How can I recognize a hill or a depression in a contour diagram?

Start with the elevation information, not just the outline. Contour lines join places at equal elevation, so their labels—and the contour interval, if provided—help you compare heights. [S2] Look at nested loops and ask whether the labeled elevations rise or fall as you move toward the middle.

For an invented example, suppose the loops are labeled 100, 110, and 120 from outside to inside. The ground is higher toward the center, suggesting a hill. If the labels instead read 100, 90, and 80 inward, the ground drops toward the center, suggesting a low area. These are examples, not measurements from a real map.

Not reliably from a plain closed-loop pattern alone. A closed contour without elevation labels or another distinguishing cue may not show whether the land rises or falls inward. [S1] Check the diagram’s legend and look for additional markings before classifying it.

On US Topo maps, closed contours marked with inward-pointing hash marks indicate a depression; the hashes point toward the lower point. [S1] If the diagram has neither useful elevation information nor distinguishing marks, record the result as “uncertain from this diagram” rather than assuming the loops show a hill.

Use these invented examples. Read each sequence from the outer loop toward the center:

1. A: 200, 210, 220. The values increase inward, so the center is higher: this suggests a hill.
2. B: 200, 190, 180. The values decrease inward, so the center is lower: this suggests a low area.
3. C: Three closed loops, no labels, no contour interval, and no marks. The pattern alone does not establish whether the center is high or low.
4. D: A closed loop with inward-pointing hash marks on a US Topo map. Those marks indicate a depression. [S1]

The direction of change is the key in A and B. For C, the correct answer is that the information is insufficient—not a forced guess.

Use this sequence: find the closed contours, read any elevation labels from outside inward, and compare the numbers. Use the contour interval to help interpret the height changes when it is given. Check the legend and look for distinguishing marks, too. Do not treat the loop shape alone as proof that the middle is higher or lower. [S1] [S2]

A concise annotation could be: “The elevations [increase/decrease] toward the center, so the center is [higher/lower]. This suggests a [hill/low area].” If there are no elevation clues or distinguishing marks, write: “Cannot determine from the markings shown.”