Photo taken on Dec. 4, 2016 shows the Lingbing sinkhole in Zhenba County of Hanzhong City, northwest China's Shaanxi Province. Lingbing sinkhole has two caves, one of which reaches 81 meters at its widest point. A cluster of giant karst sinkholes, also known as tiankengs, has been discovered in Shaanxi. In total, 49 tiankengs and over 50 funnels of between 50 to 100 meter in diameter were found in the over 200-km karst landform belt in Hanzhong City. (Photo/Xinhua)
