Drawing profile maps Hand out Activity Sheets 2.1. Map A is a topographic map of Mount St. Helens before the 1980 eruptions. Map B is a topographic map of Mount St. Helens after the eruptions. Students compare the completed profiles to see how the eruption changed the size and shape of Mount St. Helens. Using Topographic Maps Topographic maps use contour lines, which are imaginary lines that connect all points at the same elevation.
Contour lines are always parallel.
They never cross. The closer together the contour lines, the steeper the slope. Closed depressions, such as a volcanic crater, are marked with short lines pointing downslope. Every fifth contour line is made heavier and the elevation is always marked. This teacher packet was originally published and printed in 1997.