Geologists would argue that the discovery is not surprising because of southern China's karst topography, Veni, who works for a sister agency of the organization that explored the Chinese sinkhole, told Live Science's Stephanie Pappas. Karst is a "type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features," per the National Park Service. Common rock types in karst landscapes are limestone, marble and gypsum. Karst forms when rainwater picks up carbon dioxide as it falls through the atmosphere, creating H2CO3, carbonic acid. The lightly acidic water seeps through the ground, moving through fractures and openings in the rock. The water dissolves calcite, a mineral in limestone, marble and dolostone, creating the characteristic sinkholes, caves and streamways.