Description

The Jack Hills zircons are the oldest terrestrial materials found so far. These detrital grains from a quartzite / metaconglomerate unit in western Australia clock in at between 4.0-4.4 Ga with a single grain dating at 4.4 Ga in age. The Jack Hills are located in the Narryer Gneiss Terrane of the Yilgarn Craton, Western Australia, and comprise an 80 kilometres (50 mi) long northeast-trending belt of folded and metamorphosed supracrustal rocks.Sedimentary siliciclastic rocks, interpreted as alluvial fan-delta deposits, are the major lithology. A small fragment of a mineral called zircon extracted from a remote rock outcrop in Australia confirms that the Earth's crust first formed at least 4.4 billion years ago (Hadean eon).