Zhejiang Changxing Golden Nail Geological Museum Royalty-Free Stock Image

The “golden nails” are collectively referred to as global boundary layer profiles and points, and are the global standard between chronostratigraphic systems and systems. The Changxing Coal Mountain D section is the largest fault boundary line type in the history of earth development. In 1985, Zhang Kexin, a professor at China University of Geosciences, discovered the tooth-shaped fossil at the bottom of the D section 27C, thus establishing the international status of the profile.