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,
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