Aeon | Archean

: The end of the Archean (3.0–2.5 Ga) marked the global initiation of "modern-style" subduction-collision cycles as the planet cooled. Atmosphere and Climate

: Rocks known as TTGs (Tonalite-Trondhjemite-Granodiorite) dominate the Archean record, reflecting unique magmatic processes driven by the Earth's significantly higher internal heat. archean aeon

The (also spelled Archaean ) is a major division of geologic time extending from 4.0 to 2.5 billion years ago (Ga) . It follows the Hadean and precedes the Proterozoic aeon. The name is derived from the Greek word for "beginning," as it represents the earliest substantial part of the Earth's rock record. Geological and Tectonic Environment : The end of the Archean (3