the.com/eon
a billion years pretending to be a single word, and absolutely winning the bluff
means An immense, indefinitely long stretch of time — and, in geology, a formal division of Earth's history larger than an era.
from From Greek 'aiōn,' meaning a lifetime, an age, or eternity — the same root that gives us 'eternal.' It traveled through Latin 'aeon' before settling into English, and in scientific use it was eventually drafted to mark the grandest slices of geological time. Older spellings still wear the 'a' (aeon), a small fossil of its classical past.
- geologic rank
- the largest chunk of geologic time, above eras
- current eon
- we live in the Phanerozoic, just 539 million years
- hidden majority
- Earth spent most of its life pre-Phanerozoic, lifeless or microbial
- loose usage
- casually means forever, scientifically means about a billion years
- greek roots
- from aion, meaning age or lifetime
phanerozoic eon — 541 million years ago to present, marked by visible animal life on earth
proterozoic eon — 2.5 billion to 541 million years ago, when complex cells and early animals emerged
archean eon — 4.0 to 2.5 billion years ago, earth's earliest eon with first life forms