<Tr> <Td_colspan="2"> The geological eons and eras view discuss edit - 4500---- - 4000---- - 3500---- - 3000---- - 2500---- - 2000---- - 1500---- - 1000---- - 500---- 0--Hadean Archean Protero - zoic Phanero - zoic Eo Paleo Meso Neo Paleo Meso Neo Paleo Meso Ceno Scale: millions of years </Td> </Tr> <P> The Hadean (/ ˈheɪdiən /) is a geologic eon of the Earth predating the Archean . It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago . The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest - known rocks on Earth . W. Brian Harland later coined an almost synonymous term: the "Priscoan period". Other, older texts simply refer to the eon as the Pre-Archean . </P> <P> "Hadean" (from Hades, the Greek god of the underworld) describes the hellish conditions then prevailing on Earth: the planet had just formed and was still very hot owing to its recent accretion, the abundance of short - lived radioactive elements, and frequent collisions with other Solar System bodies . </P> <P> Since few geological traces of this eon remain on Earth, there is no official subdivision . However, the Lunar geologic timescale embraces several major divisions relating to the Hadean, so these are sometimes used in an informal sense to refer to the same periods of time on Earth . </P>

During the hadean eon which of the following is thought to have occurred