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Asteroids Kept Earth Molten, Blocking Continents
30 Jun
Summary
- Early Earth's crust remained too hot and unstable for continents.
- Repeated asteroid impacts reheated the planet's mantle significantly.
- Stable continental crust formation began around 3.9 billion years ago.
Four billion years ago, Earth's landscape was radically different from today's familiar continents and oceans. Instead, it endured an extended period of relentless asteroid strikes.
A recent study indicates these impacts were so powerful they prevented the formation of stable continents. The bombardment heated Earth's mantle, maintaining a molten crust too unstable for landmasses to solidify.
Scientists utilized computer simulations to analyze the cumulative energy from multiple asteroid impacts. This process reheated the mantle, causing significant melting and recycling of the crust over tens of millions of years.
Evidence from the Moon supports these findings, as its surface retains more traces of early asteroid collisions. The intense impact-heating effect appears to have diminished around 3.9 billion years ago, a timeframe that aligns with Earth's subsequent development of stable continental crusts.
This research may also explain the scarcity of rocks from Earth's earliest Hadean Eon. Such primitive rocks would likely have been destroyed by the combined heat from impacts and Earth's internal processes.
