The sinkhole is 630 feet (192 meters) deep, according to the Xinhua news agency, deep enough to just swallow St. Louis' Gateway Arch. A team of speleologists and spelunkers rappelled into the sinkhole on Friday (May 6), discovering that there are three cave entrances in the chasm, as well as ancient trees 131 feet (40 m) tall, stretching their branches toward the sunlight that filters through the sinkhole entrance. The discovery is no surprise, Veni told Live Science, because southern China is home to karst topography, a landscape prone to dramatic sinkholes and otherworldly caves. Karst landscapes are formed primarily...