A ball field has few isolines. C. Topographic Maps 1. A map is a two-dimensional model of the earth s surface. Topographic maps are contour maps showing the elevation of the land surfaces. On a topographic map sea level is an elevation of 0 feet or 0 meters.
Contour lines are isolines showing elevation.
D. Reading a Topographic Map 1. Contour lines bend towards a stream. Contour line become smaller as elevation increases up a hill. On most maps every 4th or 5th line is an index line that is labeled. Depressions are marked by contour lines with hachures- little hairs on the contour line.