Final answer:
Contour lines that are close together on topographic maps indicate steep slopes.
Step-by-step explanation:
On topographic maps, contour lines that are close together indicate steep slopes. The distance between contour lines represents changes in elevation. When contour lines are close together, it indicates a rapid change in elevation, which corresponds to steep slopes.
For example, if you look at a topographic map of Devil's Tower in Wyoming, you will see that the contour lines are very close together, indicating the steepness of the sides of the tower.