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,
Tiny (Once Upon a Time) Anton concludes that all humans are liars and resumes his attacks. David offers to surrender himself if Anton will spare everyone else. When Anton leaps towards David, he crashes through the ground into a sinkhole just as the mushroom wears off, leaving him human-sized and clinging to a pipe. David leads the townspeople in rescuing a despondent Anton from the pit, restoring his faith in humans. Anton is welcomed by the townspeople. He reveals the beanstalk stems and is brought to fertile farmland where he could grow beans, making it possible to return to the Enchanted Forest. He warns that