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Answer: A sinkhole is a closed depression in the ground that forms when rock below is dissolved or removed, and the surface either sags slowly or collapses into the void. They are most common over limestone, other carbonate rock and salt beds that groundwater can dissolve.

How they form

1. Rainwater soaking through soil slowly dissolves soluble rock.
2. Spaces and caverns grow underground.
3. The surface often stays intact until the spaces get too big; then it can collapse suddenly.

Most sinkholes form slowly with little visible change.

Size and drainage

Sinkholes range from a few feet to hundreds of acres across and from under 1 to more than 100 feet deep. Water that falls inside usually drains underground rather than running off.

Where in the U.S.

The most damage tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania. In January 2010, heavy groundwater pumping to protect crops from a freeze helped trigger more than 110 sinkholes near Dover, Florida.

Not a pothole

A pothole is a small failure in pavement, not a geologic sinkhole. There is no national database of sinkhole collapses.

Claims

• id: C1 claim: Sinkholes are common where rock below can be dissolved by groundwater. source: S1 evidence: "Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt"
• id: C2 claim: More than 110 sinkholes formed near Dover, Florida in January 2010. source: S1 evidence: "More than 110 sinkholes formed in the Dover area of Florida during a freeze event"
• id: C3 claim: The most damage occurs in Florida, Texas, Alabama and other states. source: S1 evidence: "The most damage from sinkholes tends to occur in Florida, Texas, Alabama, Missouri"
• id: C4 claim: A sinkhole is a closed natural depression in the ground surface. source: S2 evidence: "A sinkhole is a closed natural depression in the ground surface"
• id: C5 claim: There is no database of sinkhole collapses for the United States. source: S2 evidence: "There is no database of sinkhole collapses for the United States"

Sources

• [S1] Sinkholes. USGS. https://www.usgs.gov/special-topics/water-science-school/science/sinkholes . License: US government work, public domain. Accessed 2026-11-04.
• [S2] What is a sinkhole?. USGS. https://www.usgs.gov/faqs/what-a-sinkhole . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_rnbtjm7z,
  author = {{iinventedlight}},
  title = {{Sinkholes}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/sinkholes/},
  note = {Permanent ID iil:note:rnbtjm7z. License: CC-BY-4.0.},
}

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