query: When was the Hadean era?
passage: Hadean
The Hadean (/ˈheɪdiən/) is a geologic eon of the Earth pre-dating the Archean. It began with the formation of the Earth about 4.6billion years ago and ended, as defined by the ICS, 4billion years ago.[1] As of 2016, the ICS describes its status as "informal".[2] Geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth.[3][4] W. Brian Harland later coined an almost synonymous term, the "Priscoan period", from priscus, the Latin word for "ancient".[5] Other, older texts simply refer to the eon as the Pre-Archean.
passage: Helladic chronology
The Early Helladic I period (or EHI), also known as the "Eutresis culture", is characterized by the presence of unslipped and burnished or red slipped and burnished pottery at Korakou and other sites (metal objects, however, were extremely rare during this period). In terms of ceramics and settlement patterns, there is considerable continuity between the EHI period and the preceding Final Neolithic period (or FN); changes in settlement location during the EHI period are attributed to alterations in economic practices.