What is the Hadean eon?
Q: What is the Hadean eon?
A: The Hadean eon is the geological eon before the Archaean. It began at Earth's formation about 4.6 billion years ago, and ended 4 billion years ago.
Q: Where does the name "Hadean" come from?
A: The name "Hadean" comes from Hades, Greek for "Underworld", due to the conditions on Earth at that time.
Q: Who first used the term "Hadean"?
A: The geologist Preston Cloud first used the term in 1972.
Q: What were conditions like on early Earth?
A: Meteorite bombardment, volcanism and high temperatures were very widespread on early Earth.
Q: Are there any sedimentary rocks from this eon?
A: No, there are no sedimentary rocks from the Hadean at all.
Q: What evidence supports a giant impact hypothesis for how our Moon was formed?
A: Evidence supporting a giant impact hypothesis includes similarity between Earth's crust and Moon's composition, low iron concentration in Moon's centre, and high angular momentum of Earth-Moon system.
Q: Why are there so few rocks from this era?
A: An explanation for lack of Hadean rocks (older than 3800 mya) is large amount of rocky and icy debris present in early Solar System which bombarded early Earth until approximately 3800 mya, preventing large crustal fragments from forming by shattering protocontinents.
