Topography
Mr. Cesaire
Martin Van Buren High School
• Aim: How do contour lines describe topography?
• Do Now: Copy down the following definitions:
• Topographic Profile- is a cross sectional view
that shows the elevation of the land.
• Gradient- average slope; is the rate of change in
field values between two points in a field.
• HW- Read the instructions and contour the set of
data points.
• Lab Thursday room 254
Topographic Maps
• Topographic maps shows the elevation of an
area.
• Topographic maps tell the user how high or how
steep an area of land is to sea level (0 m or ft).
• The further apart contour lines, the flatter or less
steep the land.
• The closer the contour lines, the steeper the
land.
• Let’s look at several examples
Topographic Maps
The top part of this illustration
is a profile or side view of the
bottom illustration. Notice how
the contour lines on the left
side of the hill is spread
further apart. The slope is
gentle .
On the right side of the hill,
the contour lines are closer
together. The closer the
contours, the steeper the hill.
http://www.csulb.edu/~rodrigue/geog140/con
tours.jpg
Topographic Maps
Another example of a
contour map and the
complimentary side or
profile view.
What do you notice about
the contour lines and the
steepness of the hill?
The image on the left is
a volcano that has an
increasing contour
interval of 200 feet. But
what happens to the
contour value when it
reaches the rim and
beyond?
On a contour map, you
express a depression
(hole, bowl) with line or
hachured lines. The
interval is the same.
When you have a stream, contour
lines “bend” upstream.
The illustration above is a USGS
topographic map of the area
around Martin Van Buren High
School. Observe the contour
lines behind the school.
What can we tell from the
contours behind the school
that describes the topography
of the land?
Describe
the
topography
going away
from Alley
Pond Park.
What does
the contour
lines tell you
about the
topography
of Alley
Pond Park?
Water Table Contour
• Water Table- the
depth to ground
water
• Where is the
water table the
deepest?
Gradient
• A question that we need to ask is how do
we calculate the change of values
between two points?
• The change in field values between two
points is called the gradient.
• The formula for gradient is expressed as:
• = The difference between point A and
B/The distance between A and B
Gradient=Slope
• We can also think of gradient in terms of
math.