It seems that the further technology stretches toward the future, the more artifacts that humankind dredges from the past. In 2021, scientists confirmed that a crescent-shaped ridge in northeast China’s Heilongjiang Province marked the edge of a meteorite crater. Called the Yilan Crater, it took its name from a neighboring city.
Spanning 1.85 kilometres across and 319 metres deep, it formed some 50,000 years ago. This makes Yilan is the largest known impact crater on Earth under 100,000 years old. The scientific journal Meteoritics & Planetary Science published details of the discovery in its July 2021 issue.
Yilan Crater significance
By crater standards, Yilan is very young. Notably, it’s only the second crater known to China. The other, the Xinyuan Crater, is just slightly smaller (1.8km) but is thought to be significantly older, though it’s never been carbon dated.
The next largest crater from the same period as Yilan is the famous Barringer Crater in Arizona. Estimates indicate that an impact created the 1.2km crater about 49,000 to 50,000 years ago.
Two-thirds of the Yilan Crater’s ridgeline remains intact, which gives it a crescent-like appearance. Its rim rises 150m above the forest floor.
More than 100m of sediment and swampy, overgrown terrain covers the Yilan Crater’s basin. That organic layer overlays a dense, deep bedrock layer of granite. Inside the metamorphic rock, researchers found evidence of a super-heated impact.
The vegetation-covered rim of the Yilan Crater. Photo: Meteoritics & Planetary Science
Yilan impact evidence
People first settled around the crater, which they called Quanshan, or “circular mountain ridge”, centuries ago. But only in recent years did researchers begin to suspect that it was the site of a major extraterrestrial collision.
The team that published the 2021 article confirmed its suspicions by analyzing a core sample from the crater’s centre. It yielded ancient lake sediments, shattered granite, glass, and previously melted mineral deposits. Altogether, the findings constituted geological evidence of a high-impact origin.
To carbon-date the crater, experts sampled organic material and soot. The most precise estimates indicate that the Yilan Crater formed 47,000 to 53,000 years ago. If that date range is correct, it’s distinctly possible that ancient human inhabitants of Asia bore witness to the impact.
The roster of confirmed extraterrestrial impact craters on Earth includes around 190 sites. It’s a near certainty that many more craters exist, obscured beneath the cover of ice caps, buried deep within the sea, or worn away by the elements.
