How can you determine whether a slope is steep or gentle, based on the spacing of contour lines? 

Explanation:

Contour: A Contour line may be defined as an imaginary line passing through the points of equal elevation.

Characteristics of Contour line:

• Closed contour lines with higher values inside show a hill.
• The variation of the vertical distance between any two contour lines is assumed to be uniform.
• To contour lines having the same elevations cannot unite and continue as one line. Similarly, a single contour cannot be split into two lines
• The horizontal distance between any two contour lines indicates the amount of slope and varies inversely on the amount of slope.
• The steepest slope of terrain at any point on a contour is represented along the normal of the contour at that point. They are perpendicular to ridge and valley lines where they cross such lines.
• Contours do not pass through permanent structures such as buildings.
• Contours of different elevations cannot cross each other (caves and overhanging cliffs are the exceptions).
• Contours of different elevations cannot unite to form one contour (a vertical cliff is an exception). 
• Equally spaced contour represents a uniform slope and contours that are well apart indicate a gentle slope.
• Closely spaced contours indicate a steep slope.
• Whereas in the case of depressions, lakes, etc the higher figures are outside and the lower figure is inside.