Hadean
The Hadean () is a geologic eon of the Earth pre-dating 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 ICS describes its status as ""informal"". 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", from "priscus", the Latin word for "ancient". Other, older texts simply refer to the eon as the Pre-Archean.
Swazian
The Swazian is a poorly defined geological stage in South Africa extending from about four billion years ago to 3 billion years ago , encompassing some of the Hadean and much of the Archean on the Geologic time scale. Other scales  assign the Swazian to parts of the Paleoarchean and Mesoarchean, 3.5 to 2.8 billion years ago. The Swazian is not recognized by the International Commission on Stratigraphy nor by the Geological Society of America, the two most widely accepted developers of international geologic time scales.