Spot Elevations: Marked with an“X” or are shown at many section corners, bridges, road intersections, hilltops,etc.ĭepression Contours: closed contours with hachures (short lines perpendicularto the contour line) pointing toward the lower elevations within a depression.They generally encircle small depressions. On a contour map, gradient is determined along a line or stream course by:ġ) using the contour lines todetermine the difference in elevation between two points Ģ) using the horizontal scale to determine the distance between thesame two points ģ) dividing the vertical difference by the horizontal distance.Įlevation or Altitude = vertical distance between that point and a fixed datum(usually mean average sea level), which by definition has an elevation ofzero.īench Mark:a point whose elevation has been precisely defined by government surveyors.Its location is marked by a small brass plate. Gradient = change in elevation overa specified horizontal distance. It is drawn as a heavy line and is labeled withits elevation. contours represent only the general shape of the land and do not meet the definition of topography per chapter 18.43 of the Revised Code of Washington. A contour of 60. Second Definition: Contour is an imaginary line joining points of equal elevation. Index Contou r: as a general rule, every 5th contour, starting from sealevel, is an index contour. 1) Contour line that is accentuated in thickness and is often labeled with the appropriate measure of elevation. What is Contour Definition of contour: A contour is a line joining points of equal elevation on the ground.All the points lying on a contour will have equal elevation. If an int n, use MaxNLocator, which tries to automatically choose no more than n+1 nice. Learn how to measure, draw, and interpret index contours with examples, quizzes, and worksheets. Determines the number and positions of the contour lines / regions. They show the vertical distance or difference in elevation between contour lines. 6.7).Ĭontour line = line connecting all points of the same elevation.Ĭontour Interval (abbreviated as C.I.) = the difference between two consecutivecontours.ġ) the level of detail neededto be portrayed ģ) the range in elevation or relief of the area to be mapped. Index contours are bold or thicker lines that indicate the fifth contour interval of a topographic map. On most of the maps, each fifth contour line, indicated as a heavier or darker line, is an index line or index contour. Elevation is added to a 2D map via contour lines(see Fig.
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