Field Medical Training Battalion – West (FMTB-W) Block 3 Practice Test

Contour lines show elevation on a map. Index contours are the bold, labeled lines that mark larger elevation steps and appear at set intervals. Between each pair of index contours, the thinner, unlabeled lines fill in the elevation steps; these are the intermediate contour lines. They aren’t labeled with an elevation themselves, because the elevation is read from the nearby labeled index line and the known contour interval. So the lines that lie between index contours and carry no labels are the intermediate contour lines. Supplementary lines are a different feature used in some maps to add extra detail and are typically dashed, not the standard unlabeled lines between index contours.