Geology
The rock exposed in the outcrop is derived from a 4.2 billion year old granitoid; an age based on radiometric dating of zircon crystals at 4.2 Ga. The Acasta Gneiss is important in establishing the early history of the continental crust. It was formed in the Basin Groups unofficial period of the Hadean eon, which came before the Archean: see Timetable of the Precambrian.
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