Chiang Khong Subdistrict is located on the west side of Sri Nan National Park, 24 kilometers away from the National Park Office, it is a earth pillar that looks strangely similar to "Phae Mueang Phi" in Phrae. Sao Din Na Noi caused by sedimentary land deposition and move up from the surface of soil. Millions of years have passed being eroded by water and rain, causing a strange shape as you can see. It is assumed that Sao Din Na Noi is about 30,000 -10,000 years old and used to be the bottom of the sea. In addition, stone bracelets and ancient axe were also discovered here. (Currently preserved at the Nan National Museum) Shows that this area may have been habitat of old Stone Age man.