Acasta Gneiss
Gneisses on the Acasta River in Canada's Northwest Territories that hold the oldest known evolved crust on Earth, with zircons up to about 4.03 billion years old. They record over a billion years of magmatism, from the Hadean into the Archean.
Dated events and their evidence
- about 4,020,000,000 years ago mainstream
the Idiwhaa tonalitic gneiss crystallises about 4.02 billion years ago, the oldest dated unit of the Acasta Gneiss Complex source - 1985 CE mainstream
J. E. King informally names the Acasta gneiss complex after the Acasta River, during Geological Survey of Canada mapping source
Where
65.1666° N, 115.5820° W
The point is the Wikidata position of the Acasta Gneiss, along the Acasta River east of Great Bear Lake, about 300 km north of Yellowknife.
Sources
- https://en.wikipedia.org/wiki/Acasta_Gneiss
- https://doi.org/10.1111/jmg.12759
- https://doi.org/10.1007/s00410-025-02254-0
- https://doi.org/10.1126/sciadv.abc9959
- https://ozgeology.com/blogs/news/the-oldest-rocks-on-earth-what-they-reveal-about-early-planetary-history
Each event carries Aion's own evidence grade (mainstream, disputed or speculative). This page repeats what the globe shows for this place.