I
Very long span of geologic time; in formal usage, a portion of geologic time of the second-greatest magnitude (eons are longer).
Three eras are recognized: Mesozoic , and Cenozoic . Because of the difficulties involved in establishing accurate chronologies, the Precambrian , or earliest, eras are classified independently. An era is composed of one or more geologic periods .
II
[c mediumvioletred] (as used in expressions)
Cenozoic Era
Good Feelings Era of
Licchavi era
Malla era
Mesozoic Era
Paleozoic Era
Palaeozoic Era
{{link=Rana era">Rana era