The contour lines showing the heights above sea-level are the directions along which species spread to form zones.
A record of this series of advances marked upon a flat map of the original country would give a series of concentric contour-lines narrowing towards the mountaintops, which they would at last completely surround.
The RAV4 is constantly fidgeting in a tiresome vertical bounce where most cars, even sporty ones, manage to flatten the contour lines.
isoseismal map, as one draws contour lines to enclose locations having higher intensities.
triangulated irregular network based on the detailed digitisation of contour lines.