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PRACTICAL WORK №4
CONTOUR MAPS. DRAWING A TOPOGRAPHIC
PROFILE

PURPOSE
Today's practical work is intended to acquaint you with topographic contour
maps and topographic profiles. The basics of topographic maps, map scales, map

grids, and symbols were covered in previous lab. This time, we will focus on
reading and interpreting these maps for information on elevation, gradient, and
landscape profile.

CONTOUR MAPS
Topographic contour maps are maps that show the changes in elevation
throughout the map area using lines of constant elevation called contour lines.

By means of contour lines the three-dimensional “lay of the land” can be
illustrated in two dimensions on a printed map. Standard Topographic
Quadrangle Maps include contour lines.

CONTOUR LINES
Imagine a small hill in the middle of a field. If we could get our hands on
one of those chalk carts that are used to put lines on athletic fields, then we could

use the cart to draw contour lines on the hill. We would do this by starting at the
base of the hill and pushing the cart around the base, following a level line, but
staying with the edge of the slope at the base of the hill. Then we would measure
10 feet of vertical distance (altitude or elevation) and move the cart to a point on

the hill ten feet above the level ground. Starting from this point we would push
the cart around the hill, never moving up or down the hill, but always staying
exactly ten vertical feet above the level ground. We would go around the hill and
eventually come back to where we started, having drawn a 10-foot contour line.

Now, moving another ten feet up, we would do this again. Another ten feet after
that, and we go around the hill again. If we keep making lines around the hill,
moving up ten feet every time, eventually we will reach the top of the hill.
Chances are that the actual summit of the hill would be a little above the last line

we made, but below the next ten-foot interval.
If we had a sensitive altimeter, we could measure the height of the top of the
hill. Let’s say that we make four lines above the base of the hill (that’s five lines
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