Cambrian–Ordovician Boundary Stratotype Section

Cambrian–Ordovician Boundary Stratotype Section

Cambrian–Ordovician Boundary Stratotype Section

The Cambrian–Ordovician Boundary Stratotype Section is located on the north side of National Highway 201 in Dayangcha Town, Jiangyuan District, and is one of only two such sections remaining in the world.

This section is situated on the southern edge of the North China ancient plate on the Eurasian Plate (late Cambrian), formed in an ancient ocean around 510 million years ago. It is one of the two international Cambrian–Ordovician boundary stratotype sections established by the International Commission on Stratigraphy in 1985, and is considered the better of the two. Compared to the other section in Newfoundland, Canada, this one exhibits greater continuity and completeness in the sedimentary rocks and paleontological sequences near the Cambrian–Ordovician boundary. The first appearance of floating graptolite layers occurs at a lower horizon, and the fossil assemblage is richer, making it the global reference point and comparative standard for the Cambrian–Ordovician boundary, as well as the marker for establishing the global geological time frame of the Cambrian–Ordovician period.

On July 24, 1986, the International Commission on Stratigraphy held a “Dayangcha Cambrian–Ordovician Boundary Field Investigation and Academic Symposium” here, attended by over 100 scholars and experts from 70 countries. By studying the paleomagnetism, paleolatitude, paleoclimate, paleogeography, paleogeology, and paleontology of this section, researchers can interpret the age of the strata, the formation, evolution, and changes of the Earth's crust in the Changbai Mountain area, as well as the history of the planet we inhabit. It also helps address many long-standing and critical issues in earth sciences and life sciences, offering significant scientific research value for tracing geological history.

The area surrounding this section is also a fossil site of plants and animals that holds great scientific value for understanding the evolution of the Earth and life. Through the study of stratigraphy—especially the rich fossil assemblages within these sedimentary strata, including trilobites, graptolites, conodonts, echinoderm eocrinoids, and brachiopods—this section provides an excellent window and crucial empirical evidence for the study of life’s evolution on Earth. The fossils found here offer detailed insights into the evolution of life forms from 510 million years ago, representing some of the oldest and most primitive records of life on our planet.