Cave explorers stumbled upon a prehistoric forest at the bottom of a giant sinkhole in South China earlier this month. Sinkholes such as these are also known in Chinese as Tiankeng, or "Heavenly pit."
At 630 feet deep, the sinkhole would hide the Washington Monument and then some. The bottom of the pit holds an ancient forest spanning nearly three football fields in length, with trees towering over 100 feet high. And according to the Chinese government, it is one of 30 enormous sinkholes in the county.
