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,
Wall Street and the Financial Crisis: Anatomy of a Financial Collapse Wall Street and the Financial Crisis: Anatomy of a Financial Collapse Wall Street and the Financial Crisis: Anatomy of a Financial Collapse is a report on the financial crisis of 2007–2008 issued on April 13, 2011 by the United States Senate Permanent Subcommittee on Investigations. The 639-page report was issued under the chairmanship of Senators Carl Levin and Tom Coburn, and is colloquially known as the Levin-Coburn Report. After conducting "over 150 interviews and depositions, consulting with dozens of government, academic, and private sector experts" found that "the crisis was not a natural disaster, but the result of high risk,