Arkean

Arkean is an adjective and noun used primarily in geology to denote the earliest part of Earth’s history. In modern usage the term most often appears as a variant spelling of the Archaean (also Archean) Eon, the geologic interval roughly 4.0 to 2.5 billion years ago during which the planet’s crust formed and early continents began to assemble. Arkean is derived from Greek roots meaning ancient, and historically it has appeared in older scientific literature as an alternative transliteration of the same time period. Today, Archean and Archaean are standard spellings in most texts, while Arkean is considered archaic, regional, or variant.

Outside geology, Arkean may be used as a proper name in fiction, branding, or other contexts. Such uses are not standardized and do not imply any specific scientific meaning unless stated by the author or designer.

Because the term can refer to both a historical time frame and to other non-scientific uses, readers should check the context to determine whether Arkean refers to the geologic eon or to a proper noun. In scholarly writing, the preferred forms are Archean or Archaean; Arkean appears mainly as a historical spelling variant.