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=== Sinkholes === | === Sinkholes === | ||
[[File:Thor's Well (37588682016).jpg|250px|border|right|thumb|Thor's Well: a sinkhole on the coast of Cape Perpetua, Oregon]] | |||
[[File:December_Giant_sinkhole_collapse_USGS_1972.jpg|right|250px|thumb|More than three acres of forest suddenly disappeared into the "Golly Hole" or "December Giant" sinkhole in Montevallo, Alabama, USA. (wiki)]] | |||
* sinkholes are holes or caves in the ground caused by erosion or a collapse of a lower, below-ground surface, usually because of water drainage | * sinkholes are holes or caves in the ground caused by erosion or a collapse of a lower, below-ground surface, usually because of water drainage | ||
* sinkholes may also be caused by a drainage of water, such as a water table decline | * sinkholes may also be caused by a drainage of water, such as a water table decline | ||
* sinkholes are most common where limestone, sandstone, salt beds, or gypsum are prevalent | * sinkholes are most common where limestone, sandstone, salt beds, or gypsum are prevalent | ||
* Thor's Well | * Thor's Well | ||
** a sinkhole on the coast of Cape Perpetua, Oregon, that drains at high tides | ** a sinkhole on the coast of Cape Perpetua, Oregon, that drains at high tides | ||
* Golly Hole in Shelby County is considered the largest sinkhole in the US. | * Golly Hole in Shelby County is considered the largest sinkhole in the US. | ||
** also known as the "December Giant," it formed in 1972 after water drainage at a nearby quarry, | ** also known as the "December Giant," it formed in 1972 after water drainage at a nearby quarry, | ||
** it is 325 ft long, 300 ft wide, and 120 ft deep | ** it is 325 ft long, 300 ft wide, and 120 ft deep | ||
* source: [[https://www.usgs.gov/faqs/what-largest-sinkhole-united-states?qt-news_science_products=0#qt-news_science_products What is the largest sinkhole in the United States? (usgs.gov)]] | * source: [[https://www.usgs.gov/faqs/what-largest-sinkhole-united-states?qt-news_science_products=0#qt-news_science_products What is the largest sinkhole in the United States? (usgs.gov)]] | ||
* See | * See also | ||
** [[https://www.usgs.gov/special-topic/water-science-school/science/sinkholes?qt-science_center_objects=0#qt-science_center_objects SinkHoles (USGS.gov)]] | |||
** [[https://en.wikipedia.org/wiki/Sinkhole Sinkhole (wiki)]] | ** [[https://en.wikipedia.org/wiki/Sinkhole Sinkhole (wiki)]] | ||