Introduction to the cliff carvings of the Northern Song Dynasty: The cliff carvings were carved on the hard basalt steep walls in the canyon in the second year of Xining in the Northern Song Dynasty (1069). The inscription is arranged in four vertical lines and reads: "Zhao Zhan, Cai Yanqing, and Lei Zhoufu traveled to Shuigu together on March 28, the second year of Xining." Each word is 8 centimeters and rectangular. Although it has been eroded by wind and water for 941 years, the handwriting is still clearly legible.