What is a sinkhole?

A sinkhole is a depression in the ground that has no natural external surface drainage. Basically, this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface.

Sinkholes are most common in what geologists call, “karst terrain.” These are regions where the types of rock below the land surface can naturally be dissolved by groundwater circulating through them. Soluble rocks include salt beds and domes, gypsum, and limestone and other carbonate rock. Florida, for instance, is an area largely underlain by limestone and is highly susceptible to sinkholes.

When water from rainfall moves down through the soil, these types of rock begin to dissolve. This creates underground spaces and caverns.

Sinkholes are dramatic because the land usually stays intact for a period of time until the underground spaces just get too big. If there is not enough support for the land above the spaces, then a sudden collapse of the land surface can occur.

Find more information about sinkholes at the USGS Water Science School.

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Why are there no entries for caves or military installations in the Geographic Names Information System Database?

Entries for these categories are in the database, but are not available at the public Web site. In response to the 1988 National Cave Management Resources Act, an Interior Department Regulation (43 CFR Subtitle A, Part 37) forbids employees from releasing information regarding the location of a cave classified as significant on Federal lands. The...

What is the difference between a sinkhole and a pothole?

A sinkhole is a closed natural depression in the ground surface caused by removal of material below the ground and either collapse or gradual subsidence of the surface into the resulting void. A pothole is usually a fairly small feature caused by failure of paving materials, usually associated with roads, parking lots, and airports. In the colder...

What is the largest sinkhole in the United States?

There are some very large, ancient, ‘inactive’ sinkholes in some areas of the U.S. that are thousands of years old. Alabama claims to have the largest recent collapse sinkhole. It is called the “Golly Hole” and is located in Shelby County in the central part of the state. It collapsed suddenly in 1972. The sinkhole is about 325 feet long, 300 feet...

What is the difference between a sinkhole and land subsidence?

Sinkholes are just one of many forms of ground collapse, or subsidence. Land subsidence is a gradual settling or sudden sinking of the Earth’s surface owing to subsurface movement of earth materials. The principal causes of land subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural...

How many sinkholes open up in a year?

There is no database of sinkhole collapses for the United States, so these data are unavailable. Some individual state geologic surveys track reported collapses within their state. Many sinkhole collapses are not reported to authorities or news organizations, and many occur in rural areas where they are unobserved.

How much does sinkhole damage cost each year in the United States?

Sinkhole damages over the last 15 years cost on average at least $300 million per year. Since there is no national tracking of sinkhole damage costs, this estimate is probably much lower than the actual cost.
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Date published: July 25, 2016

EarthWord–Karst

Although it sounds like a Batman punch, this EarthWord is closer to the Bat than you’d think...

Filter Total Items: 24
Map of U.S. showing karst areas, which are prone to land subsidence and sinkholes.
March 20, 2017

Karst landscapes are more prone to have land subsidence and sinkholes.

Map of U.S. showing karst areas, which are prone to land subsidence and sinkholes.

The sudden and sometimes catastrophic subsidence associated with localized collapse of subsurface cavities (sinkholes) is detailed in two case studies. This type of sub-sidence is commonly triggered by ground-water-level declines caused by pumping and by enhanced

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October 25, 2016

Karst, Critters, and Climate Change

This webinar was conducted as part of the Climate Change Science and Management Webinar Series, co-hosted by the USGS National Climate Change and Wildlife Science Center and the FWS National Conservation Training Center. Webinar Description: One-half of North American imperiled species live in subterranean habitats, which largely are associated with karst (a type of

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Shenandoah sinkholes and karst geology maps
June 30, 2015

Shenandoah sinkholes and karst geology

Shenandoah sinkholes and karst geology

USGS
April 3, 2011

An Unseen World Beneath Our Feet - Caves, Sinkholes and Springs

Randall Orndorff, Director of the Eastern Geology and Paleoclimate Science Center, discusses how Karst affects daily life. Beneath a quarter of the United States are rock types that can dissolve to form caves, sinkholes and other features. Nearly every state has rock layers of limestone, gypsum, and other soluble rocks we call ‘karst’. Karst is important for many reasons.

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Photo collage of karst features in Buffalo National River
December 31, 2010

Karst features, Buffalo National River

Examples of karst features within the Buffalo National River Park. Karst is a type of topography that is formed over limestone, dolomite, or gypsum by dissolving or solution, and that is characterized by closed depressions or sinkholes, caves, and underground drainage (American Geological Institute Dictionary of Geologic Terms).

Image: Sinkholes in West-central Florida, Freeze Event of 2010
January 1, 2010

Sinkholes in West-central Florida, Freeze Event of 2010

More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and sections of cultivated areas.

Image: Sinkholes in West-central Florida, Freeze Event of 2010
January 1, 2010

Sinkholes in West-central Florida, Freeze Event of 2010

Sinkholes affect roadway safety and require constant maintenance and monitoring. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and sections of

...
Image: Sinkholes in West-central Florida, Freeze Event of 2010
January 1, 2010

Sinkholes in West-central Florida, Freeze Event of 2010

The entire root perimeter of this tree collapsed in response to subsidence activity. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and

...
Image: Sinkholes in West-central Florida, Freeze Event of 2010
January 1, 2010

Sinkholes in West-central Florida, Freeze Event of 2010

More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and sections of cultivated areas.

Image: Sinkhole Activity Damages Home.
January 1, 2010

Sinkhole Activity Damages Home.

Cracking along exterior walls is a sign of subsidence activity. Such severe structural damage from sinkholes can destroy homes and other structures. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the

...
Image: Sinkholes in West-central Florida, Freeze Event of 2010
January 1, 2010

Sinkholes in West-central Florida, Freeze Event of 2010

More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and sections of cultivated areas.

USGS
July 2, 2008

What are sinkholes?

Listen to hear the answer.