Sinkholes are believed to be hollow at the bottom but recently Chinese scientists have discovered one with a full-scale flora inside it. "The UNESCO Global Geopark is primarily sedimentary with more than 60% of 3000m thick Devonian to Permian carbonate rocks," according to UNESCO's website. "It forms an 'S'-shaped structure and a rhombus configuration in the karst areas of Leye and Fengshan counties respectively, which controlled two large subterranean rivers' development, the Bailang and Poyue."