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.
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A contour line is a line drawn on a topographic map to indicate ground elevation or depression. A contour interval is the vertical distance or difference in elevation between contour lines.
It is the difference in elevation between two consecutive contour lines. For a contour map, the contour interval is always constant.
What is the contour interval on a map based on? The relief in the area. The difference in elevation between the highest and lowest points in the area on the map.
How Do You Find the Contour Interval on a Map? Contour intervals tell you the change in elevation between any two contour lines. You can find the contour interval in the map key, usually located underneath the scale of the map at the bottom center.
If the scale is small, the contour interval should be large and vice versa. The general terrain of the area determines the contour interval. For a flat area, the contour interval should be small. For sloping or undulating terrain, the chosen contour interval should be large.
Different maps use different intervals, depending on the topography. If, for example, the general terrain is quite elevated, the map might run at 80- to even 100-foot (24- to 30-meter) intervals. This makes it easier to read the map — too many contour lines would be difficult to work with.
Terms in this set (13) A contour line on a topographic map connects points of equal elevation. The change in elevation from contour line to contour line is called the contour interval. such as 1,600 or 2,000 feet.
The more closely spaced the contour lines, the steeper the slope. You can find out exactly how steep the slope of the area you are interested in by subtracting the lowest elevation from the highest, and dividing the result by the horizontal distance. Horizontal distance is found on the scale.
A topographic map illustrates the topography, or the shape of the land, at the surface of the Earth. The topography is represented by contour lines, which are imaginary lines. Every point on a particular contour line is at the same elevation. These lines are generally relative to mean sea level.
An orthophoto map is therefore a vertical aerial photo on a lower level of 1:10 000, with contour lines added. Contour lines of 5 metres intervals are used in order to identify detail. Even names of places, railway lines and roads are shown on the photo.
contour line, a line on a map representing an imaginary line on the land surface, all points of which are at the same elevation above a datum plane, usually mean sea level. map: contour lines. The diagram illustrates how contour lines show relief by joining points of equal elevation.
How To Read Contour LinesIndex lines are the thickest contour lines and are usually labeled with a number at one point along the line. ... Intermediate lines are the thinner, more common, lines between the index lines. ... Supplementary lines appear as dotted lines, indicating flatter terrain.More items...•