​Lesson objectives:

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​,, I can''

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​- Define a contour line on a Topographic map

​- Identify different types of contour line

​- Identify the importance of Contour lines

​Contour lines are the most common method of showing relief and elevation on a standard Topographic map. It is drawn to show places of equal heights. Contour lines we can find only on a Topographic map where they can give us information about elevation, shape and a slope of an area.

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Contour lines are imaginary lines joining places of equal elevation above mean sea level.

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​There are 3 different types of contour lines:

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​1. Index

​2. Intermediate

​3. Supplementary

​1. Index contour lines

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​These lines are ticker than other contour lines and they are labeled with the number of elevation. Index contours occur every fifth contour line.

​2. Intermediate contour line

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​These contour lines are falling between index contour lines, they are finer, tiner than index lines and they don't have their elevations given. There are normally 4 Intermediate lines between two index contour lines.

​3. Supplementary contour line

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​These lines resemble dashes. They show changes in elevation of at least one half the contour interval.