Contour lines represent lines of equal elevation. Index lines show their elevations above mean sea level. Find the elevation difference between adjacent index lines, and then divide by the number of contour intervals between index lines (usually five) to find the contour interval.
On most maps determining contour interval is easy, just look in the margin of the map and find where the contour interval is printed (i.e. Contour Interval 20 ft). For the maps on this web site, however, the contour interval is not listed because we only have parts of topographic maps, not the whole map which would include the margin notes.
The space between contour lines on a topographical map is a contour interval. The contour interval is an even space that represents an increase in elevation. For instance, if the map uses a 20-foot interval, there are contour lines at zero, 20, 40, 60, 80 and 100 feet.
The contour interval measurement given in the marginal information is the vertical distance between adjacent contour lines. To determine the elevation of a point on the map— a. Determine the contour interval and the unit of measure used, for example, feet, meters, or yards (Figure 10-2). Figure 10-2. Contour interval note. b. Find the ...
Contour interval is the actual change in elevation represented by the space between two adjacent topographic "rings". For example, if there is a contour interval of 20 feet, each topographic line ...
A contour interval in surveying is the vertical distance or the difference in the elevation between the two contour lines in a topographical map. Usually there are different contour intervals for the different maps. Considering the size of the area to be mapped, contour intervals are assumed. In ...
A contour interval is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line. If the numbers associated with specific contour lines are increasing, the elevation of the terrain is also increasing.
This reference line is an index contour. As noted earlier, an index contour is one that is a bolder, darker contour line and has a value written on the line ever so often. First, find the value of the index contour addressed in the question and then follow the line until you see a number associated with the line.