contour line

horizontal equivalent

contour interval

contour gradient

2 m

5 m

10 m

20 m

A contour is not necessarily a closed curve.

A contour represents a ridge line if the concave side of lower value contour lies towards the higher value contour.

Two contours of different elevations do not cross each other except in case of an over hanging cliff.

All of the above statements are correct.

steep slope

gentle slope

uniform slope

plane surface

a quick method

adopted for large surveys only

most accurate method

suitable for hilly terrains