Question

On a topographic map, increasing spacing between successive contour lines uphill represents a slope.

• A. concave
• B. convex
• C. uniform
• D. waning

Hint:

Compare contour spacing at the foot of the slope with spacing near the top; spacing that grows as you go uphill means the ground is steep low down and flattens near the summit.

Answer 1

The Correct Option is B

Step 1: Recall what contour spacing tells us about slope.
On a topographic map, contour lines join points of equal elevation. The horizontal distance between two consecutive contour lines, drawn at a fixed contour interval, is tied to how steep the ground is between them.
Closely spaced contours mean the ground rises or falls quickly over a short horizontal distance, so the slope is steep there. Widely spaced contours mean the same rise in elevation happens over a longer horizontal distance, so the slope is gentle there.

Step 2: Track how the spacing changes as we move uphill.
The question says the spacing between successive contours keeps increasing as we move uphill, that is, contours are close together near the base and get farther apart as elevation increases toward the top.
Close spacing at the base means the ground is steep near the bottom.
Wide spacing near the top means the ground flattens out as it nears the summit.

Step 3: Match this pattern to the standard slope profiles used in surveying.
A uniform slope has contours spaced equally throughout, so the gradient does not change. That is ruled out here since the spacing itself is changing.
A concave slope profile is the opposite case: contours are widely spaced at the base and closely spaced near the top, giving a surface that is gentle at the bottom and steep at the top, like the inside of a bowl.
A convex slope profile is steep at the base, where contours are close, and gentle at the top, where contours are wide, so the ground bulges outward like the rounded top of a hill or dome. This is exactly the pattern described in the question.
"Waning" is not a standard slope-profile term used for contour interpretation, so it does not apply.

Final Answer:
Contours closely spaced at the bottom and increasingly spaced toward the top describe a convex slope.
\[ \boxed{\text{Convex slope, option (B)}} \]