Zircon Crystal is 'oldest scrap of Earth crust'

A tiny 4.4-billion-year-old crystal has been confirmed as the oldest fragment of Earth's crust.

The zircon was found in sandstone in the Jack Hills region of Western Australia.

Scientists dated the crystal by studying its uranium and lead atoms. The former decays into the latter very slowly over time and can be used like a clock.

The finding has been reported in the journal Nature Geoscience.

Its implication is that Earth had formed a solid crust much sooner after its formation 4.6 billion years ago than was previously thought, and very quickly following the great collision with a Mars-sized body that is thought to have produced the Moon just a few tens of millions of years after that. Before this time, Earth would have been a seething ball of molten magma.

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LOST CONTINENT FOUND BY RADIOMATRIC DATING

A lost continent which sank millions of years ago has been found at the bottom of the Indian Ocean.

Named Mauritia by scientists, it is believed to have existed intact up to 85million years ago.

Part of this small microcontinent is still above water, and is now part of the Seychelles, a group of islands between Madagascar and India.

The discovery was made after sand from the beaches of Mauritius was analysed and found to be hundreds of millions of years older than expected.

The grains contained zircon minerals up to 1.9billion years old that may have formed part of the ancient land of Rodinia.

They were dragged 10km (6.2 miles) up to the surface after a volcanic eruption 9million years ago.

Zircon is something you typically find in a continental crust – they are very old in age.’

India drifted from Madagascar causing the microcontinent to break up and disappear into the sea. However, some of the land has survived.

‘At the moment, the Seychelles is a piece of granite, or continental crust, sitting practically in the middle of the Indian Ocean,’ Prof Torsvik, told the journal Nature Geoscience.

‘But once upon a time it was sitting north of Madagascar.

‘What we are saying is maybe this was much bigger. There are many of these continental fragments spread around in the ocean.’