4500 – 4400 million years ago

Year two

Crust, zircon and oceans

The oldest known thing to have formed on Earth, zircon, formed along with solid crust and oceans.

The young Earth was covered in craters, rocks and dust, and there would have been lots of volcanoes. From the volcanoes came huge amounts of steam, which condensed onto the cooler crust to form the oceans. This was also a time when there was a great bombardment of water-laden meteorites that contributed to the formation of the Earth's oceans.

The oldest surviving things that are known to have formed on the Earth are crystals of a mineral called zircon. The composition of these crystals suggests that not only had a solid crust formed, but seas had also developed by the time Earth was only two years old (4400 million years ago).

The earliest Earth was molten, but by about 4400 million years ago the crust had solidified and water began to condense on its surface. At first, these water bodies were small and shallow, but sometime after about 3800 million years ago, the first oceans began to develop.

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