By Sara E. Pratt, NASA Earth Observatory
February 28, 2022
In the image above, acquired by the Operational Land Imager (OLI) on Landsat 8 on October 8, 2021, the scalloped northern rim of Yilan crater is highlighted by fall foliage. The northern rim– which increases 150 meters (500 feet) above the crater flooring– is unspoiled, but the southern third of the crater rim is missing.
The asteroid that produced the crater struck relatively just recently in geologic time, the granite rocks it impacted were much older, having formed about 200 million years back in the Early Jurassic Period. To examine the impact structure, the research team drilled down 438 meters (1,440 feet) into the center of the crater, where they discovered hundreds of meters of ancient lake sediments and shattered granite.
The researchers continue to investigate the reason for the missing out on southern rim. The existence of lakebed sediments inside the crater suggests the rim was intact long enough for significant deposits to construct up on the lake bottom. Such deposits typically produce abundant, organic soil; some farm fields can be seen inside the southern part of the crater. The rest of the crater interior is covered with swamps and forest wetlands.
NASA Earth Observatory image by Lauren Dauphin, using Landsat information from the U.S. Geological Survey.
Despite Chinas large land area, just one impact crater– the reasonably little Xiuyan crater in Liaoning province– had been found there prior to 2020. The Yilan crater, somewhat larger than Xiuyan, covers about 1.85 kilometers (1.15 miles), making it the largest crater on Earth under 100,000 years old. The asteroid that produced the crater struck fairly just recently in geologic time, the granite rocks it impacted were much older, having actually formed about 200 million years earlier in the Early Jurassic Period. To investigate the impact structure, the research team drilled down 438 meters (1,440 feet) into the center of the crater, where they discovered hundreds of meters of ancient lake sediments and shattered granite.
October 8, 2021
The 50,000-year-old crater is relatively young, and only the second discovered in China.
Despite Chinas large acreage, only one impact crater– the reasonably small Xiuyan crater in Liaoning province– had been found there prior to 2020. Last year, a group of geologists found another crater northwest of Yilan in Heilongjiang Province. The crater was discovered in the greatly forested Lesser Xing a mountain range, where local residents knew it as “Quanshan,” or “circular mountain ridge.”
The Yilan crater, slightly bigger than Xiuyan, covers about 1.85 kilometers (1.15 miles), making it the largest crater on Earth under 100,000 years old. Carbon-14 dating of charcoal and organic lake sediments recommends the crater formed in between 46,000 and 53,000 years earlier. Meteor (or Barringer) Crater in Arizona is also approximately 50,000 years of ages, but its diameter is 1.2 kilometers (0.75 miles).
