

It's buried beneath a lava bed in Laos.

A meteor strikes Earth. Clouds cover an ocean area of the planet. Planetary material is ejected back into space.
Marc Ward/Stocktrek ImagesGetty Images
  • Scientists have unearthed evidence of a massive impact crater in Laos that for nearly 800,000 years has sat hidden beneath 1,ooo feet of lava, the New York Times reports.
  • The crater is approximately 11 miles long, 8 miles wide, and more than 300 feet deep.
  • Impact craters this large provide vital clues about the major geologic events that have shaped life on Earth.

    Roughly 800,000 years ago, an asteroid smashed into Earth's surface. The asteroid carved a hole in the Earth that was 11 miles long, 8 miles wide, and nearly 300 feet deep.

    Scientists found ample evidence of the collision—the blast lobbed tektites, a type of extraterrestrial rock, across 10 percent of the planet. Rock samples were found in Antarctica, parts of Southeast Asia, and on islands in the Pacific.

    But no evidence of a crater was ever uncovered ... until now.

    A team of geologists, led by Kerry Sieh of the Earth Observatory of Singapore, claims to have discovered evidence of such a crater in Laos. The scientists recently reported their findings in the Proceedings of the National Academy of the Sciences.

    But how had the planet managed to hide such a massive gash? Evidence of earlier impacts, millions or billions of years old, are often eroded over time or swallowed by sinking tectonic plates. But the 800,000-year-old impact should have left a visible mark.

    Here's the thing: It did, but that mark was just tucked beneath 1,000 feet of lava that poured out of a Laotian volcano in the years since, the New York Times reports. The evidence that a crater lies beneath all that lava is mounting.

    In addition to finding scattered tektites, Sieh and his colleagues have studied nearby road cuts, which often chop through large chunks of geologic time, and have found overturned boulders that have grains of shocked quartz, a tell-tale clue that there was an explosive impact.

    Researchers studying the road cut believe the boulders pummeled the ground at a speed of about 450 meters per second—so, really, really fast. When an asteroid slams into Earth, the rapid rise in temperature and pressure alters grains, leaving little laminations in the crystals that are sometimes visible to the naked eye.

    Another compelling piece of evidence that something had happened in the area were the curious gravitational signals that the scientists found. Impact craters can have a weaker gravitational fill due to the type of loosely packed material that falls back inside them after the initial collision. Gravitational measurements are how researchers were able to estimate the crater's dimensions.

    It wouldn't be the first example of an impact crater that's been hidden from view. In 2018, scientists discovered an impact crater buried beneath a glacier in Greenland, which they say was created 11,700 years ago. In 1978, scientists found the Chicxulub Crater, which they later proved to have ended the era of the dinosaurs.

    But some researchers have cautioned that they need to do more work before claiming without question that a crater lies beneath the Laotian lava flows. Drilling into the rock could provide helpful clues, too. Understanding when and where these asteroid impacts occur sharpens our understanding of how life on this planet has overcome obstacles in the past.

    Advertisement - Continue Reading Below
    More From Earth