Sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other. Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or in other soluble rocks, such as gypsum, that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains. As the rock dissolves,
2010 Guatemala City sinkhole 2010 Guatemala City sinkhole The 2010 Guatemala City sinkhole was a disaster in which an area approximately across and deep collapsed in Guatemala City's Zona 2, swallowing a three-story factory. The sinkhole occurred for a combination of reasons, including Tropical Storm Agatha, the Pacaya Volcano eruption, and leakage from sewer pipes. Overall, the risk of sinkholes occurring in Guatemala City is high and unpredictable. One recent, similar sinkhole had collapsed in 2007, forming a pit 100 metres deep. The 2007 Guatemala City sinkhole was formed by fluid from a sewer eroding uncemented volcanic ash, limestone, and other pyroclastic deposits underlying