Transcript Contour Lines

Contour Lines
Elevation on Topographic Maps
What is a contour line?
 A contour line on a map is a line that
joins points of equal elevation.
 If you walk along a contour line you
neither gain or lose elevation.
 Measured in metres (in Canada) or feet
(in USA)
Contour Interval
 When drawing in contour lines one must first
know the designated contour interval which
is the difference in elevation between two
successive contour lines.
 Contour intervals vary from one map to
another depending upon the landscape
presented.
 What is the contour interval on this map?
Contour line features…
 When contour lines are spaced further
apart, they represent a gentle slope.
 Closely-spaced contour lines = steep slope
Contour line features…
Some rules for understand topographic maps.
 1. Contour lines never cross.
2. When a contour line crosses a river (stream) the contour
line forms a "V". The "V" always points upstream. This tells
you which direction the river is flowing. Remember water
flows toward the lowest elevation.
3. The slope (gradient) is steepest when the contour lines
are close together and gradual when they are far apart.
4. Contour lines form circles or are lines that go to the edge
of the map. The higher elevations on a map are found where
the contour lines make smaller closed circles.
5. A depression on a contour map is shown by contour lines
with small marks pointing toward the lowest point of the
depression.
Contour Maps to Relief
Maps
 Contour lines help show the shape of the
land
 By layering contour lines one on top of
another, we can create a relief map.
 Relief maps are three dimensional maps that
depict the topography of the earth’s surface.
Challenger BC Relief Map
 The Challenger Relief Map of British Columbia is a
monumental, hand built 80-by-76 foot topographic map
of the province. Built by George Challenger and his
family from 1947 to 1954, it features all of B.C.'s
mountains, lakes, rivers and valleys in exact-scaled
topographical detail.
Residing in the British Columbia Pavilion at the PNE in
Vancouver from 1954 to 1997 it was viewed by millions
of visitors.
 The Guinness Book of Records cites the
Challenger Map as the largest of its' kind in the
world. The map in its entirety occupies 6,080
square feet (1,850 square metres) of space.