8 Drawing Contour Lines Worksheet - Free PDF at worksheeto.com - Free Printable

Let’s solve this step by step.

We are given a topographic map with contour lines and labeled points A, B, C, D. Elevations are in feet. We see two labeled elevations: 500 ft (on the outermost visible line near point D) and 1100 ft (inside the innermost closed loop).

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Step 1: Find the contour interval

Contour interval = difference in elevation between adjacent contour lines.

Look at the known values:
- The innermost labeled line is 1100.
- The outermost labeled line we can clearly associate is 500.
- Count how many contour lines lie between them (including the ones they’re on? No — count the *intervals* between lines).

From 500 to 1100, let’s trace the lines inward:

Starting from the 500 line (which passes near point D), moving inward toward the center:

Line 1: 500
Line 2: ?
Line 3: ?
Line 4: ?
Line 5: ?
Line 6: 1100

Wait — actually, let’s count the number of spaces (intervals) between 500 and 1100.

If you look carefully at the map:

From the 500-ft line to the 1100-ft line, there are 6 contour intervals.

Because:

500 → next line → next → next → next → next → 1100

That’s 6 steps.

So total elevation change = 1100 - 500 = 600 feet

Number of intervals = 6

Therefore, contour interval = 600 ÷ 6 = 100 feet

✔ So, each contour line represents a 100-foot change in elevation.

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Step 2: Assign elevations to points A, B, C, D

We know:

- Point D is ON the 500-ft contour line → so elevation = 500 ft
- Moving inward from D, each line increases by 100 ft.

Let’s label the lines going inward from 500:

Line through D: 500
Next line inward (through C): 600
Next: 700
Next: 800
Next: 900
Next: 1000
Innermost labeled: 1100

Now locate each point:

- Point D: on 500-ft line → 500 ft
- Point C: on the next line inward from D → that’s 600 ft → 600 ft
- Point B: Let’s see — it’s on a line that is 3 lines inward from the 800? Wait, better to count from center or from outside.

Actually, from the 1100 line outward:

Center: 1100
Next out: 1000
Next: 900
Next: 800 ← this is where point B is!
Yes — point B is on the 800-ft contour line.

Confirming: From 500 (D) → 600 (C) → 700 → 800 (B) → 900 → 1000 → 1100. That’s consistent.

- Point A: It’s on the same line as... wait, looking at the map, point A is on the line just outside the 800 line? Or inside?

Wait — let’s trace from point B (800) outward toward A.

From B (800), the next line outward is 700, then 600, then 500.

But point A is on a line that is *between* 700 and 600? No — actually, looking again:

The line that goes through point A — if we follow it around, it connects to the line that is one step outward from point B.

Point B is on 800.

Moving outward from B: next line is 700, then 600, then 500.

Point A is on the 700-ft line? Let me check the path.

Actually, draw an imaginary line from A to B — it crosses several contours.

But easier: Look at which contour line point A lies on.

From the bottom right: point A is on a contour line. If we go left from A, we hit the line that also runs near the bottom-left corner — that’s the 500 line? No, 500 is more to the left.

Wait — perhaps I should count from the 500 line upward.

Start at 500 (point D). Next ring inward: 600 (point C). Next: 700. Next: 800 (point B). Next: 900. Next: 1000. Center: 1100.

Now, where is point A?

Looking at the map, point A is located on the contour line that is *one ring outward from point B*. Since point B is on 800, the next ring outward is 700.

Is point A on the 700 line? Yes — because if you follow the line from A, it curves up and would be between the 600 and 800 lines — specifically, it's the 700 line.

Confirm: From 500 (D) → 600 (C) → 700 → 800 (B) → etc.

Point A is on the 700-ft contour line.

Wait — but let’s double-check with the line from A to B.

The question asks for elevation at “the point on line A to B” — probably meaning the midpoint or something? But first, let’s get individual points.

Actually, re-examining the map layout:

Points:

- D: on 500
- C: on next inward → 600
- Then next inward: 700 — no point labeled here
- Then 800 — point B
- Then 900, 1000, 1100

Where is point A? In the lower right, on a contour line. If we trace that line, it goes across the bottom and connects to the left side — but not to 500. Actually, it seems to be the 700 line.

Alternatively, maybe point A is on the 600 line? Let’s think differently.

Another approach: The contour line passing through point A — if we move along it, does it pass near any other known point? Not directly.

But notice: from point A to point B, the line crosses multiple contours. Specifically, from A to B, you cross from A’s line, then another, then reach B’s line.

If B is on 800, and assuming standard spacing, and since A is farther out, likely A is on 700.

Moreover, in many such problems, point A is often placed on the 700 line when B is on 800 and D on 500.

I think it’s safe to say:

- Point A: 700 ft
- Point B: 800 ft
- Point C: 600 ft
- Point D: 500 ft

Wait — but let’s verify point C again.

Point C is on the second line inward from D (500). So:

D: 500
First inward: 600 → that’s point C? Yes, the dot for C is on that line.

Then next inward: 700 — no point
Then 800 — point B
Then 900, 1000, 1100

Point A: in the southeast, on a line that — if traced — appears to be the 700 line. Because from the 500 line, going clockwise: after 500 comes 600 (with C), then 700 (no label), then 800 (B), then continuing, the line that goes to point A — yes, it should be 700.

Actually, wait — looking at the position: point A is almost aligned radially with point B, but further out. And between A and B, there is one contour line crossed? Or two?

Perhaps I made a mistake.

Alternative method: Use the fact that the highest point is 1100, and work outward.

Label all lines from center outward:

Center: 1100
Ring 1 out: 1000
Ring 2 out: 900
Ring 3 out: 800 → point B is here
Ring 4 out: 700
Ring 5 out: 600 → point C is here
Ring 6 out: 500 → point D is here

Now, where is point A? It is on ring 4 out? Or ring 5?

In the diagram, point A is located on the same "ring" as... let's see its angular position.

Actually, visually, point A is on the contour line that is between the 600 and 800 lines — specifically, it's on the 700 line.

Yes, because if you start from D (500), go to C (600), then the next unlabeled line is 700, and point A is on that 700 line.

Similarly, point B is on 800.

So:

- Point A: 700 ft
- Point B: 800 ft
- Point C: 600 ft
- Point D: 500 ft

This makes sense.

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Step 3: Answer question 2 — contour interval

As calculated earlier: from 500 to 1100 is 600 ft over 6 intervals → 100 ft per interval.

✔ Contour interval = 100 feet

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Step 4: Question 3 — elevation at the point on line A to B

This is ambiguous. What does “the point on line A to B” mean? Probably, it means the midpoint of the straight line drawn from A to B on the map.

On the map, there is a straight line drawn from A to B. Along that line, it crosses contour lines.

Specifically, from A (700) to B (800), the line goes directly from 700 to 800 — so it crosses only one contour line? Or does it stay within?

Actually, since A is on 700 and B is on 800, and they are on adjacent contour lines? No — 700 and 800 are adjacent if interval is 100.

Are A and B on adjacent contour lines?

A is on 700, B is on 800 — yes, adjacent.

The straight line from A to B will cross from the 700 line to the 800 line. But since they are on different lines, the line segment AB must cross the boundary between them — but actually, if A is on 700 and B on 800, and the lines are concentric, the straight line might not cross another contour; it goes from one to the next.

But the question says “the elevation at the point on line A to B” — singular. Perhaps it means the midpoint?

In many textbooks, when they say “the point on line A to B”, and there’s a straight line drawn, they often mean the midpoint of that line segment.

Assuming that, we need to find the elevation at the midpoint of AB.

Since A is at 700 ft and B is at 800 ft, and assuming the terrain slopes uniformly between them (which is a reasonable assumption for such problems unless stated otherwise), the midpoint would be halfway in elevation.

So, average of 700 and 800 = (700 + 800)/2 = 750 ft.

Moreover, since the contour interval is 100, 750 is exactly midway, which makes sense.

If the line crossed a contour, we’d note that, but here, since A and B are on consecutive contours, the midpoint should be at 750.

To confirm: the straight line from A to B likely does not cross any other contour line besides starting at 700 and ending at 800 — so yes, linear interpolation gives 750.

✔ So, elevation at midpoint of AB = 750 feet

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Final Answers:

1)
- Point A: 700
- Point B: 800
- Point C: 600
- Point D: 500

2) Contour interval: 100

3) Elevation at point on line A to B (midpoint): 750

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Final Answer:
1) Point A: 700, Point B: 800, Point C: 600, Point D: 500
2) 100
3) 750