An asteroid at least twice the size of the K-T dino killer struck the Earth billions of years ago and it left a mark. Because weathering and plate tectonics, or some early version, were well enough underway by then, almost all of surface material on Earth exposed at that time has long been eroded into dust, or subducted and recycled into the mantle, and lost completely. But in this case, the impact was large enough that some of the widespread ejecta managed to leave a surviving record:
The evidence of the ancient mega-collision was unearthed in a rock formation known as the Marble Bar, in northwestern Australia. The sediments are roughly 3.5 billion years old and create a fuzzy snapshot of what early Earth was like during the Archean eon, roughly 4 billion to 2.8 billion years ago.
The evidence of the impact was unearthed in a portion of the sediments that originated on the ocean floor. These ocean sediments were then preserved between two layers of volcanic sediments that could be dated with a high degree of precision, allowing the scientists to determine exactly when the impact occurred. While glass spherules are often a sign of an impact, the team found that the levels of platinum, chromium and nickel found in the spherules were very similar to those found inside asteroids.
- For millennia, we have relegated half our population to second class status. Just in science alone, how many Einsteins or Newtons have we lost to this indefensible practice? Well, one visionary video game developer, creators of Cards Against Humanity, is leading the charge to change that, they’ve awarded a scholarship to Sona Dadhania, at the University of Pennsylvania:
But they’re not done here! The pack has so far raised more than $880,000—yes, you read that correctly—to help women get a STEM degree. That means there’s plenty left over for more scholarships, and applications for Round 2 will be opened this fall. Stay tuned.
President Barack Obama declared science “is fun” Thursday as he recognized 17 leading scientists and innovators for work helping put “countless revolutionary discoveries within our reach.”