Most of us have a hard time remembering our first years on Earth, and none of us remembers our earliest infancy. In geologic time, we might consider our 4.5-billion-year-old planet’s infancy to be its first 500 million years, and while scientists have a general idea of what the world was like way back then, they’re hazy on the details.
But a team of scientists used mathematical modelling to simulate conditions of early Earth and get some clarity about the formation and evolution of the Earth’s earliest continents.
Their study indicated that in the first 500 million years of Earth’s history—between about 4.5 billion and 4 billion years ago— the continents were weak and prone to destruction. These first 500 million years are called the Hadean eon, which gives you an idea about their fiery and molten conditions.
Unsurprisingly, these earliest continents didn’t survive; in the extreme temperatures of early Earth, they melted apart and were recycled into the Earth’s interior. But after those first 500 million years, things started to change. The melting and reworking became less frequent, and new continents become more stable and stiffer, forming the core parts of the continents we see today. These core pieces are called cratons, and they’re the only places on Earth where we can find traces of rock from Earth’s first 500 million years, the oldest of which appear as merely tiny crystals.
Much of early Earth is still a mystery, but we can say for certain that the continents have been through a lot since their infancy.