Leveling Grid

a grid of points on the earth’s surface whose elevations above sea level have been determined by leveling—that is, a geodetic elevation reference grid. The points of the leveling grid are marked on the terrain by bench marks, which are set in the walls of permanent structures or placed directly in the ground at a certain depth. The leveling grid is the elevation basis for topographic surveying, and its points are also used to study vertical movements of the earth’s crust, where determination of leveling elevations is repeated.