profiles: Remember that
topographic maps represent a view of the landscape as
seen from ____________. For producing a detailed study
of a ______________ it is necessary to construct a
topographic _________ or __________________
through a particular interval. A topographic profile is a
________________________ view along a line drawn
through a portion of a topographic map.
CGC1D
Part 7: Topographic Maps and Contour Lines
HORIZONTAL SCALE
•
We have already discussed horizontal scales: for example: 1:100,000.
VERTICAL SCALE
•
The vertical scale is also known as contour intervals.
•
It shows how the surface looks in 3-D space.
•
Contour Lines: Contour lines are used to determine elevations and are lines on a
map that are produced from connecting points of equal elevation (elevation refers to
height in feet, or meters, above sea level).
•
Every point on a contour line represents the exact same elevation.
•
Contour lines can never cross one another. Each line represents a separate elevation,
and you can’t have two different elevations at the same point.
•
Moving from one contour line to another always indicates a change in elevation. To
determine if it is a positive (uphill) or negative (downhill) change you must look at the
contours on either side.
•
The closer contour lines are to one another, the steeper the slope is in the real
world. If the contour lines are evenly spaced it is a constant slope, if they are not
evenly spaced the slope changes.
•
Creating topographic profiles: Remember that
topographic maps represent a view of the
landscape as seen from above. For producing a
detailed study of a landform it is necessary to
construct a topographic profile or cross-section
through a particular interval. A topographic
profile is a cross-sectional view along a line
drawn through a portion of a topographic map.
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A profile may be constructed quickly and accurately across any straight
line on a map by following this procedure:
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Contour Lines of a Stream Bed
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HOW-TO GUIDE : Topographic Profile (Cross-section)
1) Pencil the line of your interest in lightly on your map.
2) Place a blank piece of paper along the line you have drawn.
3) On both the blank paper and the map, mark clearly the starting and ending
points of your line of section. Below these marks, write down the elevation of the
starting and ending points of your section.
4) Make a tic mark wherever the paper crosses a contour line on the map. Write
the elevation of the contours
below their tics on your paper.
Make a note of the highest
and lowest points on the
profile for use later.
5) Once you are certain you
have all of the appropriate tic
marks and elevations, remove
your paper from the map. Get
a piece of graph paper that is
at least as long as your line of
section (you can piece them
together if you have to, but
make sure all the grids line
up). Place your paper with the
tic marks on the graph paper
(once again, you may want to
tape it down) and mark the
starting and ending points of
your line of section on the
graph paper.
6) Draw vertical lines above
your starting and ending
points, these will be the
boundaries of your profile.
Use the maximum and
minimum elevations along your
line of section to determine how long to draw these lines.
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7) Beginning with your starting elevation, go directly above the tic mark on your
paper and make a small dot on the graph paper at the corresponding elevation.
Make a small dot for each tic mark on your paper.
8) Connect the dots on the graph paper, and you have a topographic profile! CGC1D
TO DO: Create a cross section (topographic profile) of A to B from this map.
Assume the length from A to B is 500 m. Draw your cross section on the grid.
A
B