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,
Collapse! the two. Collapse! Collapse! is a series of award-winning tile-matching puzzle video games by GameHouse, a software company in Seattle, Washington. In 2007, "Super Collapse! 3" became the first game to win the Game of the Year at the inaugural Zeebys. The series has been discontinued since 2015 due RealNetworks shutting down its internal games studio. In 2006, a spin-off series called Super Collapse Puzzle Gallery! was developed into 5 games. The classic "Collapse!" game is played on a board of twelve columns by fifteen rows. Randomly colored blocks fill the board, rising from below. By clicking on a group