- The Archean Eon (IPA: /ɑːrˈkiːən/ ar-KEE-ən, also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth’s history, preceded by the Hadean Eon and followed by the Proterozoic. The Archean represents the time period from 4,031 to 2,500 Ma (millions of years ago). The Late Heavy Bombardment is hypothesized to overlap with the beginning of the Archean. The Huronian glaciation occurred at the end of the eon.
- Proterozoic (Wikipedia)
The Proterozoic (IPA: /ˌproʊtərəˈzoʊɪk, ˌprɒt-, -əroʊ-, -trə-, -troʊ-/ PROH-tər-ə-ZOH-ik, PROT-, -ər-oh-, -trə-, -troh-) is the third of the four geologic eons of Earth’s history, spanning the time interval from 2500 to 538.8 Mya, the longest eon of the Earth’s geologic time scale. It is preceded by the Archean and followed by the Phanerozoic, and is the most recent part of the Precambrian “supereon”.
- Hadean (Wikipedia)
The Hadean (IPA: /heɪˈdiːən, ˈheɪdiən/ hay-DEE-ən, HAY-dee-ən) is the first and oldest of the four known geologic eons of Earth’s history. The Hadean eon started with the planet’s formation about 4.54 Bya, now defined as (4567.30 ± 0.16) Mya set by the age of the oldest solid material in the Solar System found in some meteorites about 4.567 billion years old. The proposed interplanetary collision that created the Moon occurred early in this eon, and the Late Heavy Bombardment is hypothesized to have occurred at the end of the eon. The Hadean ended 4.031 billion years ago, and was succeeded by the Archean eon.