What is an index contour line on a topographic map?
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. Index contours are bold or thicker lines that appear at every fifth contour line.
What is the difference between index and intermediate contour lines?
Index lines are the thickest contour lines and are usually labeled with a number at one point along the line. This tells you the elevation above sea level. Intermediate lines are the thinner, more common, lines between the index lines. They usually don’t have a number label.
What does an index contour show?
The index contours are a darker or wider line in comparison to the regular contour lines. Elevations are marked on the index contour lines only. To determine the gradient of elevations, observe the amount of space in between the lines. If the contours are placed close together, then you’re looking at a steep slope.
How do you find the index contour interval on a topographic map?
To find the elevation interval between the contour lines, Divide the difference in elevation between the index lines by the number of contour lines from one index line to the next.
What is a intermediate contour line?
A contour line drawn between index contours. Depending on the contour interval there are three or four intermediate contours between the index contours.
How do you find the index contour?
To find contour interval divide the difference in elevation between the index lines by the number of contour lines from one index line to the next. For example, if the distance 200 is divided by the number of lines, where the number of lines is 5.
What is an intermediate contour line?
What is intermediate contour?
Contour lines (thinner lines) between index contours are called intermediate contour lines. In the map shown below, the elevation difference between index lines is 100 meters. The elevation difference or vertical distance between two adjacent contour lines would be 20 meters (100 : 5 = 20).
What are index lines?
Index lines are the thickest contour lines and are usually labeled with a number at one point along the line. This tells you the elevation above sea level. 2. Intermediate lines are the thinner, more common, lines between the index lines. They usually don’t have a number label.
What is an index line?
Index lines are the thickest contour lines and are usually labeled with a number at one point along the line. This tells you the elevation above sea level. 2. Intermediate lines are the thinner, more common, lines between the index lines.
How is elevation shown on a topographic map intermediate contours index contour intervals contour lines?
Contour lines are used to show elevation on a topographic map. Lines or isolines on a map that connect points with the same elevation.