Sinkhole urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole. Sinkholes tend to occur in karst landscapes. Karst
Dream Caused by the Flight of a Bee Around a Pomegranate a Second Before Awakening them is Dalí's first use of an elephant with long flamingo legs, found in his later compositions such as "The Temptation of St. Anthony". The elephant carries on its back an obelisk, inspired by Bernini’s "Elephant and Obelisk" in Rome's Piazza Santa Maria sopra Minerva. The bayonet, as a symbol of the stinging bee, may represent the woman's abrupt awakening from her otherwise peaceful dream. This is an example of Sigmund Freud's influence on surrealist art and Dalí's attempts to explore the world of dreams in a dreamscape. The elephant is a distorted version of the Piazza della Minerva sculpture