I just saw this article in the New York Times- apparently there’s a Nature paper…. I’ll have to find it. Even though I know nothing about geology- it doesn’t matter one bit! Apparently by looking at the chemicals in some crystals in some really, really (like 4 billion year old) rocks- UCLA geologists have changed the prevalent views of early earth and shown that the way things were during the Hadean period were “completely inconsistent with this myth we made up,”.(quoting one of the authors)…
Here’s the upshot in the NYT article:
With the old views of the Hadean period, the origin of life on Earth posed a huge problem. The earliest, and still debated, evidence for life lies within rocks in Greenland dated at 3.83 billion years. The rocks show a shift in the relative amounts of carbon-12, the usual form of carbon, and carbon-13, a less common but stable form of carbon. That shift was attributed to the presence of microorganisms, which would tend to concentrate the lighter carbon.
What was surprising, perhaps unbelievable, in the old views was that life started immediately at the end of the Late Heavy Bombardment, seemingly showing up the instant that it was possible.
In the new view of the early Earth, life could have emerged hundreds of millions of years earlier. “This means the door is open for a long, slow chemical evolution,” Dr. Mojzsis said. “The stage was set for life probably 4.4 billion years ago, but I don’t know if the actors were present.”
The revolution in early Earth studies comes largely from rocks in western Australia. The rocks are three billion years old, but they contain zircons that are older. Zircons, made primarily of the elements zirconium, oxygen and silicon, are extremely hard and durable and can survive conditions that erode, melt or otherwise transform the rock around them.
The emphasis is mine, and that is SO cool.