The official reference point for the worst extinction in Earth's history, when 96% of species died 252 million years ago. The rock layers record how oceans turned anoxic and the atmosphere filled with volcanic gases. It took 10 million years for ecosystems to recover.
The Golden Spike
In a former quarry in Zhejiang province, an unassuming rock face holds the internationally recognized dividing line between two geologic eras. This is the Meishan Section, designated in 2001 as the Global Boundary Stratotype Section and Point (GSSP) for the Permian-Triassic boundary. A GSSP, or "Golden Spike," is a single, agreed-upon location that defines the start of a new geological age. The Meishan Section contains two such markers, also defining the base of the Changhsingian, the final stage of the Permian.
The Permian-Triassic boundary marks the "Great Dying," the most severe extinction event known. The rocks here document the end of the Paleozoic Era and the beginning of the Mesozoic Era. Before the extinction, the diverse tropical marine fauna in this area included over 330 species. The extinction event itself was geologically rapid, occurring over approximately 60,000 years. The specific boundary is located at the base of a limestone layer known as Bed 27c. Its definition rests on the first appearance of a tiny, eel-like creature's tooth-like fossil: the conodont Hindeodus parvus. This fossil is the primary global marker for the beginning of the Triassic period, 251.9 million years ago.
Reading the Catastrophe
The story of the extinction is written in the section's distinct layers of limestone, mudstone, and volcanic ash. The layers below the boundary, in the Changhsingian Formation, are full of fossils of brachiopods, corals, and other invertebrates. As the layers approach the boundary, this diversity collapses. Bed 25, a volcanic ash layer dated to 252.28 million years ago, signals the onset of the crisis. The layers show a sharp negative shift in carbon-13 isotopes, evidence of a massive disruption to the global carbon cycle.
Geochemical analysis reveals a cascade of environmental failures. The rocks show evidence of a rapid 10°C temperature rise, ocean acidification, and anoxia, a severe depletion of oxygen in the water. Increases in elements like mercury and nickel in the sediments provide a direct chemical fingerprint linking the extinction to immense volcanic activity. The disappearance of complex burrows made by seafloor animals, replaced by only simple, shallow trails, shows the collapse of benthic ecosystems.
A Volcanic Apocalypse
The trigger for the Great Dying was the Siberian Traps, a large igneous province in modern-day Russia. Eruptions there began about 300,000 years before the extinction and continued for roughly two million years. This event expelled a volume of lava large enough to cover the United States in a kilometer-deep layer of magma.
The eruptions released trillions of tons of carbon dioxide, methane, and sulfur dioxide into the atmosphere. This led to extreme global warming, which heated the oceans. Warmer water holds less dissolved oxygen, creating the anoxic conditions recorded in the Meishan rocks. The atmospheric upheaval and subsequent acid rain also devastated terrestrial ecosystems, leading to the extinction of 70% of land species. The evidence preserved at Meishan shows how this single, prolonged volcanic event pushed the entire planetary system past a tipping point from which it took millions of years to recover.
💡Fun Facts
The Permian-Triassic extinction is nicknamed "The Great Dying."
The first appearance of the conodont *Hindeodus parvus* in Bed 27c formally marks the beginning of the Triassic Period.
The event was so destructive to plant life that it created a "coal gap," a period of millions of years in the Early Triassic with no new coal deposits.
The Siberian Traps eruptions released enough magma to cover an area of about 7 million square kilometers.
The site is a protected National Geoheritage Reserve and primarily an active research location. Public access may be restricted; there are no set public visiting hours. The nearby Changxing Museum of Paleontology contains exhibits about the site.
Admission
N/A
Accessibility
The GSSP is located in a former quarry. The terrain is natural and can be uneven.