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Acasta Gneiss Canada Large [1948] Out-of-Stock

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Why is Acasta gneiss so important? It gives us a very rare opportunity to learn so many things about Deep Time. To hold in our hands something from just about half a billion years younger than the age of the Earth and almost one-third of the age of the universe is tremendously powerful. Geologic time reference rocks like this one helps us to better conceptualize the division in Earth's earliest geologic history, the Cryptic era, Hadean age.

Acasta gneiss is the oldest relic of bedrock terrain on our planet. It has survived Earth's earliest history to give us a snapshot into "Deep Time." We don't often have an opportunity in geology to compare the age of the Earth to the age of the Universe. Acasta gneiss is about 4 billion years old and the age of the universe is estimated to be about 13.8 billion years old. The age of the Earth is about 4.5 billion and we are...but a smidgeon in time. But we do have an opportunity to gain a toe-hold on what geologic time really means.

Acasta Gneiss is located in the remote Slave Lake province, Northwest Territories, Canada. This province is one of the oldest known zircon-bearing evolved crustal outcrops on Earth, forming during the earliest time of our planet's history, the Hadean eon. The name is taken from the nearest location, the Acasta River, which is east of Great Slave Lake - some good distance north of Yellowknife. The rock exposed at this outcrop formed about 4.03 Ga. It is an age based on radiometric dating of zircon crystals. During the earliest part of the Hadean eon the Earth’s surface was incredibly unstable. Deep convection currents in the Earth's mantle brought fiery, molten rocks to the surface and caused cooling rocks to descend into the magmatic seas. The heavier elements, like iron, descended to become the core and the lighter elements, such as silicon, became a part of the growing crust. Its unknown when the first outer crust of the planet fully formed, but it is thought that the existence of grains of zircon dated to about 4.4 billion years ago (Jack Hills Zircon) indicated the presence of liquid water and stable continents. The surface temperatures then were probably less than 212 °F.

Few rocks and minerals remain from the Hadean eon because nearly all of this original crust has been subducted, either due to tectonic plate movements and other geological processes. The oldest rocks known on Earth so far are the faux amphibolite volcanic deposits of the Nuvvuagittuq greenstone belt in Quebec, Canada which are estimated to be about 4.28 billion years old. The Jack Hills zircon rocks, in Australia, contain the oldest mineral grains so far found on Earth. They provide compelling evidence that have led scientists to believe that the atmosphere and oceans most likely formed before 4.4 billion years ago.

Specimen size: 72mm L X 60mm W X 32mm D; Weight: 108.2

Ships with a Certificate of Authenticity, tag, tag stand and information about Acasta gneiss. Display stand and photo cube not included.

This Acasta gneiss was obtained in a materials trade with a scientific institution.

This specimen is very budget friendly and would make an important contribution to a scientific collection.


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